There are two main mechanisms in heating the Earth by the Sun: 1) solar energy is transmitted through the world space in the form of radiant energy; 2) the radiant energy absorbed by the Earth is converted into heat.

The amount of solar radiation received by the Earth depends on:

from the distance between the earth and the sun. Earth is closest to the Sun in early January, farthest in early July; the difference between these two distances is 5 million km, as a result of which, in the first case, the Earth receives 3.4% more, and in the second 3.5% less radiation than with an average distance from the Earth to the Sun (in early April and at the beginning of October);

on the angle of incidence of the sun's rays on the earth's surface, which in turn depends on geographical latitude, the height of the Sun above the horizon (changing during the day and seasons), the nature of the relief earth's surface;

from the conversion of radiant energy in the atmosphere (scattering, absorption, reflection back into space) and on the surface of the Earth. The average albedo of the Earth is 43%.

The picture of the annual heat balance by latitudinal zones (in calories per 1 sq. cm per 1 min.) Is presented in table II.

Absorbed radiation decreases towards the poles, while long-wave radiation practically does not change. The temperature contrasts that arise between low and high latitudes are softened by the transfer of heat by sea and mainly air currents from low to high latitudes; the amount of transferred heat is indicated in the last column of the table.

For general geographic conclusions, rhythmic fluctuations in radiation due to the change of seasons are also important, since the rhythm of the thermal regime in a particular area also depends on this.

According to the characteristics of the Earth's irradiation at different latitudes, it is possible to outline the "rough" contours of the thermal zones.

In the belt enclosed between the tropics, the rays of the Sun at noon fall all the time at a large angle. The sun is at its zenith twice a year, the difference in the length of day and night is small, the influx of heat in the year is large and relatively uniform. This - hot belt.

Between the poles and the polar circles, day and night can last more than a day separately. On long nights (in winter) there is a strong cooling, since there is no heat influx at all, but even on long days (in summer) the heating is insignificant due to the low position of the Sun above the horizon, the reflection of radiation by snow and ice and the waste of heat on melting snow and ice. This is the cold belt.

Temperate zones are located between the tropics and the polar circles. Since the Sun is high in summer and low in winter, temperature fluctuations are quite large throughout the year.

However, in addition to geographic latitude (hence, solar radiation), the distribution of heat on Earth is also influenced by the nature of the distribution of land and sea, relief, altitude above sea level, sea and air currents. If these factors are also taken into account, then the boundaries of the thermal zones cannot be combined with parallels. That is why isotherms are taken as boundaries: annual - to highlight the zone in which the annual amplitudes of air temperature are small, and the isotherms of the warmest month - to highlight those zones where temperature fluctuations are sharper during the year. According to this principle, the following thermal zones are distinguished on Earth:

1) warm or hot, bounded in each hemisphere by an annual +20° isotherm passing near the 30th north and 30th south parallels;

2-3) two temperate zones, which in each hemisphere lie between the +20° annual isotherm and the +10° isotherm of the warmest month (July or January, respectively); in Death Valley (California) the highest July temperature on the globe was + 56.7 °;

4-5) two cold zones, in which the average temperature of the warmest month in the given hemisphere is less than +10°; sometimes two areas of eternal frost are distinguished from cold belts with average temperature the warmest month is below 0°. In the northern hemisphere this inner part Greenland and possibly the area around the Pole; in the southern hemisphere, everything that lies south of the 60th parallel. Antarctica is especially cold; Here, in August 1960, at Vostok station, the lowest air temperature on Earth, -88.3°C, was recorded.

The relationship between the distribution of temperature on Earth and the distribution of incoming solar radiation is quite clear. However, a direct relationship between the decrease in the average values ​​of incoming radiation and the decrease in temperature with increasing latitude exists only in winter. In the summer, for several months in the area North Pole due to the longer day here, the amount of radiation is noticeably higher than at the equator (Fig. 2). If in summer the temperature distribution corresponded to the distribution of radiation, then summer temperature air in the Arctic would be close to tropical. This is not possible only because there is an ice cover in the polar regions (snow albedo in high latitudes reaches 70-90% and a lot of heat is spent on melting snow and ice). In its absence in the Central Arctic, the summer temperature would be 10-20°C, winter 5-10°C, i.e. a completely different climate would have formed, in which the Arctic islands and coasts could have been dressed with rich vegetation, if many days and even many months of polar nights (the impossibility of photosynthesis) had not prevented this. The same would be in Antarctica, only with shades of "continentality": summer would be warmer than in the Arctic (closer to tropical conditions), winter is colder. Therefore, the ice cover of the Arctic and Antarctic is more of a cause than a consequence. low temperatures at high latitudes.

These data and considerations, without violating the actual, observed regularity of the zonal distribution of heat on the Earth, pose the problem of the genesis of thermal belts in a new and somewhat unexpected context. It turns out, for example, that glaciation and climate are not an effect and a cause, but two different effects of one common cause: some kind of change natural conditions causes glaciation, and already under the influence of the latter, decisive climate changes occur. And yet, at least local climate change must precede glaciation, because for the existence of ice, quite certain conditions of temperature and humidity are needed. A local ice mass can affect the local climate, allowing it to grow, then change the climate of a larger area, giving it an incentive to grow further, and so on. When such a spreading "ice lichen" (Gernet's term) covers a huge area, it will lead to a radical change in the climate in this area.

Introduction

climate equatorial tropical geographical latitude

Travelers and navigators of antiquity drew attention to the difference in climates of those or other countries that they happened to visit. Greek scientists own the first attempt to establish the Earth's climate system. It is claimed that the historian Polybius (204 - 121 BC) was the first to divide the whole earth into 6 climatic zones- two hot (uninhabited), two temperate and two cold. At that time, it was already clear that the degree of cold or heat on earth depends on the angle of inclination of the incident sun's rays. From this arose the very word "climate" (clima - slope), denoting for many centuries a certain belt of the earth's surface, limited by two latitudinal circles.

In our time, the relevance of climate research has not faded away. To date, the distribution of heat and its factors have been studied in detail, many climate classifications have been given, including the Alisov classification, which is most used in the territory former USSR, and Köppen, which is widespread in the world. But the climate changes over time, so this moment climate research is also relevant. Climatologists study in detail climate change and the causes of these changes.

Target term paper: to study the distribution of heat on Earth as the main climate-forming factor.

Objectives of the course work:

1) To study the factors of heat distribution over the Earth's surface;

2) Consider the main climatic zones Earth.

Heat distribution factors

The sun as a source of heat

The Sun is the closest star to the Earth, which is a huge ball of hot plasma in the center of the solar system.

Any body in nature has its own temperature, and, consequently, its own intensity of energy radiation. The higher the radiation intensity, the higher the temperature. Having extremely high temperatures The sun is a very strong source of radiation. Processes take place inside the Sun, in which helium atoms are synthesized from hydrogen atoms. These processes are called nuclear fusion processes. They are accompanied by the release of a huge amount of energy. This energy causes the Sun to heat up to 15 million degrees Celsius at its core. On the surface of the Sun (photosphere) the temperature reaches 5500°C (11) (3, pp. 40-42).

Thus, the Sun radiates a huge amount of energy that brings heat to the Earth, but the Earth is located at such a distance from the Sun that only a small part of this radiation reaches the surface, which allows living organisms to comfortably exist on our planet.

Earth rotation and geographic latitude

Form the globe and its movement in a certain way affect the influx of solar energy to the earth's surface. Only part of the sun's rays fall vertically on the surface of the globe. When the Earth rotates, the rays fall vertically only in a narrow belt located at an equal distance from the poles. Such a belt on the globe is the equatorial belt. As you move away from the equator, the surface of the Earth becomes more and more inclined with respect to the rays of the Sun. At the equator, where the sun's rays fall almost vertically, the greatest heating is observed. Here is the hot belt of the Earth. At the poles, where the sun's rays fall very obliquely, eternal snow and ice lie. In mid-latitudes, the amount of heat decreases with distance from the equator, that is, as the sun's height above the horizon decreases as it approaches the poles (Fig. 1.2).

Rice. 1. The distribution of sunlight on the surface of the Earth during the equinoxes

Rice. 2.

Rice. 3. Rotation of the Earth around the Sun

If the earth's axis were perpendicular to the plane of the earth's orbit, then the inclination of the sun's rays would be constant for each latitude, and the conditions of illumination and heating of the earth would not change during the year. In reality, the earth's axis makes an angle of 66 ° 33 with the plane of the earth's orbit. This leads to the fact that, while maintaining the orientation of the axis in world space, each point on the earth's surface meets the sun's rays at angles that change during the year (Fig. 1-3). On March 21 and September 23, the sun's rays fall vertically over the equator at noon. equals night. These are the days of spring and autumnal equinoxes(Fig. 1). On June 22, the sun's rays at noon fall vertically over the parallel 23 ° 27 "N, which is called the northern tropic. Above the surface north of 66 ° 33" N. sh. The sun does not set below the horizon and the polar day reigns there. This parallel is called the Arctic Circle, and the date June 22 is the day summer solstice. The surface south of 66 ° 33 "S. latitude is not illuminated by the Sun at all and the polar night reigns there. This parallel is called the Antarctic Circle. On December 22, the sun's rays fall at noon vertically over the parallel 23 ° 27" S. sh., which is called the southern tropic, and the date December 22 is the day winter solstice. At this time, the polar night is set to the north of the Arctic Circle, and the polar day is set to the south of the Antarctic Circle (Fig. 2) (12).

Since the tropics and the polar circles are the boundaries of the change in the regime of lighting and heating of the earth's surface during the year, they are taken as the astronomical boundaries of the thermal zones on Earth. Between the tropics there is a hot zone, from the tropics to the polar circles - two temperate zones, from the polar circles to the poles - two cold belts. This regularity in the distribution of illumination and heat is actually complicated by the influence of various geographical regularities, which will be discussed below (12).

The change in the conditions of heating of the earth's surface during the year is the cause of the change of seasons (winter, summer and transitional seasons) and determines the annual rhythm of processes in the geographic envelope ( annual course soil and air temperature, life processes, etc.) (12).

The daily rotation of the Earth around its axis causes significant temperature fluctuations. In the morning, with the sunrise, the arrival of solar radiation begins to exceed the own radiation of the earth's surface, so the temperature of the earth's surface increases. The greatest heating will be observed when the Sun occupies the highest position. As the sun approaches the horizon, its rays become more inclined towards the earth's surface and heat it up less. After sunset, the flow of heat stops. Night cooling of the earth's surface continues until a new sunrise (8).

If the thermal regime geographical envelope determined only by the distribution of solar radiation without its transfer by the atmosphere and hydrosphere, then at the equator the air temperature would be 39 ° C, and at the pole -44 ° C. Already at a latitude of 50 °, a zone of eternal frost would begin. The actual temperature at the equator is 26°C, and at the north pole -20°C.

As can be seen from the data in the table, up to latitudes of 30° solar temperatures are higher than actual ones, i.e., in this part of the globe an excess solar heat. In the middle, and even more so in the polar latitudes, the actual temperatures are higher than the solar ones, i.e., these belts of the Earth receive additional heat in addition to the sun. It comes from low latitudes with oceanic (water) and tropospheric air masses in the course of their planetary circulation.

Comparing the differences between solar and actual air temperatures with maps of the Earth-atmosphere radiation balance, we will be convinced of their similarity. This once again confirms the role of heat redistribution in climate formation. The map explains why the southern hemisphere is colder than the northern: there is less advective heat from the hot zone.

The distribution of solar heat, as well as its assimilation, occurs not in one system - the atmosphere, but in a system of a higher structural level - the atmosphere and hydrosphere.

1. Solar heat is spent mainly over the oceans for water evaporation: at the equator 3350, under the tropics 5010, in temperate zones 1774 MJ / m 2 (80, 120 and 40 kcal / cm 2) per year. Together with steam, it is redistributed both between zones and within each zone between oceans and continents.
2. From tropical latitudes, heat with trade wind circulation and tropical currents enters equatorial latitudes. The tropics lose 2510 MJ/m 2 (60 kcal/cm 2) per year, and at the equator the heat gain from condensation is 4190 MJ/m 2 (100 or more kcal/cm 2) per year. Therefore, although in equatorial belt total radiation less tropical, it receives more heat: all the energy spent on the evaporation of water in the tropical zones goes to the equator and, as we will see below, causes powerful ascending air currents here.
3. Northern temperate zone from warm ocean currents coming from equatorial latitudes - the Gulf Stream and Kuroshio receives on the oceans up to 837 MJ / m 2 (20 or more kcal / cm 2) per year.
4. By western transfer from the oceans, this heat is transferred to the continents, where temperate climate is formed not up to a latitude of 50°, but much north of the Arctic Circle.
5. the North Atlantic Current and atmospheric circulation significantly warm the Arctic.
6. In the southern hemisphere, only Argentina and Chile receive tropical heat; The cold waters of the Antarctic Current circulate in the Southern Ocean.

How does the height of the sun above the horizon change throughout the year. To find out, remember the results of your observations of the length of the shadow cast by a gnomon (pole 1 m long) at noon. In September, the shadow was the same length, in October it became longer, in November - even longer, in the 20th of December - the longest. From the end of December, the shadow decreases again. The change in the length of the shadow of the gno-mon shows that throughout the year the Sun at noon is at different heights above the horizon (Fig. 88). The higher the Sun is above the horizon, the shorter the shadow. The lower the Sun is above the horizon, the longer the shadow. The Sun rises highest in the Northern Hemisphere on June 22 (on the day of the summer solstice), and its lowest position is on December 22 (on the day of the winter solstice).

Why surface heating depends on the height of the Sun. From fig. 89 it can be seen that the same amount of light and heat coming from the Sun, at its high position, falls on a smaller area, and at a low position, on a larger one. Which area will get hotter? Of course, smaller, since the rays are concentrated there.

Consequently, the higher the Sun is above the horizon, the more rectilinearly its rays fall, the more the earth's surface heats up, and from it the air. Then summer comes (Fig. 90). The lower the Sun above the horizon, the smaller the angle of incidence of the rays, and the less the surface heats up. Winter is coming.

The greater the angle of incidence of the sun's rays on the earth's surface, the more it is illuminated and heated.

How the Earth's surface heats up. On the surface of the spherical Earth, the sun's rays fall at different angles. The greatest angle of incidence of rays at the equator. It decreases towards the poles (Fig. 91).

Under greatest angle, almost vertically, the sun's rays fall on the equator. The earth's surface there receives the most solar heat, so it's hot near the equator all year round and there is no change of seasons.

The farther north or south from the equator, the lower the angle of incidence of the sun's rays. As a result, the surface and air are heated less. It gets cooler than at the equator. Seasons appear: winter, spring, summer, autumn.

In winter, the sun's rays do not fall at all on the poles and polar regions. The sun does not appear for several months from behind the horizon, and the day does not come. This phenomenon is called polar night . The surface and the air are very cold, so the winters there are very severe. In the same summer, the Sun does not set below the horizon for months and shines around the clock (the night does not come) - this polar day . It would seem that if summer lasts so long, then the surface should also heat up. But the Sun is low above the horizon, its rays only glide over the surface of the Earth and almost do not heat it. Therefore, summer near the poles is cold.

Illumination and heating of the surface depend on its location on Earth: the closer to the equator, the greater the angle of incidence of the sun's rays, the more the surface heats up. As you move away from the equator to the poles, the angle of incidence of the rays decreases, respectively, the surface heats up less and becomes colder.material from the site

In the spring, plants begin to flourish

The value of light and heat for wildlife. sunlight and heat are necessary for all living things. In spring and summer, when there is a lot of light and heat, the plants are in bloom. With the advent of autumn, when the sun above the horizon decreases and the flow of light and heat decreases, the plants shed their leaves. With the onset of winter, when the day is short, nature is at rest, some animals (bears, badgers) even hibernate. When spring comes and the Sun rises higher and higher, the plants begin active growth again, come to life animal world. And it's all thanks to the sun.

Ornamental plants such as monstera, ficus, asparagus, if they are gradually turned towards the light, grow evenly in all directions. But flowering plants do not tolerate this change well. Azalea, camellia, geranium, fuchsia, begonia drop buds and even leaves almost immediately. Therefore, during flowering, it is better not to rearrange "sensitive" plants.

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Video lesson 2: Atmosphere structure, meaning, study

Lecture: Atmosphere. Composition, structure, circulation. Distribution of heat and moisture on the Earth. Weather and climate

Atmosphere

atmosphere can be called an all-pervading shell. Its gaseous state allows filling microscopic holes in the soil, water is dissolved in water, animals, plants and humans cannot exist without air.

The nominal thickness of the shell is 1500 km. Its upper boundaries dissolve into space and are not clearly marked. Atmospheric pressure at sea level at 0°C is 760 mm. rt. Art. The gas envelope is 78% nitrogen, 21% oxygen, 1% other gases (ozone, helium, water vapor, carbon dioxide). The density of the air shell changes with elevation: the higher, the rarer the air. This is why climbers can be oxygen starved. At the very surface of the earth, the highest density.

Composition, structure, circulation

Layers are distinguished in the shell:

Troposphere, 8-20 km thick. Moreover, at the poles the thickness of the troposphere is less than at the equator. About 80% of the total air mass is concentrated in this small layer. The troposphere tends to heat up from the surface of the earth, so its temperature is higher near the earth itself. With a rise up to 1 km. the temperature of the air envelope decreases by 6°C. In the troposphere, there is an active movement of air masses in the vertical and horizontal direction. It is this shell that is the "factory" of the weather. Cyclones and anticyclones form in it, western and east winds. All water vapor is concentrated in it, which condense and shed rain or snow. This layer of the atmosphere contains impurities: smoke, ash, dust, soot, everything we breathe. The boundary layer with the stratosphere is called the tropopause. Here the temperature drop ends.

Approximate boundaries stratosphere 11-55 km. Up to 25 km. There are slight changes in temperature, and higher it begins to rise from -56°C to 0°C at an altitude of 40 km. For another 15 kilometers, the temperature does not change, this layer was called the stratopause. The stratosphere in its composition contains ozone (O3), a protective barrier for the Earth. Due to the presence of the ozone layer, harmful ultraviolet rays do not penetrate the earth's surface. Lately anthropogenic activity has led to the destruction of this layer and the formation of "ozone holes". Scientists say that the cause of the "holes" is an increased concentration of free radicals and freon. Under the influence of solar radiation, the molecules of gases are destroyed, this process is accompanied by a glow (northern lights).

From 50-55 km. next layer starts mesosphere, which rises to 80-90 km. In this layer, the temperature decreases, at an altitude of 80 km it is -90°C. In the troposphere, the temperature again rises to several hundred degrees. Thermosphere extends up to 800 km. Upper bounds exosphere are not determined, since the gas dissipates and partially escapes into outer space.

Heat and moisture

The distribution of solar heat on the planet depends on the latitude of the place. The equator and the tropics receive more solar energy, since the angle of incidence of the sun's rays is about 90 °. The closer to the poles, the angle of incidence of the rays decreases, respectively, the amount of heat also decreases. The sun's rays, passing through the air shell, do not heat it. Only when it hits the ground, the sun's heat is absorbed by the surface of the earth, and then the air is heated from the underlying surface. The same thing happens in the ocean, except that water heats up more slowly than land and cools more slowly. Therefore, the proximity of the seas and oceans has an impact on climate formation. In summer sea ​​air brings us coolness and precipitation, warming in winter, since the surface of the ocean has not yet squandered its heat accumulated over the summer, and the earth's surface has quickly cooled. Marine air masses form above the surface of the water, therefore, they are saturated with water vapor. Moving over land, air masses lose moisture, bringing precipitation. Continental air masses form above the surface of the earth, as a rule, they are dry. The presence of continental air masses brings hot weather in summer, and clear frosty weather in winter.

Weather and climate

Weather- the state of the troposphere in a given place for a certain period of time.

Climate- the long-term weather regime characteristic of the area.

The weather can change during the day. Climate is a more constant characteristic. Each physical-geographical region is characterized certain type climate. The climate is formed as a result of the interaction and mutual influence of several factors: the latitude of the place, the prevailing air masses, the relief of the underlying surface, the presence of underwater currents, the presence or absence of water bodies.

On the earth's surface there are belts of low and high atmospheric pressure. Equatorial and temperate zones low pressure, at the poles and in the tropics the pressure is high. air masses moving out of the area high pressure to the low area. But as our Earth rotates, these directions deviate, in the northern hemisphere to the right, in the southern hemisphere to the left. From tropical zone trade winds blow to the equator, from the tropical zone to the temperate zone they blow westerly winds, polar easterly winds blow from the poles to the temperate zone. But in each belt, land areas alternate with water areas. Depending on whether the air mass formed over land or over the ocean, it can bring heavy rains or a clear sunny surface. The amount of moisture in air masses is affected by the topography of the underlying surface. Moisture-saturated air masses pass over the flat territories without obstacles. But if there are mountains on the way, heavy wet air cannot move through the mountains, and is forced to lose part, if not all, of the moisture on the slope of the mountains. East Coast Africa has a mountainous surface (Dragon Mountains). Air masses forming over Indian Ocean, saturated with moisture, but they lose all the water on the coast, a hot dry wind comes inland. That is why most South Africa busy with deserts.