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Distribution of sunlight and heat. Distribution of heat on the earth The inner shells of the Earth include

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, westerly and easterly winds blow. 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. Recently, 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, in winter warming, since the surface of the ocean has not yet spent its heat accumulated over the summer, and the earth's surface has quickly cooled down. 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 by a certain type of 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 of low pressure, high pressure at the poles and in the tropics. Air masses move from an area of ​​high pressure to an area of ​​low pressure. But as our Earth rotates, these directions deviate, in the northern hemisphere to the right, in the southern hemisphere to the left. Trade winds blow from the tropics to the equator, westerly winds blow from the tropics to the temperate zone, and 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, the heavy moist air cannot move through the mountains, and is forced to lose some, if not all, of the moisture on the slopes of the mountains. The east coast of Africa has a mountainous surface (Dragon Mountains). The air masses that form over the Indian Ocean are saturated with moisture, but all the water is lost on the coast, and a hot dry wind comes inland. That is why most of southern Africa is occupied by deserts.

How long does it take the earth to complete one revolution around the sun? Why do the seasons change?

1. The dependence of the amount of light and heat entering the Earth on the height of the Sun above the horizon and the length of the fall time. Recall from the section "Earth - a planet in the solar system" how the Earth revolves around the Sun during the year. You know that due to the inclination of the earth's axis with respect to the plane of the orbit, the angle of incidence of the sun's rays on the earth's surface changes throughout the year.

The results of observations carried out with the help of a gnomon in the schoolyard show that the higher the Sun is above the horizon, the greater the angle of incidence of the sun's rays and the duration of their fall. In this regard, the amount of solar heat also changes. If the sun's rays fall obliquely, then the Earth's surface heats up less. This is clearly visible due to the small amount of solar heat in the morning and evening. If the sun's rays fall vertically, then the Earth heats up more. This can be seen in the amount of heat at noon.

Now let's get acquainted with the various phenomena associated with the rotation of the Earth around the Sun.

2. Summer solstice. In the Northern Hemisphere, the longest day is June 22 (Fig. 65.1). After that, the day stops lengthening and gradually shortens. Therefore, June 22 is called the summer solstice. On this day, the place where the sun's rays fall directly overhead corresponds to the parallel of 23.5 ° north latitude. In the northern polar region from latitude 66.5° to the pole, the Sun does not set during the day, the polar day is established. In the southern hemisphere, on the contrary, from the latitude of 66.5 ° to the pole, the Sun does not rise, the polar night sets in. The duration of the polar day and polar night ranges from one day in the Arctic Circle to half a year towards the poles.

Rice. 65. Location of the globe during the summer and winter solstices.

3. Autumn equinox. With further rotation of the Earth in its orbit, the northern hemisphere gradually turns away from the Sun, the day is shortened, and the solstice zone decreases during the day. In the southern hemisphere, on the contrary, the day lengthens.

The area where the sun does not set is shrinking. On September 23, the noon Sun at the equator is directly overhead, in the northern and southern hemispheres the solar heat and light are distributed equally, day and night are equalized throughout the planet. This is called the autumnal equinox. Now the polar day is ending at the North Pole, the polar night is beginning. Further, until the middle of winter, the region of the polar night in the northern hemisphere gradually expands to 66.5 ° north latitude.

4. Winter Solstice. On September 23, the polar night ends at the South Pole, the polar day begins. This will last until December 22nd. On this day, the lengthening of the day for the southern hemisphere and the shortening of the day for the northern hemisphere cease. This is the winter solstice (Fig. 65.2).

On December 22, the Earth comes into a state opposite to June 22. Ray of the Sun along the parallel 23.5° S falls steeply south of 66.5°S. polar region, on the contrary, the Sun does not set.

The parallel of 66.5 ° north and south latitudes, which limits the distribution of the polar day and polar night from the pole, is called the Arctic Circle.

5. Spring equinox. Further in the northern hemisphere, the day lengthens, in the southern hemisphere it shortens. On March 21, day and night on the entire planet are again equalized. At noon at the equator, the sun's rays fall vertically. The polar day begins at the North Pole, the polar night begins at the South Pole.

6. Thermal belts. We have noticed that the area in which the noonday Sun is at its zenith in the northern and southern hemispheres extends to a latitude of 23.5°. The parallels of this latitude are called the Tropic of the North and the Tropic of the South.
The polar day and polar night begin from the Northern and Southern polar circles. They pass along 66°33"N and 66()33"S. These lines separate the belts, which differ in the illumination of the sun's rays and the amount of incoming heat (Fig. 66).

Rice. 66. Thermal belts of the globe

There are five thermal zones on the globe: one hot, two temperate and two cold.
The space of the earth's surface between the Northern and Southern tropics is referred to as the hot zone. During the year, sunlight falls on this belt most of all, therefore there is a lot of heat. The days are hot all year round, it never gets cold and it never snows.
From the Tropic of the North to the Arctic Circle is the North Temperate Zone, from the South Tropic to the Antarctic Circle is the South Temperate Zone.
The temperate zones are in an intermediate position between the hot and cold zones in terms of day length and heat distribution. They clearly show the four seasons. In summer, the days are long, the sun's rays fall directly, so the summer is hot. In winter, the Sun is not very high above the horizon, and the sun's rays fall obliquely, in addition, the day is short, so it can be cold and frosty.
In each hemisphere, from the Arctic Circle to the poles, there are northern and southern cold zones. In winter, there is no sunlight for several months (up to 6 months at the poles). Even in summer, the Sun is low on the horizon and with a short day, so that the surface of the Earth does not have time to warm up. Therefore, the winter is very cold, even in summer the snow and ice on the surface of the Earth do not have time to melt.

1. Using a tellurium (an astronomical instrument for demonstrating the movement of the Earth and planets around the Sun and the daily rotation of the Earth around its axis) or a globe with a lamp, observe how the sun's rays are distributed during the winter and summer solstice, spring and autumn equinoxes?

2. Determine on the globe in which thermal zone is Kazakhstan located?

3. In a notebook, draw a diagram of thermal zones. Mark the poles, the polar circles, the northern and southern tropics, the equator and label their latitudes.

4*. If the Earth's axis with respect to the plane of the orbit made an angle of 60 °, then at what latitudes would the boundaries of the polar circles and tropics pass?

The temperature of the Earth's surface reflects the heating of the air in any particular area of ​​​​our planet.

As a rule, special devices are used to measure it - thermometers located in small booths. Air temperature is measured at least 2 meters above the ground.

Average surface temperature of the Earth

Under the average temperature of the Earth's surface, they mean the number of degrees not in any particular place, but the average figure from all points of our globe. For example, if in Moscow the air temperature is 30 degrees, and in St. Petersburg 20, then the average temperature in the region of these two cities will be 25 degrees.

(Satellite image of the temperature of the Earth's surface in the month of January with a scale of Kelvin values)

When calculating the average temperature of the Earth, readings are taken not from a specific region, but from all regions of the globe. At the moment, the average temperature of the Earth is +12 degrees Celsius.

Minimum and maximum

The lowest temperature was recorded in 2010 in Antarctica. The record was -93 degrees Celsius. The hottest point on the planet is the Deshte Lut desert, located in Iran, where the record temperature was + 70 degrees.

(average temperature for July )

Antarctica is traditionally considered the coldest place on Earth. Africa and North America are constantly competing for the right to be called the warmest continent. However, all other continents are also not so far away, lagging behind the leaders by only a few degrees.

Distribution of heat and light on Earth

Our planet receives most of its heat from a star called the Sun. Despite the rather impressive distance separating us, the reaching amount of radiation is more than enough for the inhabitants of the Earth.

(average temperature for January distributed over the surface of the earth)

As you know, the Earth constantly revolves around the Sun, which illuminates only one part of our planet. Hence the uneven distribution of heat over the planet. The Earth has an ellipsoidal shape, as a result of which the rays of the Sun fall on different parts of the Earth at different angles. This results in an imbalance in the distribution of heat on the planet.

Another important factor affecting the distribution of heat is the tilt of the earth's axis, along which the planet makes a complete revolution around the sun. This tilt is 66.5 degrees, so our planet is constantly facing the northern part towards the North Star.

It is thanks to this slope that we have seasonal and temporal changes, namely, the amount of light and heat, day or night, either increases or decreases, and summer is replaced by autumn.

If the thermal regime of the geographical shell was 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 0 С, and at the pole -44 0 С. and y.sh. a zone of perpetual frost would begin. However, the actual temperature at the equator is about 26 0 C, and at the north pole -20 0 C.

Up to latitudes of 30 0 solar temperatures are higher than the actual ones; in this part of the globe, an excess of solar heat is formed. In the middle, and even more so in the polar latitudes, the actual temperatures are higher than solar ones, i.e. these belts of the Earth receive additional heat from the sun. It comes from low latitudes with oceanic (water) and tropospheric air masses in the course of their planetary circulation.

Thus, 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 the hydrosphere.

An analysis of the distribution of heat in the hydrosphere and atmosphere allows us to draw the following general conclusions:

  • 1. The southern hemisphere is colder than the northern one, since there is less advective heat from the hot zone.
  • 2. Solar heat is spent mainly over the oceans to evaporate water. Together with steam, it is redistributed both between zones and within each zone, between continents and oceans.
  • 3. From tropical latitudes, heat with trade wind circulation and tropical currents enters equatorial latitudes. The tropics lose up to 60 kcal/cm 2 per year, and at the equator the heat gain from condensation is 100 or more cal/cm 2 per year.
  • 4. The northern temperate zone from warm ocean currents coming from the equatorial latitudes (Gulf Stream, Kurovivo) receives on the oceans up to 20 or more kcal / cm 2 per year.
  • 5. By western transfer from the oceans, heat is transferred to the continents, where a temperate climate is formed not up to a latitude of 50 0, but much north of the Arctic Circle.
  • 6. In the southern hemisphere, only Argentina and Chile receive tropical heat; The cold waters of the Antarctic Current circulate in the Southern Ocean.

In January, a huge area of ​​positive temperature anomalies is located in the North Atlantic. It extends from the tropic to 85 0 n. and from Greenland to the Yamal-Black Sea line. The maximum excess of actual temperatures over the average latitude is reached in the Norwegian Sea (up to 26 0 C). The British Isles and Norway are warmer by 16 0 С, France and the Baltic Sea - by 12 0 С.

In Eastern Siberia in January, an equally large and pronounced area of ​​negative temperature anomalies is formed with a center in Northeastern Siberia. Here the anomaly reaches -24 0 С.

In the northern part of the Pacific Ocean there is also an area of ​​positive anomalies (up to 13 0 C), and in Canada - negative anomalies (up to -15 0 C).

Distribution of heat on the earth's surface on geographical maps using isotherms. There are maps of isotherms of the year and each month. These maps fairly objectively illustrate the thermal regime of a particular area.

Heat on the earth's surface is distributed zonal-regional:

  • 1. The average long-term highest temperature (27 0 C) is observed not at the equator, but at 10 0 N.L. This warmest parallel is called the thermal equator.
  • 2. In July, the thermal equator shifts to the northern tropic. The average temperature on this parallel is 28.2 0 C, and in the hottest areas (Sahara, California, Tar) it reaches 36 0 C.
  • 3. In January, the thermal equator shifts to the southern hemisphere, but not as significantly as in July to the northern. The warmest parallel (26.7 0 C) on average is 5 0 S, but the hottest areas are even further south, i.e. on the continents of Africa and Australia (30 0 C and 32 0 C).
  • 4. The temperature gradient is directed towards the poles, i.e. temperature decreases towards the poles, and in the southern hemisphere more significantly than in the northern. The difference between the equator and the North Pole is 27 0 C in winter 67 0 C, and between the Equator and the South Pole 40 0 ​​C in summer and 74 0 C in winter.
  • 5. The temperature drop from the equator to the poles is uneven. In tropical latitudes, it occurs very slowly: at 1 0 latitude in summer 0.06-0.09 0 C, in winter 0.2-0.3 0 C. The entire tropical zone is very homogeneous in terms of temperature.
  • 6. In the northern temperate zone, the course of the January isotherms is very complex. Analysis of isotherms reveals the following patterns:
    • - in the Atlantic and Pacific oceans, heat advection associated with the circulation of the atmosphere and hydrosphere is significant;
    • - land adjacent to the oceans - Western Europe and North-West America - have a high temperature (0 0 C on the coast of Norway);
    • - the huge landmass of Asia is very cold, on it closed isotherms outline a very cold region in Eastern Siberia, up to - 48 0 C.
    • - isotherms in Eurasia do not go from West to East, but from northwest to southeast, showing that temperatures fall in the direction from the ocean deep into the mainland; the same isotherm passes through Novosibirsk as in Novaya Zemlya (-18 0 C). It is as cold on the Aral Sea as on Svalbard (-14 0 C). A similar picture, but somewhat in a weakened form, is observed in North America;
  • 7. The July isotherms are fairly straightforward, because The temperature on land is determined by solar insolation, and the transfer of heat over the ocean (Gulf Stream) in summer does not noticeably affect the temperature of the land, because it is heated by the Sun. In tropical latitudes, the influence of cold ocean currents along the western coasts of the continents (California, Peru, Canary, etc.) is noticeable, which cool the land adjacent to them and cause isotherms to deviate towards the equator.
  • 8. The following two regularities are clearly expressed in the distribution of heat over the globe: 1) zoning due to the figure of the Earth; 2) sectorality, due to the peculiarities of the assimilation of solar heat by oceans and continents.
  • 9. The average air temperature at a level of 2 m for the entire Earth is about 14 0 C, January 12 0 C, July 16 0 C. The southern hemisphere is colder than the northern one in the annual output. The average air temperature in the northern hemisphere is 15.2 0 C, in the southern - 13.3 0 C. The average air temperature for the entire Earth coincides approximately with the temperature observed at about 40 0 ​​N.S. (14 0 С).

If the thermal regime of the geographical envelope was determined only by the distribution of solar radiation without its transfer by the atmosphere and hydrosphere, then the air temperature at the equator 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., an excess of solar heat is formed in this part of the globe. 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. Consequently, although the total radiation in the equatorial zone is less than 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. The northern temperate zone receives up to 837 MJ/m 2 (20 or more kcal/cm 2) per year from warm ocean currents coming from equatorial latitudes - the Gulf Stream and Kuroshio.
  4. By western transfer from the oceans, this heat is transferred to the continents, where a 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.