Earth climates. Climate classifications: types, methods and principles of division, the purpose of zoning Climatic zones according to Alisov's classification

CLASSIFICATION OF CLIMATES ALISOV. Genetic classification of climates, which is based on the division earth's surface into climatic zones and regions in accordance with the conditions of the general circulation of the atmosphere, expressed in the predominance air masses of a certain geographical type - all year round or in one of the two main seasons. The boundaries between the zones are marked mainly by the position of the climatological fronts in winter and summer. There are 7 main climatic (circulation) zones: equatorial, two tropical, two temperate, arctic and antarctic. Each of them is characterized by a constant predominance of air masses of a geographical type, the same name with the zone. Then intermediate zones are distinguished: two zones of equatorial monsoons with winter predominance of tropical and summer equatorial air, two subtropical zones with winter predominance of polar and summer tropical air, subarctic with predominance of arctic air in winter and summer air temperate latitudes. In the tropical and subtropical zones, climate subtypes are distinguished: continental, oceanic, eastern periphery of oceanic anticyclones, western periphery of oceanic anticyclones; in the temperate zone - subtypes continental, oceanic, western coasts, east coasts(monsoon); in the subarctic and arctic zones- continental and oceanic subtypes.

CLASSIFICATION OF KÖPPEN CLIMATES. Classification of climates based on temperature and precipitation regimes. 5 types planned climatic zones, namely: A - humid tropical zone without winter; B - two dry zones, one in each hemisphere; C - two moderately warm zones without regular snow cover; D - two boreal climate zones on the continents with sharply defined boundaries in winter and summer; E - two polar regions of snow climate. The boundaries between the zones are drawn according to certain isotherms of the coldest and warmest months and according to the ratio of the average annual temperature and annual precipitation, taking into account the annual course of precipitation. Within zones of types A, C and D, climates are distinguished with dry winters (w), dry summers (s) and evenly humid (f). According to the ratio of precipitation and temperature, dry climates are divided into steppe climates (BS) and desert climates (BW), polar climates are divided into tundra climate (ET) and the climate of eternal (permanent) frost (EF).

Thus, 11 main types of climate are obtained: Af - rainforest climate, Aw - savannah climate, BS - steppe climate, BW - desert climate, Cw - warm temperate climate with dry winters, Cs - warm temperate climate with dry summers (Mediterranean) , Ci - moderately warm climate with uniform moisture, Dw - moderately cold climate with dry winters, Df - moderately cold climate with uniform moisture, ET - tundra climate, EF - eternal frost climate. For further detail, 23 additional features and corresponding indices (a, b, c, d, etc.) based on details in the temperature and precipitation regime. Many types of climates according to K. K. K. are known by names associated with the characteristic of this type vegetation.

Genetic classification of climates by B.P. Alisov

Principles of climate classification

To analyze the patterns of climate formation within the global system and solve practical tasks it is necessary to know the distribution of climatic values ​​over the globe or region, as well as the climatic complex as a whole.

Depending on the task of the study, there are different approaches to the classification of climates. If this is done for the purpose of analyzing the origin of the climate itself or for linking it with a complex of natural conditions (landscape-geographical zones), then such a division of climates is called a climate classification. , and if for applied purposes (servicing agriculture, construction, transport) - climatic zoning .

Classifications of climates and zoning are numerous and are determined by various tasks. There are classifications that link the distribution of vegetation, soils, river networks, and relief as a whole with climate, or study the patterns of formation of the global climate system from local climates.

Modern classifications and zoning are not limited to the division of climates, they also reveal their system, thereby drawing attention to their similarities.

The genetic classification of climates is based on the division of the earth's surface into climatic zones and regions in accordance with the conditions of the general circulation of the atmosphere, expressed in the predominance of air masses of a certain geographical type, during the year or in one of the two main seasons. In addition to the seasonality of circulation conditions, two varieties are distinguished in each zone: the climate of the lowlands and the climate of the highlands. This gives grounds for linking circulation boundaries with landscape ones.

In real conditions, the situation is more complicated. Circulation processes determine humidification at low latitudes, while thermal conditions differ little, and therefore the climate boundaries according to Alisov coincide well with landscape zones. In temperate latitudes, moisture is also determined atmospheric circulation. When determining climatic boundaries, the distance various parts mainland from the ocean.

Much the situation is more difficult with thermal boundaries in the warm half of the year, which in the extratropical zone strongly depends on radiation conditions.

The formal boundaries of the distribution of air masses under conditions of their continuous thermal transformation do not always correspond to landscape boundaries.

Latitudinal zones and types of climates according to Alisov, their features are given in the table. Latitudinal climatic zones represent four zones where one air mass predominates (EW, TV, SW, AB), and three zones where air masses of lower latitudes prevail in summer and higher latitudes in winter.

B.P. Alisov identifies seven main climatic (circulation) zones: equatorial, two tropical, two temperate, arctic and antarctic. Each zone is characterized by a constant predominance of air masses of the geographical type of the same name with the zone. Then intermediate zones are distinguished: two zones of equatorial monsoons with a winter predominance of tropical and summer equatorial air, two subtropical zones with a predominance of polar and summer tropical air, a subarctic zone with a predominance of arctic air in winter and summer air of temperate latitudes.

Scheme of latitudinal belts (zones) and climate types (according to B.P. Alisov)

From completely different considerations, although not without taking into account the average baric field, B.P. Alisov (1936–1952). This classification combines the rigor of a physical approach to formulating the principles of classification, the simplicity of the representations used, and the clarity of the results obtained.

Alisov took as a basis important circulation features that integrally characterize the temperature and humidity state of the climate of a certain region. He used the predominance of certain air masses in different seasons as a determining indicator, and the most frequent positions of the main atmospheric fronts(climatic fronts).

There are no quantitative characteristics for the position of these fronts, so they are carried out tentatively according to a synoptic experiment.

Let us give a brief overview of Alisov's climate system, presented in Table. 6.6.

In each hemisphere, four climatic zones are distinguished on the basis of the predominance of one of the main air masses in them during the year: equatorial, tropical, temperate, arctic (antarctic).

Three transitional zones are distinguished between the main belts, where, due to seasonal migration, air masses of lower latitudes prevail in summer, and higher latitudes in winter. This is a subequatorial belt, in which equatorial air prevails in summer, and tropical air in winter. In the subtropical zone, tropical air dominates in summer, and temperate in winter. In the subarctic (subantarctic) zone, the air is moderate in summer, and arctic (antarctic) in winter. In each of the latitudinal zones, continental and oceanic types of climate are distinguished. In addition, due to the fundamental differences in circulation processes at different boundaries of the continents, climate types are distinguished on the eastern and western coasts of the continents, including both part of the land and part of the adjacent sea area. In each zone, a mountain type of climate is distinguished.

Table 6.6.

Table 6.6. The system of belts and zones according to the classification of B.P. Alisova

Belts 1, 3, 6 do not appear on all meridians, the first two due to large shifts in circulation by season, the latter, on the contrary, due to the absence of a significant seasonal shift in air mass boundaries in some areas (Fig. 6.2).

Rice. 6.2. Climate classification scheme according to B.P. Alisov

According to the classification of B.P. Alisov, continental and oceanic types of climate are distinguished in the equatorial climate. They do not differ too much from each other in terms of temperature and humidity. Over the continent in the equatorial latitudes, the air is also very humid due to the large moistening of the underlying surface and the large evaporation of tropical vegetation. Therefore, no distinction is usually made between oceanic and continental equatorial climates. In latitudes close to the equator (up to 5–10° in each hemisphere), where the influx of solar radiation changes little during the year, a very uniform temperature regime is observed. Both at sea and on land long-term temperatures all months of the year from +24 to +28 °C. The annual temperature amplitude can be no more than 1 °C and usually does not exceed 5 °C. Daily temperature amplitudes are about 10–15 °С. Evaporation is high, and so is the absolute humidity. It may exceed 30 g/m 3 . The relative humidity is also great. Even in the driest months of the year it is above 70%.

Precipitation in the equatorial type of climate is plentiful, has a shower character and is often accompanied by thunderstorms. Most of them fall in the intertropical convergence zone: over the sea they are not as intense and not as frequent as over land. In general, 1000-3000 mm of precipitation falls per year. But in a number of places, for example, in the mountainous regions of Indonesia, in Central Africa, more than 6000 mm falls. In most areas, the distribution of precipitation throughout the year is more or less uniform; on land, these are areas of tropical rainforests in South America, Africa, and Indonesia. The landscape is a humid equatorial forest.

In some parts of the tropical oceans, in particular in the Indian and western Pacific oceans, as well as over South Asia and in the tropics of Africa and South America, the tropical monsoon regime dominates.

Along with a more or less sharp seasonal change in the prevailing air currents, there is also a change from tropical air to equatorial air from winter to summer. The air temperature in the tropical monsoon zone over the ocean is as high and has the same small annual amplitude as in the equatorial climate. Over land, the annual temperature amplitude is greater and increases with geographic latitude.

The most outstanding feature of this type of climate on the continents is the sharp difference between dry and rainy periods. During the winter, this type of climate is dominated by continental tropical air masses with high temperatures and no precipitation. In summer, with the advent of the summer southwest monsoon, carrying moist equatorial air masses, a rainy period begins, the temperature drops slightly. The amount of precipitation can vary greatly depending on the distance of the point from the ocean, on latitude, the duration of the rainy period, orographic conditions, the vertical power of the equatorial air mass, and other factors.

Thus, in the type of continental tropical monsoons, the year is sharply divided into dry (winter) and rainy (summer) periods. The annual course of temperature reveals a main temperature maximum in spring, a main minimum in winter, a secondary maximum in autumn, and a secondary minimum in summer during the summer monsoon. Due to the long dry period, the typical landscape in this type of climate is savannah, grading on the pole-facing peripheries into steppes and semi-deserts.

In this type, as well as in the continental one, there is a seasonal change of air masses. In the winter months, marine tropical air prevails here, the properties of which, naturally, differ greatly from continental air, and above all in temperature and humidity. At the same time, tropical marine air differs little from the equatorial air that comes with the summer monsoon. The type of oceanic monsoons is characterized by small annual (1−2 °С) and daily (not exceeding 2−3 °С) air temperature amplitudes. Average monthly temperatures are 24−28 °C. The most characteristic feature of the climate is the absence of a dry period in the strict sense of the word and the long duration of the summer rainy period. The winter monsoon is northeast, but since it carries moist marine tropical air, it also rains during the winter monsoon, but their amount is much less than during the summer southeast monsoon, which brings humid equatorial air mass.

It includes the Indian and West African monsoons. The summer monsoon is generally associated with the southwest air currents, the winter monsoon with the northeast. The annual course of precipitation is especially pronounced. In general, we can say that during the reign of the summer monsoon, 75% of the annual precipitation falls. The orography of the western coasts has a great influence on the magnitude and distribution of precipitation. Thus, on the high banks and on the slopes of the mountains facing the summer monsoon, precipitation increases sharply. In the annual course of temperature, the maximum occurs in spring.

The absolute and relative air humidity (maximum in summer) and cloudiness (sharp maximum in summer and sharp minimum in winter) also change sharply with seasons. For example, in Kolkata, the cloudiness is 84% ​​in July and 8% in January.

Due to dry winters, the tropical monsoon climate of the western coasts is especially characterized by a savanna landscape. One of the regions of the tropical monsoon zone experiences the highest average annual temperatures on the globe. On the southwestern shores of the Red Sea, Eritrea sometimes gets summer monsoon from the Southern Hemisphere. Its temperature is further increased as a result of the foehn process, so very high air temperatures are observed on the coast of Eritrea. At Massawa (15.6°N, 39.5°E) average temperature January and February +25÷+26 °C, July +35 °С, and average annual + 30 °С.

The most characteristic distinguishing feature of this type from the previous one is the long duration of the rainy period, often with a shift in the maximum precipitation to the end of summer and the beginning of autumn, and a relatively wet dry period. The air currents of the summer monsoon here are southwest, south and even southeast, while the winter monsoon is northeast. The northeastern currents of the winter monsoon, before entering the mainland, manage to travel a fairly long way over the water surface of the East China and South China Seas and the western Pacific Ocean, so the winter monsoon is quite humid here.

Thus, in Ho Chi Minh City (Vietnam, 10° 49" N, 106° 40" E), the summer monsoon begins in May (196 mm of liquid precipitation) and ends in November (122 mm), with the main maximum rainfall occurring for September (292 mm), and the secondary maximum for June (285 mm). Of the 1806 mm of rain falling in a year, almost 93% falls during the rainy season and 7% during the dry season. The maximum temperature falls in April (29 °C), during the rainy period the temperature drops from 28 °C in May to 26 °C in October and then does not change during the dry season.

The landscape is a humid equatorial forest.

Tropical climates are formed in areas dominated by tropical air masses. It is known that tropical air over the oceans is formed in subtropical anticyclones. Above the continents, the region of its formation are the deserts and savannas of the tropical belt. The tropical belt is characterized by high values ​​of the radiation balance: over the oceans they are about 5000 MJ/m 2 yr, and over the continents they are 2500 MJ/m 2 yr.

Over the continents in this belt, due to the extreme dryness, heat losses for evaporation are low. Therefore, despite the high values ​​of effective radiation and high albedo, the surface of the continents warms up strongly in summer and the continental tropical air acquires high temperatures.

This climate is observed in North and South Africa, in Arabia, in most of Australia, in Mexico, in the middle part of South America, that is, in those areas on both sides of the equator where there is no change of monsoons, where tropical air prevails all year round . These areas make up the belts of tropical deserts, which include the Sahara, the Arabian Desert, the deserts of Australia, etc.

Cloudiness and precipitation here are very small, the radiation balance of the earth's surface due to the dryness of the air and the large albedo of the earth's surface is less than in the equatorial belt. However, the air temperature is very high, since the heat consumption for evaporation is small. Summer is extremely hot, the average temperature of the warmest month is not lower than + 26 °С, and in some places almost up to + 40 °С. It is in the zone of tropical deserts that the highest temperature maxima on the globe are observed - about +57 ÷ + 58 °С. Winter is also warm, with the temperature of the coldest month between + 10...+ 22 °C.

The daily fluctuations in temperature are very large, sometimes reaching 40 °C.

Annual precipitation in most cases is less than 250 mm, and in some places less than 100 mm.

This type of climate is determined by the properties of marine tropical air, which is formed in those latitudes of subtropical anticyclones, to which the intratropical convergence zone in its seasonal displacement does not reach.

Along the equator-facing periphery of subtropical anticyclones, a stable regime of trade winds dominates here all year round with characteristic weather and climate conditions.

The oceanic tropical climate is characterized by moderately high temperatures, increasing towards the equator. The average temperatures of the summer months are from + 20 to + 27 °С. In winter, in the high-latitude parts of the trade wind zone, temperatures drop to + 10 ... + 15 ° С. The presence of an anticyclonic trade wind inversion at a low altitude prevents convection from developing upward. Cumulus and stratocumulus clouds occur in large numbers: the average cloud cover is about 50% or more. But there is no heavy precipitation in the trade winds, except for those islands where orographic conditions favor them. In the open ocean, the weather in the trade wind zone is predominantly dry, as the clouds do not reach the level of glaciation. Weak precipitation associated with the coagulation of droplets in clouds does not significantly change this situation. A characteristic feature of this type of climate is the development of tropical cyclones over the oceans, excluding the southern part of the Atlantic and the southeastern part of the Pacific oceans. In addition, significant precipitation is associated with them in this generally extremely dry climate.

It is also called the climate of the western coasts of the continents. On the western coasts of the continents, the winds of the trade winds of the northern quarter in the Northern Hemisphere and the southern quarter in the Southern Hemisphere prevail during the year. In the zone of trade winds, temperatures are relatively low, since air quickly enters here from high latitudes along the eastern periphery of subtropical anticyclones and, in addition, flows over the cold waters of cold ocean currents. The annual temperature amplitude is small, just like over the oceans. Precipitation is very low (less than 100 mm per year) due to low water temperatures and low-lying trade wind inversion, but humidity is high (80-90%) and fogs often occur. This is the climate of coastal deserts, such as the western coast of the Sahara, southern California, the Namib desert (South Africa) and Atacama (South America).

(The climate of the eastern coasts of the continents). This type of climate is very different from both the climate of the eastern periphery of oceanic anticyclones and the continental tropical climate. Throughout the year, on the eastern coasts, the removal of marine tropical air by the trade winds prevails. Trade winds on the western periphery of subtropical anticyclones, passing a long way over the oceans, are enriched with moisture and acquire components directed to the poles.

Due to the predominance of marine tropical air in all seasons of the year, a warm, humid climate with a large amount of precipitation forms on the eastern coasts. The climate of the eastern coasts of tropical latitudes is somewhat reminiscent of the equatorial climate, but differs from the latter in large annual air temperature amplitudes.

Coastal landscape - tropical forests.

In subtropical latitudes, i.e., at latitudes of the order of 25-40 °, climatic conditions are determined by a sharp seasonal change in circulation conditions and, consequently, a sharp change in the predominance of air masses. In summer, high pressure zones and polar fronts move to higher latitudes. At the same time, the subtropics are captured by tropical air from lower latitudes. Due to the shift of subtropical anticyclones to high latitudes, the pressure in the subtropics over the oceans is increased in summer. Above the land it is lowered. In winter, the polar fronts shift to low latitudes, and therefore the subtropics are captured by temperate air. At the same time, cyclonic activity spreads over the ocean to the subtropics. Over the continents, the pressure in the subtropics increases on average in winter, since winter continental anticyclones also spread to the subtropical latitudes of cold continents. Hence the seasonal differences in the weather regime, and, consequently, in the climate of the subtropics.

In summer, the subtropics inside the continents are under the influence of diffuse areas of low pressure, the so-called thermal depressions. They form masses of continental tropical air with high temperature, low moisture content and low relative humidity. The weather here in summer is cloudy, dry and hot. The average temperatures of the summer months are close to + 30 °С or exceed this value. In winter, cyclonic activity spreads to these areas, as cyclones often form here or polar fronts pass. The weather is unstable, with sudden changes in temperature and precipitation. Annual rainfall is not more than 500 mm, and sometimes much less. This is a zone of steppes, semi-deserts and deserts.

The zone of continental subtropical climate also includes a large (southern) part of the deserts of the Turan lowland, located on the territory Central Asia. Here, temperate air dominates in winter, so winter temperatures are much lower than in tropical deserts; in summer masses of continental tropical air are formed with very high temperature, low relative humidity, very little cloudiness and high dust content. Africa and Australia do not have this type of climate.

A special type of continental subtropical climate is the climate of high subtropical highlands. It is observed in the high uplands of Asia - Tibet and the Pamirs, at altitudes of 3500-4000 m. The climate is sharply continental, with relatively cool summers and cold winters. Precipitation is generally low; it is a high desert climate. However, the characteristic features of a continental subtropical climate - the predominance of moderate air masses in winter and tropical air masses in summer - persist here as well.

In the subtropical latitudes of the oceans, the anticyclone regime with cloudy and dry weather with weak winds prevails in summer, and cyclonic activity with rains and strong winds, often with storms. Annual temperature amplitudes are less than in the continental type, on average about 10 °C. In the eastern parts of the oceans, summer is relatively cool, since air currents from higher latitudes often penetrate here (along the eastern periphery of subtropical anticyclones) and cold ocean currents pass here. Summers are warmer in the western parts of the oceans. In winter, on the contrary, cold air masses from the continents (Asia, North America) and temperatures are lower than in the east. In the central parts of the oceans of the Northern Hemisphere, the average temperatures of the summer months in the subtropics are + 15 ... + 25 ° С, in the winter months + 5 ... + 15 ° С. In the Southern Hemisphere, winter temperatures are higher, summer temperatures are lower, and annual amplitudes are even smaller.

In summer, the western coasts of the continents in the subtropics are located on the eastern periphery of subtropical anticyclones or in their spurs. Clear and dry weather prevails. In winter, a polar front often passes or arises here with cyclonic activity and precipitation. Thus, the summer in the Mediterranean climate is quite hot and dry, the winter is rainy and mild. Snow may fall annually, but without the formation of a snow cover. Precipitation is generally not very high. A small amount of precipitation in summer gives the climate a character of some aridity. This type of climate is typical primarily for the Mediterranean region. Western Transcaucasia belongs to the subtropical type of climate. The Mediterranean type of climate is observed on the coasts of California, Oregon and Washington in North America, in the middle of Chile, in southern Australia, in the extreme south of Africa (Cape Peninsula).

The Mediterranean climate is characterized by a peculiar vegetation, including many drought-resistant species; these are forests and shrubs with a large admixture of evergreen species.

In winter, these areas are influenced by cold northwesterly air currents from the mainland; in summer, air from the ocean comes in southeast currents. The annual course of precipitation is opposite to the Mediterranean type. In winter, the weather is clear and dry; in summer, on the contrary, precipitation is abundant, falling in cyclones over the mainland, partly convective, partly frontal. The orographic increase in precipitation on the windward slopes also plays an important role. Precipitation is generally plentiful, and therefore the type of climate is characterized by richly developed forests of broad-leaved species. Snow falls, but the snow cover does not hold. For example, in Beijing (39.9°N, 116.5°E) the average temperature in July is +26°С, and in January -5°С; the annual amount of precipitation is 612 mm, of which 235 mm falls in July and 2 mm in December.

In the east of North America, in Washington (38.9°N, 77.0°W), the average temperature in July is +25°C, in January +1°C; precipitation is 1043 mm, of which 110 mm in July and 65 mm in November. This type of climate is observed in South America. Buenos Aires (34.6°S, 58.5°W) has an average temperature of +23°C in January and +10°C in July; annual rainfall is 1008 mm, of which 116 mm in March and 60 mm in July.

In temperate latitudes, large seasonal differences in radiation conditions are observed. In summer, the radiation balance of the underlying surface is high and in areas with little cloudiness it approaches the conditions of tropical latitudes, while on the continents it is negative in winter. The temperate latitudes are characterized by the most intense cyclonic activity on the polar and arctic fronts, so the weather regime here is very variable. In the Northern Hemisphere, there are great differences in the circulation conditions on the continents and oceans, which cause pronounced types of maritime and continental climates. In the predominantly oceanic Southern Hemisphere, the continental type of climate in temperate latitudes is practically absent.

Very significant differences in climate exist on the western and eastern margins of temperate continents. The climate of the western coasts, subject to the predominant influence of marine air masses, is transitional from maritime to continental; it is often referred to simply as the sea. On the eastern shores, a monsoon type of climate is observed, especially in Asia.

This type of climate is found on the continents of Eurasia and North America. It is characterized by warm summers and cold winters with stable snow cover. The annual temperature amplitude is large and increases with distance inland. Moisture conditions change in the direction both from south to north and from west to east.

In the southern part of the temperate latitudes of Eurasia, a high pressure regime prevails in winter. On climatological maps, it is in these latitudes that the center of the winter Asian anticyclone is located. Therefore, winter precipitation here is small and decreases with distance inland. For this reason, the snow cover is not high, and in Transbaikalia, near the center of the anticyclone, it reaches negligible values, despite the very severe winter. In summer, in the southern part of the temperate latitudes of Eurasia, anticyclones of a subtropical type are also not uncommon, contributing to hot and dry weather. Summer precipitation is greater, but they are also small due to high evaporation at high summer temperatures, so humidification in the southern part of temperate latitudes is insufficient. In general, 200–450 mm of precipitation falls here annually. As a result, starting from Moldova, through Ukraine, the southern part of the European territory of Russia and further beyond the Urals, up to Mongolia inclusive, steppes stretch, in which dry conditions are often created in summer.

In the higher latitudes of the temperate zone of Eurasia, the summers are less hot, but still very warm, the winters are more severe (for each given longitude), and the annual precipitation is large (300–600 mm). Continentality also increases from west to east (mainly due to a decrease in winter temperatures): annual temperature amplitudes increase and precipitation decreases. The snow cover here is higher and lasts longer. This is a zone of mixed or deciduous forests. In Moscow (55.8°N, 37.6°E), the average temperature in July is +18°С, in January –10°С; the annual amount of precipitation is 600 mm. In Novosibirsk (55.0°N, 82.9°E) +19°C in July and -19°C in January; precipitation for the year 425 mm. The maximum precipitation everywhere occurs in the summer.

Further north is the taiga zone, which stretches from Scandinavia to the Pacific Ocean, with the same patterns in climate change from west to east, but with more severe winters. Summers in the taiga zone are as hot as in lower latitudes, but winters are even colder. It is due to the severity of winter that the climate in the eastern part of the taiga zone reaches the greatest continentality. Precipitation is the same as in the zone of deciduous forests; sufficient moisture in general Western Siberia leading even to swamping. In Yakutsk (62.0°N, 129.6°E) +19°C in July and -44°C in January; rainfall for the year 190 mm. It is in Yakutia that the continentality of the climate reaches largest. On the mainland of North America, the same types of continental climate of temperate latitudes are found.

The Atlantic and Pacific oceans occupy large areas in the temperate latitudes of both hemispheres, and Indian Ocean− in temperate latitudes of the Southern Hemisphere. The prevailing westerly transport is better expressed over the oceans than over the continents, especially in the Southern Hemisphere. The wind speed is greater than over the continents. In the 40th and 50th latitudes of the Southern Hemisphere, between the zone of subtropical anticyclones and subantarctic latitudes, where the centers of deep cyclones most often pass, the average wind speeds are 10–15 m/s. The temperature distribution over the oceans is more zonal than over the continents at the same latitudes, and the differences between winter and summer are less pronounced. In connection with the cold summer, the tundra landscape is located on oceanic islands in such low latitudes, in which there is still no tundra on the continents. Thus, the Aleutian and Commander Islands, the Falkland Islands, and others are covered with tundra.

In the Northern Hemisphere, the western parts of the oceans are noticeably colder than the eastern ones in winter due to frequent intrusions of cold air masses from the continents. In summer, the difference is less. Cloudiness over the oceans of temperate latitudes is large and precipitation is significant, especially in subpolar latitudes, where the deepest cyclones are observed.

In the western parts of Eurasia and North America, in temperate latitudes, the transfer of marine air masses to the mainland both in winter and in summer sharply prevails. Therefore, the climate here bears a strong imprint of oceanic influences and is maritime. It is characterized by not very hot summers and mild winters without stable snow cover, sufficient rainfall and a more or less even seasonal distribution. That defines the landscape deciduous forests and meadows. Precipitation sharply increases on the western slopes of the mountains.

In North America, due to the presence of Cascade and rocky mountains this type of climate is limited to a relatively narrow coastal area. In Western Europe, it spreads inland with a gradual increase in continentality. For example, in Paris (48.8°N, 2.5°E) the average temperature in July is +18°С, and in January - +3°С; precipitation for the year 613 mm. In Europe, east of Berlin, the climate becomes continental. Within Russia, this type of climate passes into the continental climate of temperate latitudes, described above. Largest Quantities precipitation falls in this type of climate in Europe on the windward slopes of mountains. Above is a large amount of precipitation for Bergen, but at some stations in the Alps, more than 2500 mm falls per year.

In eastern Asia, the climate is typically monsoonal. Monsoons of temperate latitudes are a continuation of tropical and subtropical monsoons, they are very distinct and are observed approximately to the latitude of northern Sakhalin. Thus, a moderate monsoonal climate is observed in Primorsky Krai, in northeastern China, in northern Japan and on Sakhalin. In winter, the margin of the mainland is on the periphery of the Asian anticyclone and the transfer of cold air from Eastern Siberia, so the winter is cloudy and dry with significant cold weather and a sharp minimum of precipitation. In summer, cyclonic activity dominates over the east of Asia with fairly heavy precipitation. An example is the data for Khabarovsk (48.5°N, 135.0°E), where the average temperature in July is +21°С, in January –22°С and precipitation is 569 mm per year, of which (October - March) accounts for only 99 mm. In the northern regions of Russian Primorye, where the monsoon wind regime is weak or absent, winter is milder due to strong cyclonic activity and the distribution of precipitation throughout the year is uniform.

On the Atlantic coast of Canada and Newfoundland, the monsoon circulation is weak or absent. Winters are not as cold as in East Asia, and summers are quite warm

In the subarctic (subantarctic) belt, arctic (antarctic) air prevails in winter, and air of temperate latitudes prevails in summer. There are two main types of climate in the subarctic zone: continental and oceanic. Continental subarctic climate is observed mainly in the Northern Hemisphere, oceanic - in the Southern.

On the northern outskirts of Eurasia and North America, in latitudes that can already be called subpolar, there is a tundra zone. Winters are long and harsh, summers are cold and frosty. In Asia, in this type of climate, the cold poles of the Northern Hemisphere are located (the region of Verkhoyansk and Oymyakon). The average temperature of the warmest month is not higher than +10... +12 °С; this is the limit at which trees can grow. Cold summer determines the landscape of the tundra. Precipitation in the tundra is less than in the taiga zone - less than 300 mm, and in Eastern Siberia, where cyclones rarely fall into the tundra zone - even less than 100 mm. Although there is little precipitation, the cloud cover is high and there are many days with precipitation; therefore, they fall out in small quantities due to the low moisture content of the air at low temperatures. The maximum precipitation occurs in summer. No matter how small the precipitation, but at low temperatures they exceed evaporation, therefore, excessive moisture is observed in the tundra and waterlogging due to permafrost.

Over the oceans of the Southern Hemisphere south of 60°S. to the coast of Antarctica, the subpolar climate is characterized by a very uniform temperature distribution in summer - in most of the water area it is close to 0. But in winter, the temperature decreases rapidly and reaches -20 ° C and lower near the coast.

In these latitudes, the centers of cyclones most often pass, so the cloudiness here is very large; the frequency of precipitation and fog is also high. The prevailing western winds near the mainland are replaced by eastern ones.

The climate of the Arctic basin is primarily determined by the lack or complete absence of solar radiation in winter and a very large influx of radiation in summer. The annual radiation balance of the surface of the Arctic seas is generally positive; negative balance only on the Greenland plateau. Nevertheless, summer temperatures are not high, because the radiation is spent on the melting of snow and ice, and the temperature of the surface and air remains close to 0. The strong influence of the general circulation of the atmosphere is added to the influence of radiation conditions. In the Arctic Basin, intense cyclonic activity is observed in all seasons of the year. Cyclones originate on Arctic fronts and also penetrate into the Arctic from lower latitudes, where they develop on polar fronts. Increased pressure prevails throughout the year over the high plateau of Greenland. But in the rest of the Arctic, the division changes significantly from month to month, and anticyclonic systems are found on average maps over relatively small areas in different parts ocean, and in winter over Alaska and over northeast Asia. Cloud cover in the Arctic Basin is generally high and winds are stronger. Average monthly temperatures in the Arctic Basin range from -40°C in winter to 0°C in summer.

There are several areas:

The warmest Atlantic-European region of the Arctic, where in the process of cyclonic activity, deep removals of warm Atlantic air to high latitudes occur, especially raising temperatures in winter.

In the Asian (East Siberian), Canadian and Pacific regions of the Arctic, winters are much colder than in the Atlantic-European region, but summers are generally the same. At Cape Shalaurova (73.0° N, 143.3 E) +3°C in July, −31°C in February, mean annual −15°C; rainfall per year 140 mm.

In the center of the Arctic Basin, average temperatures range from -40 °C in winter to 0 °C in summer.

Greenland, with its high altitude and prevailing anticyclonic regime, has a particularly harsh continental climate. On the plateau, at the Eismitte station (70.9° N, 40.6° W, 3300 m), the average temperature in July is –14°С, in January –49°С, and the annual temperature is –32°С.

The climate of the icy continent is the most severe on the globe. Average annual temperatures decrease here from -10 °С on the coast, at the latitude of the Arctic Circle, to -50... -60 °С in the central regions of the mainland. The average annual rainfall for the entire mainland is about 120 mm; from the coast into the mainland, precipitation greatly decreases.

The main role in the severity and dryness of the climate of Antarctica is played by the snowy surface of the mainland, its high altitude above sea level (about 3000 m on average, and up to 3500 m or more in the center of East Antarctica) and the prevailing anticyclonic circulation regime. Despite the very large summer influx of solar radiation, the high albedo of the snow surface and effective radiation lead to the fact that the annual radiation balance is negative on the entire continent. The negative radiation balance is replenished by the influx of heat from the atmosphere. Cyclonic activity in the Southern Hemisphere develops intensively over the ocean around Antarctica. But on the mainland Antarctica, cyclones penetrate mainly in the western part of the mainland. Cyclones rarely penetrate East Antarctica. Thus, the high-pressure regime turns out to be unquestionably predominant here. The coast of Antarctica is a zone with a moderately humid and relatively mild climate. In summer, the maximum temperatures here sometimes rise above zero and the snow melts intensively. Strong katabatic winds from the high plateau of the mainland are especially characteristic of very many areas of the coast. Together with cyclones passing near the mainland, katabatic winds lead to the fact that even average wind speeds in a number of places on the coast reach 15–20 m/s. Precipitation on the coast of East Antarctica is 400-500 mm, West - 600-700 mm.

On the glacial slope, in a zone 600–800 km wide (in East Antarctica), strong katabatic winds are also observed, which create a snowstorm transport of snow. Average monthly wind speeds here are 8−13 m/s. The cloudiness is small, but nevertheless, this zone is often influenced by cyclones passing through the ocean or penetrating deep into the mainland. Therefore, snowfalls and blizzards are more frequent here than inside the mainland, and in the lower part of the slope even more often than on the coast.

At Pionerskaya station (69.7° S, 95.5° E, 2700 m), the mean temperature in August is −48°С, in December and January, −23°С, the mean annual temperature is −38°С; annual rainfall 848 mm

On the high inner plateau of East Antarctica, with its predominantly anticyclonic regime, the average wind speeds decrease to 3–4 m/s. Here, powerful surface inversions are constantly preserved above the snowy surface, and exceptionally low surface temperatures are observed in winter, almost down to -90 °C. The average temperatures of the winter months are about -70 °C, and the summer months are about -30 °C. Even in summer, maximum temperatures are below -20°C. Clear weather prevails; precipitation is very small, about 30-50 mm per year. One third to one half of the precipitation is created by hoarfrost deposits from ice clouds on the snow cover. The moisture content in the interior of the Antractida is very low.

Under the same latitudes, East Antarctica is much colder than West Antarctica; in inland regions by almost 30 °C. This is explained not only by the heights of the terrain, but also by the fact that West Antarctica is relatively often visited by cyclones that draw warm sea air onto the mainland.

The climate of the East Antarctica plateau is characterized by Vostok station (72.1° S, 96.6° E, 3420 m), where the average temperature in August is –68 °С, in December –33 °С, the average annual temperature is –55 °С, absolute minimum -88 °С. Precipitation per year is about 40 mm.

At the very South Pole, closer to the ocean and more prone to cyclonic activity (Amundsen-Scott station, 2880 m), the climate is somewhat milder: average temperatures in August and September are -59 °С, in January -28 °С, and -49 in a year. °C. The annual amount of precipitation is 55 mm.

Classification of climates BP Alisova Born on August 5, 1891 in Maloarkhangelsk, Oryol province, in a family of employees. He studied at the Kursk gymnasium. In 1911 he entered the Faculty of Physics and Mathematics of Moscow University. In 1915 he went to the front and participated in the First World War, and then from 1917 to 1921, during civil war, served in the Red Army. Since 1921 he returned to scientific activity, took up meteorology. Scientific activity began with the study climatic conditions resorts of the North Caucasus by organizing a reference actinometric station in Kislovodsk. In 1931 he moved to Moscow and until 1941 worked at the State Geophysical Institute. In 1933 began hydrometeorological climatology. In November 1941, he moved to Moscow University as a professor in the Department of General Physical Geography of the Faculty of Geography. In 1944–1958, he was the head of the Department of Meteorology and Climatology at Moscow State University. pedagogical activity at the Moscow Institute, where he laid the foundations of teaching

B. P. Alisov proposed to allocate climatic zones and regions based on the conditions of the GENERAL CIRCULATION OF THE ATMOSPHERE. Seven main climatic zones: equatorial, 2 tropical, 2 temperate and 2 polar. It is distinguished as zones in which climate formation occurs all year round under the predominant influence of air masses of only one type. Between them there are 6 transitional zones, characterized by a seasonal change in the prevailing air masses: 2 subequatorial, 2 subtropical, subarctic and subantarctic zones. The boundaries of the zones are determined by the average position of the climatological fronts. In each of the latitudinal zones, there are 4 main types of climate: continental, oceanic, the climate of the western coasts and the climate of the eastern coasts.

equatorial climate. In the equatorial climate, continental and oceanic types of climate are distinguished, which do not differ too much from each other in terms of temperature and humidity. There is a very uniform temperature regime. Precipitation is heavy, showery in nature and often accompanied by thunderstorms. 1000 - 3000 mm of precipitation falls per year. The annual course of precipitation is explained by the monsoonal nature of the atmospheric circulation.

Rhino Vegetation equatorial climate represents: creepers, up to hundreds of meters long; orchids, ferns, cacti; water hyacinth is able to form real floating islands. Animals: numerous insects, frogs, small snakes; parrots; crocodiles and hippos; caimans and tapirs; rhinoceros, anaconda and many others.

Subequatorial climate. Here there is a change of winter and summer monsoons, that is, in winter, eastern transfer dominates, changing in summer to western. Along with a sharp seasonal change in the prevailing air currents, there is also a change from tropical air to equatorial air from winter to summer. The air temperature in the tropical monsoon zone over the ocean is as high and has the same small annual amplitude as in the equatorial climate. In the subequatorial zone, B.P. Alisov identifies 4 types of tropical monsoon climate: 1) continental monsoons 2) oceanic monsoons 3) monsoons of the western coasts 4) monsoons of the eastern coasts

Elephants It is in the subequatorial climate that endemic species such as the African baobab and the Australian bottle tree grow, as well as a variety of acacias, fan palms and many more species. Of the animals of the herd of ungulates: antelopes, zebras, giraffes; elephants, hyenas; termites and worms.

Tropical climates. They form in areas dominated by tropical air masses. Tropical air over the oceans is formed in subtropical anticyclones. There is a large albedo and large values ​​of effective radiation. Despite this, the surface of the continents is very warm, and the continental tropical air acquires high temperatures. The following types of tropical climate are distinguished: 1) continental tropical climate 2) oceanic tropical climate 3) climate of the eastern periphery of oceanic anticyclones 4) climate of the western periphery of oceanic anticyclones

Lions Flora of the tropics - eucalyptus trees - very tall trees with sparse crowns; date palm; aloe, havortia and gasteria store water in the leaves; lithops consist of 2 fused leaves; cacti. Animals: eucalyptus koala bear; wildebeest, lion, buffalo, leopard, parrots, rhinoceros, hippopotamus, giraffe, elephant, green turtle.

subtropical climates. In subtropical latitudes, climatic conditions are determined by a sharp seasonal change in circulation conditions and a sharp change in air masses. Due to the shift of subtropical anticyclones to high latitudes, the pressure in the subtropics over the oceans is increased in summer. Over land pressure is reduced. In connection with the summer warming of the land, areas appear above it low pressure called thermal depressions. There are 4 main variants of the subtropical climate: 1) subtropical continental 2) oceanic subtropical 3) subtropical western coasts or Mediterranean 4) subtropical eastern coasts or monsoon

Panda Trees of the subtropics: evergreen - juniper, strawberry tree; coniferous - cedar, cypress; as well as chestnut, hornbeam, oleander, bamboo, orange, ginkgo, sequoia, wild olive and others. Fauna: bamboo bear - panda; ungulates - doe, mountain sheep; birds - sparrows, wheatears; chameleons, lizards, turtles.

temperate climates. In temperate latitudes, large seasonal differences in radiation conditions are observed. In summer, the radiation balance of the underlying surface is high and, in areas with little cloudiness, approaches the conditions of tropical latitudes. In winter on the continents it is negative. Temperate latitudes are the scene of the most intense cyclonic activity on the polar and arctic fronts, so the weather regime here is very variable. In the temperate zone, 4 types of climate are distinguished: 1) continental 2) maritime climate of the western parts of the continents 3) monsoon climate of the eastern parts of the continents 4) oceanic

Fox Plants temperate climate numerous and varied - these are annuals such as snowdrops; bulbous: tulips, crocuses; coniferous trees: cedar, fir, larch; creepers: lemongrass, grapes; as well as maple, oak, walnut. Animal species: hare, fox, wild boar, birds: jay, black grouse, crow, woodpecker; elk, rodents and others.

Subantarctic and subarctic climates. In these belts, arctic (antarctic) air prevails in winter, and air of temperate latitudes prevails in summer. There are 2 main types of climate here: continental and oceanic. Winters in these zones are long and severe, summers are cold and frosty. Although there is little precipitation, the cloud cover is high and there are many days with precipitation; consequently, they fall out in insignificant quantities due to the low moisture content of the air at low temperatures. The maximum precipitation occurs in summer. Precipitation exceeds evaporation, therefore, excessive moisture is observed in the tundra and waterlogging due to permafrost.

Brown bear The vegetation of the subarctic climate is mainly represented by coniferous trees: spruce, pine, fir, larch, cedar; birch occurs. Animals: elk, brown bear, squirrels, muskrat; birds - capercaillie, partridge, ducks; lizards. The fauna is represented by hairy bison, penguins, sea ​​lions, albatrosses.

The Arctic climate is determined by the lack or complete absence of solar radiation in winter and its very large influx in summer. Summer temperatures are not high because radiation is spent on melting snow and ice, while surface and air temperatures remain close to zero. The influence of radiation conditions is accompanied by a strong effect of the general circulation of the atmosphere. In all seasons of the year, intense cyclonic activity is observed here. Cyclones originate on arctic fronts and also penetrate from lower latitudes where they develop on polar fronts. The arctic climate is characterized by high clouds and strong winds.

Polar bear The vegetation of the Arctic climate is sparse: mosses and lichens, where the climate is milder, saxifrage grows. The animals here are those that tolerate cold well - these are walruses and seals, polar bears and arctic foxes, "bird markets" are numerous here, the musk musk ox lives - an ungulate adapted to the meager Arctic food.

Antarctic climate. The climate of the icy continent is the most severe on the globe. The average annual temperatures are very low, the average annual rainfall for the entire continent is -120 mm. The main role in the severity and dryness of the climate of Antarctica is played by the snowy surface of the mainland, its high altitude above sea level, and the prevailing anticyclonic circulation regime. Despite the very large summer influx of solar radiation, the high albedo of the snow surface and effective radiation lead to the fact that the annual radiation balance is negative on the entire continent. It is replenished by the influx of heat from the atmosphere. Cyclonic activity is intensively unfolding over the ocean around Antarctica. Cyclones penetrate the mainland mainly in the western part, where the coastline is quite indented and there are bays that protrude far into the mainland. Cyclones rarely penetrate East Antarctica.

There are no higher plants. Flora is represented by mosses, colorful lichens, microscopic algae. Animals: summer inhabitants - skua, Belek - baby seal petrel, penguins, seals. In winter, only emperor penguins remain in the bitter cold.

The climate is one of the physical and geographical characteristics of the area, and thus it is determined primarily geographic location the latter, that is, the latitude, the distribution of land and sea, the nature of the land.

In shaping the climate of any area, its height above sea level plays an important role, and the climate sea ​​coasts and island countries - currents in the ocean.

There are several classifications of climates. There are strictly scientific, detailed classifications of the climates of the entire globe, there are classifications for certain geographical regions and even for individual countries.

The most simple and well-known classification, which is used by most people, although it is not officially recognized and is not complete, is the following. There are cold, temperate and hot climates - according to the temperature regime, in addition, each of the three main types of climate can be additionally characterized, depending on the precipitation and humidity regime, as marine (humid, with a smooth temperature variation) or continental (dry, with sharp temperature fluctuations). ).

This is a simplified, approximate classification of terrestrial climates that does not include many important climatic features such as the monsoon zone or the highlands, etc.

There are a number of classifications created by famous climatologists: W. Koeppen, B.P. Alisov, A.A. Grigoriev, M.I. Budyko, L.S. Berg and others.

An interesting and at the same time simple classification of the climatic regimes of the northern hemisphere was proposed by the scientist M.I. Budyko. This classification takes into account, in addition to temperature and humidity regimes, also the radiation balance. It provides for only five climatic regimes:

arctic, with the presence of snow cover, negative air temperatures and negative or close to zero radiation balance;

tundra, with average monthly temperatures ranging from 0 to 10 gr. with a positive radiation balance;

forest zones , with average monthly temperatures over 10 gr. with a positive radiation balance and sufficient moisture, when evaporation is at least half of the evaporability (maximum possible evaporation);

arid zones(steppes and dry savannas), where, with a positive radiation balance, evaporation is from one tenth to one half of the evaporation value;

deserts, where, with a positive radiation balance, evaporation is less than one tenth of evaporation.

In different geographical areas, there can be several climatic regimes during the year, for example, in winter - arctic, in summer - arid zones.

63 Question. Climate classification globe V.P. Koeppen.

Answer:

The Köppen climate classification is one of the most widely used classification systems for climate types.

The classification was developed by the Russian and German climatologist Vladimir Petrovich Köppen in 1900 (with some further self-made changes in 1918 and 1936). It is based on the concept that the best criterion for climate type is what plants naturally grow in a given area.

Classification of climates based on temperature and precipitation regimes. There are 5 types of climatic zones, namely: A - humid tropical zone without winter; B - two dry zones, one in each hemisphere; C - two moderately warm zones without regular snow cover; D - two boreal climate zones on the continents with sharply defined boundaries in winter and summer; Ε - two polar regions of snow climate. The boundaries between the zones are drawn according to certain isotherms of the coldest and warmest months and according to the ratio of the average annual temperature and annual precipitation, taking into account the annual course of precipitation. Within zones of types A, C and D, climates are distinguished with dry winters (w), dry summers (s) and evenly humid (f). According to the ratio of precipitation and temperature, dry climates are divided into steppe climates (BS) and desert climates (BW), polar climates are divided into tundra climate (ET) and the climate of eternal (permanent) frost (EF).

Thus, 11 main types of climate are obtained (see below). For further refinement, 23 additional features and corresponding indices (a, b, c, d, etc.) are introduced based on details in the temperature and precipitation regime. Many types of climates according to the Köppen climate classification are known by names associated with the vegetation characteristic of this type.

Letter designations for the Köppen climate classification:

(names may be repeated, as the Köppen scheme is not the same as the belt scheme)

A - tropical and equatorial

B - dry, subequatorial, tropical

C - temperate, subtropical and continental

D - continental, subarctic (boreal)

E - polar, subarctic, arctic

Af - rainforest climate

Aw - savannah climate

BS - steppe climate

BW - desert climate

Cs - climate is warm temperate with dry summers (Mediterranean)

Cw - warm temperate climate with dry winters

Cf - climate is moderately warm with uniform humidification

Ds - climate is moderately cold with dry summers

Dw - climate is moderately cold with dry winters

Df - moderately cold climate with uniform moisture

ET - tundra climate

EF - permanent frost climate

Additional letters: third for the hottest, fourth for the coldest month of the year

i - extreme heat: 35 °C and above

h - very hot: 28 - 35 °C

a - hot: 23 - 28 °C

b - heat: 18 - 23 °C

l - medium: 10 - 18 °C

k - cool: 0 - 10 °C

o - cold: -10 - 0 °C

c - very cold: -25 - -10 °C

d - excruciatingly cold: -40 - -25 °C

e - permafrost: −40 °C and below

For example:

BWhl (Aswan, Egypt) - desert climate with temperatures in July 28-35 °C, and in January: 10-18 °C

Dfbo (Moscow, Russia) - moderately cold (continental) with a July temperature of 18-23 °C, and January: −10-0 °C

Cshk (Antalya, Turkey) - Mediterranean climate with temperatures in July 28-35 °C, and in January: 0-10 °C

64 Question. Differences in climate classification according to L.S. Berg and B.P. Alisov.

Suggested answer:

Outstanding Soviet scientist L. S. Berg developed the following classification of the Earth's climates. He identified two large groups:

1. Lowland climates

2. Climates of highlands.

Among the climates of the lowlands, L. S. Berg distinguishes eleven types:

1. Climate tundra-in the arctic and Antarctica.

2. The climate of the taiga

3. Climate of temperate forests

4. The climate is monsoonal - in the Amur, in Manchuria (Northeast China), Northern China, South Sakhalin and Northern Japan.

5. Climate of the steppes

6. Desert climate with cold winters

7. The climate of the Mediterranean countries - on the southern coast of Crimea, southern Australia, California. Here summers are hot, and winters, although warm, are rainy.

8. The climate of subtropical forests - in Southern China, Southern Japan, Northern India, Transcaucasia, South Africa, Southeast USA and the La Plata region in South America.

9. Desert climate with warm winters - in the Sahara, the deserts of Arabia and Australia, the Atacama Desert in Chile.

10. The climate of the tropical forest-steppe (savannah area) - in Venezuela, Guiana, south of the Amazon, in tropical America, in northern Australia, on the Hawaiian Islands.

The climate of tropical rainforests is in the Amazon basin, in the eastern part of Central America, in the Greater Antilles, in southern Florida, in tropical Africa, in New Guinea and in the Philippine Islands.

The climates of the uplands, as we have already mentioned, repeat the main types of climates of the lowlands. In addition, on the hills there is a climate of eternal frost.

B. P. Alisov proposed to allocate climatic zones and regions based on the conditions of the general circulation of the atmosphere. Seven main climatic zones: equatorial, two tropical, two temperate and two polar (one in each hemisphere) - he distinguishes as such zones in which climate formation occurs all year round under the predominant influence of air masses of only one type: equatorial, tropical, temperate ( polar) and arctic (in the southern hemisphere of the Antarctic) air.

Between them, Alisov distinguishes six transitional zones, three in each hemisphere, characterized by a seasonal change in the prevailing air masses. These are two subequatorial zones, or tropical monsoon zones, in which equatorial air prevails in summer and tropical air in winter; two subtropical zones in which tropical air dominates in summer and temperate in winter; subarctic and subantarctic, in which temperate air prevails in summer, and arctic or antarctic air in winter. The boundaries of the zones are determined by the average position of the climatological fronts. Thus, the tropical zone is located between the summer position of tropical fronts and the winter position of polar fronts. Therefore, it will be occupied mainly by tropical air all year round. The subtropical zone is located between the winter and summer positions of the polar fronts; therefore, it will be under the predominant influence of polar air in winter, and tropical air in summer. The boundaries of other zones are defined similarly.

65 Question. Classification of climates B.P. Alisova (equatorial, subequatorial).

Answer:

equatorial belt . Continental and oceanic types of equatorial climate. These types of climate are very similar due to the dominance of homogeneous equatorial air. Temperatures in the entire belt are high throughout the year (+24 ... + 28 ° С), air humidity is high. There is a lot of precipitation - about 2000 mm. A significant amount of precipitation is due not only to the high absolute and relative humidity of the air, but also to its moisture-unstable stratification. The vertical instability is facilitated by the fact that the wet adiabatic gradients in it are smaller than the vertical temperature gradients. Seasonal fluctuations in average monthly temperatures on land (3-4°) and precipitation are insignificant. Two small maximums in temperature and precipitation (they are the result of thermal convection) occur after the days of the equinoxes, a slight decrease in temperatures and a decrease in precipitation occur after the days of the solstices. Daily temperature fluctuations on land reach 10-15°C. This is a zone of low pressure, ascending air currents, weak winds. In a narrow equatorial strip, weak westerly winds prevail. Over the land, which warms up quickly, convection develops during the day, powerful cumulonimbus clouds form, in the afternoon there are heavy rains, usually accompanied by thunderstorms (the so-called zenithal rains). Over the sea showers and thunderstorms occur at night. This is the main difference between the oceanic climate and the continental climate, in addition, it has a very small daily and annual temperature amplitude (2-3 ° C); excessive moisture. In the conditions of the equatorial climate, moist evergreen forests grow on land.

subequatorial belts. They are characterized by a seasonal change of air masses: the summer monsoon brings EV, the winter monsoon (trade wind) brings TV.

Continental monsoon climate. On land in summer it is hot (26-27°C) and humid, like at the equator, about 1500 mm of precipitation falls, the amount of which decreases as you move away from the equator to 250-300 mm. In the same direction, the duration of the dry winter season increases from 2-3 months to six months. In winter, the temperature is about + 18 ... + 20 ° С, the humidity of the kTV is low, there is no precipitation. In spring, the air temperature rises rapidly and reaches a maximum of 30°C or more at the end of the dry season, for example, in India - in May up to 34-35°C. This is due to a complex of reasons: close to the zenithal position of the Sun and a cloudless sky, which causes an abundance of solar radiation, as well as insignificant heat consumption for evaporation, since after a dry winter the water reserves in the soil are small. Therefore, excess heat is spent on heating the air. As a result, three thermal seasons are distinguished here: a very hot spring, a hot summer-autumn period, and warm winter. Such a climate with wet summers and dry winters is called monsoonal. Humidity is close to normal and slightly less than one. Variable-moist sparse deciduous forests and savannas grow (from tall grasses to xerophytic shrubs and deserts).

The climates of the coasts of the continents in the subequatorial zones differ little from the mainland monsoon.

On the western coasts of the continents, due to the coastal position and cold currents, the temperature in all seasons is 2-3 ° C lower than inside the continents. The amount and mode of precipitation are the same.

The climate of the eastern coasts of the continents differs from the mainland one in that in winter the MTV (trade wind) flows from the ocean from tropical high-pressure belts, but it is stably stratified. Therefore, there is almost no precipitation on the low coasts, and only on the mountainous shores on the slopes of the eastern exposure, insignificant precipitation falls, the amount of which decreases with the height of the mountains. An example is the climate of the east coast of Brazil. Moisture conditions and natural vegetation zones are generally similar to inland areas.

The oceanic climate is characterized by more even temperatures (25-22 °C), humid summers and dry winters. The annual rainfall is about 1500 mm. Here, often at the end of summer - beginning of autumn, tropical cyclones with hurricane-force winds and showers occur.

66 Question. Classification of climates B.P. Alisova (tropical).

Answer:

Tropical belts. Mainland tropical climate. It is developed on most of the continents. KTV dominates there all year round. The temperature in summer is +30 ... + 35°С, in winter about + 20°С. The daily amplitude of air temperature is 30-40°C, and on the sandy surface it reaches 80°C. The annual amplitude of air temperature is 10-15°C, which is less than the daily one. There are almost no rainfall. The lack of precipitation in winter is associated with subsidence, adiabatic heating and drying of air in the high pressure zone. There is no precipitation in summer due to the low relative humidity of the air and the high position of the condensation level. Only near the borders with subtropical belts in winter is cyclonic activity poorly developed and 100-200 mm of precipitation falls. At the borders with subequatorial belts the same amount of precipitation falls in summer due to the sometimes penetrating here the summer equatorial monsoon. Humidification is negligible. Such a climate is called arid and even extra-arid. The greatest tropical deserts of the world are located here: the Sahara, the deserts of Arabia (Rub al-Khali, Greater and Lesser Nefud), Australia (Great Sandy, big desert Victoria, Simpson), the Kalahari semi-desert (in Africa).

The climate is peculiar on the western coasts of the continents, where MTV prevails throughout the year. It moves along the eastern peripheries of subtropical oceanic highs from colder temperate latitudes towards the equator above cold currents. In this regard, temperatures are usually low - about +20°C in summer and +15°C in winter. When moving to low latitudes, the air warms up and moves away from saturation. The formation of clouds is also not facilitated by oceanic baric maxima with an inversion layer at a low altitude due to the effect of latitude - about 1000 m. upper layers. The inversion prevents the development of convection. However, the MTV, brought by the strong daytime breeze on the coast, contains a lot of water vapor. This raises the relative humidity of the air here to 83-85% and leads to the formation of dew and fog on the coast at night. Moisture is negligible, so coastal deserts stretch here. To designate the climate of coastal deserts, washed by cold currents, the term "garua climate" is used (Spanish garua - dense drizzling fog).

On the eastern coasts of the continents, along which warm currents flow and over which the air receives a lot of moisture, the climate is different: high temperatures - +25 ... + 28 ° C in summer, about + 20 ° C in winter, quite a lot of precipitation - up to 1000 mm, especially in summer. Humidification is excessive. In the humid climate of the tropical zone, evergreen tropical forests grow.

The oceanic climate of the tropical belt is formed in areas of high pressure with an inversion layer and stable winds. There is a spatial heterogeneity of climatic conditions, which manifests itself in the regime of all elements. In the east of the oceans above the cold currents, the air temperature is + 20 ... + 15 ° С, there is little precipitation; in the west of the oceans, due to warm currents, temperatures rise to +25 ... + 20 ° С, precipitation becomes 500–1000 mm. Tropical hurricanes are typical.

The listed climatic zones lie mainly within the boundaries of the hot thermal zone, limited by annual isotherms of +20°C (winter temperatures of +15°C). In these belts, temperature differences are very small, so the main signs of seasonal changes in nature are the amount and regime of precipitation. The development of vegetation here is limited not by temperature, but by precipitation, and not just by their annual amount, but by the duration of dry and wet periods. The strike of natural vegetation zones is different: sometimes latitudinal, sometimes meridional, it is also subject to the laws of moistening conditions.

67 Question. Classification of climates B.P. Alisova (subtropical).

Answer:

subtropical belts. The climate is formed under the influence of the seasonal change of air masses: TV - in summer, which is formed in the belt itself under the influence of high insolation, and HC - in winter, coming from temperate latitudes.

The continental subtropical climate is arid, with hot (about +30°С) dry summers and cool (0...+5°С), relatively humid (200-250 mm) winters, with unstable frontal weather. Humidification is insufficient, therefore natural zones of deserts, semi-deserts, and dry steppes predominate. In Eurasia, this climate is developed in the center of the continent, far from the oceans, especially in the basins. In North America, it formed in the Colorado Plateau and the southern Great Basin Highlands as a result of their orographic isolation from maritime influence.

The climate of the western coasts of the continents is called Mediterranean, as it is most typical for the Mediterranean coast (Southern Europe, Western Asia, North Africa), although there are areas with such a climate on other continents. It is characterized by relatively hot (over +20°C) dry summers with anticyclone weather, mild (about +10°C) wet (500-700 mm) winters with frontal precipitation and unstable weather. Vegetation - dry-loving evergreen hard-leaved forests and shrubs. Currently, vineyards, plantations of citrus fruits and other subtropical crops predominate.

The climate of the eastern coasts of the continents is monsoonal; it is best expressed in Eurasia. In summer, a stable monsoon from the ocean (MTW) ​​prevails, it is hot (+25°С), humid. In late summer - early autumn, typhoons from the sea are frequent with gusty winds and heavy rainfall. Winter is relatively cool (on average 0...+5°С, but in some places below 0°С) and relatively dry, since the monsoon from the land from seasonal baric maxima, in particular from the Asian one, brings SH. But near the coasts and on the islands, frontal precipitation also occurs in winter. The total amount of precipitation is about 1000 mm. Humidification is sufficient. Vegetation - variable-moist deciduous broad-leaved and mixed forests. High degree of agricultural development.

The oceanic climate is reminiscent of the Mediterranean climate in terms of precipitation - relatively dry summers, wet winters with frontal precipitation. The temperature in summer is about 20°С, in winter 15°С.

The subtropical belt as a whole is characterized by predominantly positive (according to long-term data) temperatures throughout the year. However, in winter, short-term temperature drops to negative values and even snowfall, especially in monsoonal climates. On the plains, it melts quickly, in the mountains it can persist for up to several months. The exception is the largest and highest (4-5 km) highlands of the world, Tibet, located in this belt. It is characterized by a special kind of sharply continental climate: cool summers, severe winters, and little rainfall. Alpine deserts are developed on the highlands.

68 Question. Classification of climates B.P. Alisova (moderate).

Answer:

temperate zones. In these belts, the HC dominates during the year, but intrusions of both TV (especially in summer) and AW (in summer and winter) are possible. In these belts, the radiation balance is peculiar: in summer it is positive due to the rather high altitude of the Sun and the significant length of the day, in winter it is negative due to the low altitude of the Sun, short daylight hours, large reflectivity of the snow. Feature belts - intense cyclonic activity on the fronts both between the TS and HC, HC and AW, and between MW and SHW. It is associated with unstable weather conditions, especially in winter.

The mainland climate is moderately continental and sharply continental; expressed only in the northern hemisphere - in Eurasia and North America. KUV dominates, MUV invasions are not uncommon from the west. The average temperature of the warmest summer month July changes from +12°C in the north to +25... +28°C in the south, the coldest - January - from -5°C in the west to -25...-30°C in the center of the continents, and in Yakutia is even below -40°C. Low winter soil and air temperatures and a small amount of snow in Eastern Siberia support the existence of permafrost. Annual precipitation decreases from west to east from 700-600 mm to 300 mm and even to 200-100 mm in the Middle and Central Asia. In North America, precipitation decreases from east to west. More precipitation falls in summer than in winter, and this difference is more significant in the center of the continents, especially in Eastern Siberia, due to a very dry anticyclonic winter. Precipitation of frontal origin predominates: in summer they fall from the local MW, in winter from the incoming warmer MW. In summer, convective precipitation also falls, and in front of the mountains (for example, in front of the Tien Shan, Altai) - orographic precipitation. Due to the great length of the belt from north to south, it often distinguishes the northern boreal part with cool summers and relatively severe winters (coincides with the taiga) and the southern subboreal part with warm summers and relatively mild winters. According to the degree of continentality of the climate, expressed primarily by the annual temperature amplitude, its varieties are distinguished: from moderately continental to sharply continental. Humidification varies from excessive in the north to sharply insufficient in the south. Therefore, there is a rich range of natural vegetation zones: taiga, mixed and broad-leaved forests, forest-steppes, steppes, semi-deserts, deserts.

The climate of the western coasts of the continents is formed under the influence of the MW formed over warm currents and brought by those in power westerly winds. Therefore, it is called maritime climate. It is characterized by cool summers (+10°С in the north, +17°С in the south), mild winters with temperatures from 0 to +5°С. In winter, in the north, temperatures often drop to negative values, snowfalls. There is a lot of precipitation - 800-1000 mm, in front of the mountains up to 1500 mm (southwest of Scandinavia) and even 3000 mm (western slopes of the Cordillera and Andes). Predominant precipitation is frontal and orographic. Humidification is excessive. Coniferous and deciduous forests grow.

The climate of the eastern coasts of Asia is monsoonal. There is a seasonal change of air masses here: warm and humid MUH in summer, very cold and dry SHW from the Asian High in winter. Accordingly, the temperature is about +20°C in summer and -10... -20°C in winter. The amount of summer precipitation is 10-20 times more than winter precipitation, and their total amount varies from 500 to 1000 mm depending on the orography: there is more precipitation on the eastern slopes of the mountains. Humidification is excessive, mixed and coniferous forests. A similar climate is best expressed in the Primorsky Territory of Russia and Northeast China. In North America, the circulation of air masses is monsoonal, but the climate is uniformly humid.

The oceanic climate is expressed in the north of the Atlantic and Pacific Ocean and in the southern hemisphere. In summer the temperature is about + 12...+ 15°С, in winter +5... +8°С. Precipitation falls throughout the year, their annual amount is about 1000 mm. In the southern hemisphere, in the temperate zone, an oceanic climate dominates almost completely with cool summers, mild winters, heavy frontal precipitation, westerly winds, and unstable weather (“roaring” forties latitudes). Temperatures here are lower than in the northern hemisphere.

69 Question. Classification of climates B.P. Alisov (subarctic, arctic, antarctic).

Answer:

Subarctic and subantarctic belts. They are characterized by a seasonal change of air masses: in summer, HC is common, in winter - AB.

Continental, including sharply continental, climate is observed only in the northern hemisphere in the north of Eurasia and North America. Monsoon air circulation. In summer, AB comes from the Arctic Ocean, which, under the conditions of a polar day, transforms into SH. In winter, from the baric Asian and Canadian maxima, southerly winds bring very cold SW, which cools even more during the polar night and acquires the properties of SW. Summer is short, cool, with temperatures less than +10...+12°С and damp. Winter is severe (-40...-50°C), long, with little snow. In this belt - in Yakutia in the intermountain basin - there is a cold pole of the northern hemisphere - the village. Oymyakon, where a winter temperature of -71°C was recorded. The belt is characterized by large annual temperature amplitudes - up to 60-70°C. Precipitation - 200-100 mm, frontal - on the Arctic (Antarctic) front. Permafrost, excessive moisture, and large swampiness are widespread. Of the zones, tundra and forest-tundra are typical.

The maritime (oceanic) climate is found in the north of Europe, in the coastal seas of the Arctic Ocean (Barents, Greenland Seas), around Antarctica. Cool summers (+3...+5°С), floating sea and continental ice, and relatively mild (–10...–15°С) winters are typical. Precipitation - up to 500 mm, fogs are constant. Tundra stretches along the coasts of the northern continents and on the islands. In the southern hemisphere, on the islands around Antarctica, there are meadows with sparse grassy vegetation.

Arctic and Antarctic belts. They are dominated by a continental climate: in Antarctica, in Greenland, on the islands of the Canadian archipelago. Temperatures are below zero throughout the year. In Antarctica, at the Vostok inland station, at an altitude of more than 3 km, an absolute minimum temperature of -89.2°C was recorded. Precipitation - less than 100 mm. Ice deserts are typical. The oceanic climate is observed mainly in the Arctic. The temperatures here are negative, but during the polar day they can reach +2°C. Precipitation is 100-150 mm, but when cyclones penetrate there, they become more. The islands are characterized by tundra with a sparse moss-lichen cover.

The climate plays a huge role in the nature of the Earth. It depends on the moisture content of the area. It determines the nature of vegetation, wildlife, soil cover, the regime of rivers, lakes, seas, glaciers, the formation of certain rocks, and affects the formation of relief. The climate must be taken into account economic activity people, especially in agriculture, as well as in construction, industry, transport. Climate and weather are great importance for human health and activity.

70 Question. Optical phenomena in the atmosphere (halos, rainbows, glories, crowns, halos)