Heat distribution over the earth's surface. Atmosphere. Composition, structure, circulation. Distribution of heat and moisture on the Earth. Weather and climate Height of the lower and upper bounds

Precipitation on our planet is distributed extremely unevenly. In some areas, it rains every day and so much moisture is supplied to the Earth's surface that rivers remain full-flowing all year round, and tropical forests rise in tiers, blocking the sunlight. But you can also find places on the planet where not a drop of rain falls from the sky for several years in a row, the dried-up beds of temporary water streams crack under the rays of the scorching Sun, and scarce plants can only reach deep layers of groundwater thanks to long roots. What is the reason for this injustice? The distribution of precipitation on the globe depends on how many clouds containing moisture form over a given area or how much the wind can bring. The air temperature is very important, because intensive evaporation of moisture occurs precisely at a high temperature. The moisture evaporates, rises and clouds form at a certain height.

The air temperature decreases from the equator to the poles, therefore, the amount of precipitation is maximum in the equatorial latitudes and decreases towards the poles. However, on land, the distribution of precipitation depends on a number of additional factors.

There is a lot of precipitation over coastal areas, and the amount decreases with distance from the oceans. There is more precipitation on the windy slopes of the mountain ranges and much less on the leeward slopes. For example, on the Atlantic coast of Norway in Bergen there are 1,730 mm of precipitation per year, and in Oslo (behind the ridge) only 560 mm. Low mountains also affect the distribution of precipitation - on the western slope of the Urals, in Ufa, an average of 600 mm of precipitation falls, and on the eastern slope, in Chelyabinsk, - 370 mm.

The distribution of precipitation is also influenced by the currents of the World Ocean. Over the areas near which warm currents pass, the amount of precipitation increases, since the air heats up from the warm water masses, it rises and clouds with sufficient water content are formed. Over the territories near which cold currents pass, the air cools down, descends, clouds do not form, and much less precipitation falls.

The largest amount of precipitation falls in the Amazon basin, off the coast of the Gulf of Guinea and in Indonesia. In some parts of Indonesia, their maximum values ​​reach 7000 mm per year. In India, in the foothills of the Himalayas, at an altitude of about 1300 m above sea level, there is the wettest place on Earth - Cherrapunji (25.3 ° N and 91.8 ° E), with an average of more than 11,000 mm of precipitation in year. Such an abundance of moisture is brought to these places by the humid summer southwestern monsoon, which rises along the steep slopes of the mountains, cools and pours into powerful rain.

Atmosphere pressure- the pressure of atmospheric air on the objects in it and the earth's surface. Normal atmospheric pressure is 760 mm Hg. Art. (101325 Pa). As the altitude rises, the pressure drops by 100 mm for every kilometer.

Atmosphere composition:

The Earth's atmosphere is the Earth's air shell, consisting mainly of gases and various impurities (dust, water droplets, ice crystals, sea salts, combustion products), the amount of which is variable. The main gases are nitrogen (78%), oxygen (21%) and argon (0.93%). The concentration of gases that make up the atmosphere is practically constant, with the exception of carbon dioxide CO2 (0.03%).

The atmosphere also contains SO2, CH4, NH3, CO, hydrocarbons, HC1, HF, Hg, I2 vapors, as well as NO and many other gases in small quantities. A large amount of suspended solid and liquid particles (aerosols) are constantly found in the troposphere.

Climate and weather

Weather and climate are intertwined, but it's worth identifying the difference between them.

Weather- This is the state of the atmosphere over a certain area at a certain point in time. In the same city, the weather can change every few hours: fog appears in the morning, a thunderstorm begins by lunchtime, and by the evening the sky clears of clouds.

Climate- long-term, repetitive weather regime, typical for a certain area. The climate affects the terrain, water bodies, flora and fauna.

The main elements of the weather are precipitation (rain, snow, fog), wind, air temperature and humidity, cloudiness.

Precipitation- This is water in liquid or solid form, falling to the surface of the earth.

They are measured using an instrument called a rain gauge. It is a metal cylinder with a cross-sectional area of ​​500 cm2. Precipitation is measured in millimeters - this is the depth of the water layer that appeared in the rain gauge after precipitation.

Air temperature is determined using a thermometer - a device consisting of a temperature scale and a cylinder partially filled with a certain substance (usually alcohol or mercury). The action of a thermometer is based on the expansion of a substance upon heating and contraction - upon cooling. One of the varieties of the thermometer is the well-known thermometer, in which the cylinder is filled with mercury. A thermometer that measures air temperature should be in the shade so that the sun's rays do not heat it up.

Temperature measurement is carried out at meteorological stations several times a day, after which the average daily, monthly average or average annual temperature is displayed.

The average daily temperature is the arithmetic mean of temperatures measured at regular intervals throughout the day. The average monthly temperature is the arithmetic average of all average daily temperatures during the month, and the average annual is the arithmetic average of all average daily temperatures during the year. In one locality, the average temperatures for each month and year remain approximately constant, as any large temperature fluctuations are offset by averaging. Currently, there is a trend towards a gradual increase in average temperatures, this phenomenon is called global warming. An increase in the average temperature by a few tenths of a degree is imperceptible to humans, but it has a significant impact on the climate, since along with the temperature, the pressure and humidity of the air change, and the winds also change.

Air humidity shows how saturated it is with water vapor. Measure the absolute and relative humidity. Absolute humidity is the amount of water vapor in 1 cubic meter of air, measured in grams. When people talk about weather, they often use relative humidity, which shows the percentage of water vapor in the air to the amount that is in the air at saturation. Saturation is a certain limit to which water vapor is in the air without condensing. Relative humidity cannot exceed 100%.

The saturation limit is different in different parts of the world. Therefore, to compare humidity in different areas, it is better to use an absolute indicator of humidity, and to characterize the weather in a certain area - a relative indicator.

Cloudiness usually estimated using the following expressions: cloudy - the entire sky is covered with clouds, partly cloudy - there are a large number of individual clouds, clear - the amount of clouds is insignificant or they are absent.

Atmosphere pressure is a very important characteristic of the weather. Atmospheric air has its own weight, and a column of air presses on every point of the earth's surface, on every object and living thing on it. Atmospheric pressure is usually measured in millimeters of mercury. To make such a dimension understandable, let us explain what it means. For every square centimeter of surface, air presses with the same force as a column of mercury 760 mm high. Thus, the air pressure is compared with the pressure of the mercury column. A figure less than 760 indicates low blood pressure.

Temperature fluctuations

In any locality, the temperature is not constant. Temperatures drop at night due to lack of solar energy. In this regard, it is customary to distinguish the average day and night temperatures. Also, the temperature fluctuates throughout the year. In winter, the average daily temperature is lower, gradually increasing in the spring and gradually decreasing in the fall, in summer the highest average daily temperature.

Distribution of light, heat and moisture over the earth's surface

On the surface of the spherical Earth, solar heat and light are unevenly distributed. This is due to the fact that the angle of incidence of the rays at different latitudes is different.

The earth's axis is inclined to the orbital plane at an angle. Its northern end is directed towards the North Star. The sun always illuminates half of the earth. At the same time, either the Northern Hemisphere is more illuminated (and the day lasts longer there than in the other hemisphere), then, on the contrary, the Southern. Twice a year, both hemispheres are illuminated in the same way (then the length of the day in both hemispheres is the same).

The sun is the main source of heat and light on Earth. This huge sphere of gas, with a surface temperature of about 6,000 ° C, emits a large amount of energy, which is called solar radiation. It heats up our Earth, sets the air in motion, forms a water cycle, creates conditions for the life of plants and animals.

Passing through the atmosphere, part of the solar radiation is absorbed, part is scattered and reflected. Therefore, the flow of solar radiation, coming to the surface of the Earth, gradually weakens.

Solar radiation arrives at the Earth's surface in a direct and diffuse manner. Direct radiation is a stream of parallel rays coming directly from the solar disk. Scattered radiation comes from all over the sky. It is believed that the supply of heat from the Sun per 1 hectare of the Earth is equivalent to burning almost 143 thousand tons of coal.

The sun's rays, passing through the atmosphere, heat it little. The atmosphere is heated from the surface of the Earth, which, absorbing solar energy, converts it into heat. Particles of air, in contact with a heated surface, receive heat and carry it into the atmosphere. This is how the lower atmosphere heats up. Obviously, the more solar radiation the Earth's surface receives, the more it heats up, the more the air heats up from it.

Numerous observations of the air temperature showed that the highest temperature was observed in Tripoli (Africa) (+ 58 ° С), the lowest - at Vostok station in Antarctica (-87.4 ° С).

Solar heat gain and air temperature distribution depends on the latitude of the location. The tropical region receives more heat from the Sun than the temperate and polar latitudes. The most heat is received by the equatorial regions of the Sun - the star of the Solar System, which is a source of an enormous amount of heat and dazzling light for the planet Earth. Despite the fact that the Sun is at a considerable distance from us and only a small part of its radiation reaches us, this is quite enough for the development of life on Earth. Our planet revolves around the Sun in an orbit. If you observe the Earth from a spacecraft throughout the year, you can see that the Sun always illuminates only one half of the Earth, therefore, there will be day, and on the opposite half at this time there will be night. The earth's surface receives heat only during the day.

Our Earth heats up unevenly. The uneven heating of the Earth is explained by its spherical shape, therefore, the angle of incidence of the sun's ray in different regions is different, which means that different parts of the Earth receive different amounts of heat. At the equator, the sun's rays fall vertically, and they greatly heat the Earth. The farther from the equator, the less the angle of incidence of the ray becomes, and, consequently, the less heat is received by these territories. The same power beam of solar radiation heats a much smaller area near the equator, since it falls vertically. In addition, rays falling at a lower angle than at the equator - penetrating the atmosphere, pass a longer path in it, as a result of which part of the sun's rays is scattered in the troposphere and does not reach the earth's surface. All this indicates that with distance from the equator to the north or south, the air temperature decreases, as the angle of incidence of the sunbeam decreases.

The distribution of precipitation on the globe depends on how many clouds containing moisture form over a given area or how much the wind can bring. The air temperature is very important, because intensive evaporation of moisture occurs precisely at a high temperature. The moisture evaporates, rises and clouds form at a certain height.

The air temperature decreases from the equator to the poles, therefore, the amount of precipitation is maximum in the equatorial latitudes and decreases towards the poles. However, on land, the distribution of precipitation depends on a number of additional factors.

There is a lot of precipitation over coastal areas, and the amount decreases with distance from the oceans. There is more precipitation on the windward slopes of the mountain ranges and much less on the leeward slopes. For example, on the Atlantic coast of Norway, Bergen receives 1,730 mm of precipitation per year, and only 560 mm in Oslo. Low mountains also affect the distribution of precipitation - on the western slope of the Urals, in Ufa, an average of 600 mm of precipitation falls, and on the eastern slope, in Chelyabinsk, - 370 mm.

The largest amount of precipitation falls in the Amazon basin, off the coast of the Gulf of Guinea and in Indonesia. In some parts of Indonesia, their maximum values ​​reach 7000 mm per year. In India, in the foothills of the Himalayas, at an altitude of about 1300 m above sea level, there is the wettest place on Earth - Cherrapunji (25.3 ° N and 91.8 ° E, here an average of more than 11,000 mm of precipitation falls) Such an abundance of moisture brings to these places the humid summer southwestern monsoon, which rises along the steep slopes of the mountains, cools and rains down heavily.

Oceans, whose water temperature changes much more slowly than the temperature of the earth's surface or air, have a strong mitigating effect on the climate. At night and in winter, the air over the oceans cools much more slowly than over land, and if oceanic air masses move over the continents, this leads to warming. Conversely, during the day and summer, the sea breeze cools the land.

The distribution of moisture on the earth's surface is determined by the water cycle in nature. Every second, a huge amount of water evaporates into the atmosphere, mainly from the surface of the oceans. Humid ocean air, sweeping over the continents, cools. The moisture then condenses and returns to the earth's surface in the form of rain or snow. Partly it remains in the snow cover, rivers and lakes, and partly returns to the ocean, where evaporation occurs again. This completes the hydrological cycle.

The distribution of precipitation is also influenced by the currents of the World Ocean. Over the areas near which warm currents pass, the amount of precipitation increases, since the air heats up from the warm water masses, it rises and clouds with sufficient water content are formed. Over the territories near which cold currents pass, the air cools down, descends, clouds do not form, and much less precipitation falls.

Since water plays an essential role in erosion processes, it thereby affects the movements of the earth's crust. And any redistribution of masses due to such movements in the conditions of the Earth rotating around its axis is capable, in turn, of contributing to a change in the position of the Earth's axis. During ice ages, sea levels drop as water accumulates in glaciers. This, in turn, leads to the proliferation of continents and an increase in climatic contrasts. A decrease in river runoff and a decrease in the level of the World Ocean prevent warm ocean currents from reaching cold regions, which leads to further climatic changes.

If the thermal regime of the geographic envelope 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. Already at latitude 50 0 N. and y.sh. the zone of eternal 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 30 0 solar temperatures are higher than actual, i.e. 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 temperatures, i.e. these belts of the Earth receive additional heat to the sun. It comes from low latitudes with oceanic (water) and tropospheric air masses during 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 hydrosphere.

Analysis of the distribution of heat in the hydrosphere and atmosphere allows us to draw the following generalizing conclusions:

• 1. The southern hemisphere is colder than the northern one, since there is less advective heat from the hot belt.
• 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 the equatorial ones. 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 belt from warm ocean currents coming from equatorial latitudes (Gulf Stream, Kurovivo), receives on the oceans up to 20 or more kcal / cm 2 per year.
• 5. Western transfer from the oceans transfers heat to the continents, where the temperate climate is formed not up to latitude 50 0, but much to the 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 ​​above zero temperature anomalies is located in the North Atlantic. It stretches from the tropics to 85 0 N. and from Greenland to the Yamal-Black Sea line. The maximum excess of actual temperatures over the mid-latitude reaches in the Norwegian Sea (up to 26 0 С). The British Isles and Norway are 16 ° C warmer, France and the Baltic Sea are 12 ° C warmer.

An equally large and pronounced area of ​​below zero temperature anomalies is formed in Eastern Siberia in January, centered in North-Eastern 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).

Heat distribution on the earth's surface on geographical maps using isotherms. There are maps of isotherms for 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 С) is observed not at the equator, but at 10 0 N. This warmest parallel is called the thermal equator.
• 2. In July, the thermal equator shifts to the northern tropic. The average temperature at this parallel is 28.2 0 С, and in the hottest regions (Sahara, California, Tar) it reaches 36 0 С.
• 3. In January, the thermal equator shifts to the southern hemisphere, but not as significantly as in July to the northern one. The warmest parallel (26.7 0 С) is on average 5 0 S, but the hottest regions are located 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. the temperature decreases towards the poles, and in the southern hemisphere it is more significant than in the northern one. The difference between the equator and the North Pole is 27 0 С in winter 67 0 С, and between the equator and the South Pole in summer 40 0 ​​С, in winter 74 0 С.
• 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 in terms of temperature is very homogeneous.
• 6. In the northern temperate zone, the course of the January isotherms is very complicated. Isotherm analysis reveals the following patterns:
  • - in the Atlantic and Pacific oceans, heat advection is significant, associated with the circulation of the atmosphere and hydrosphere;
  • - the land adjacent to the oceans - Western Europe and North-Western America - have a high temperature (0 0 С on the coast of Norway);
  • - the huge land mass of Asia is very cooled, on it closed isotherms outline a very cold region in Eastern Siberia, up to - 48 0 C.
  • - isotherms in Eurasia go not from West to East, but from northwest to southeast, showing that temperatures are falling in the direction from the ocean inland; the same isotherm passes through Novosibirsk as on Novaya Zemlya (-18 0 С). It is as cold on the Aral Sea as on Svalbard (-14 0 C). A similar picture, but somewhat weakened, is observed in North America;
• 7. The July isotherms are quite 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 land temperature, because it is heated by the Sun. In tropical latitudes, the influence of cold ocean currents along the western coasts of the continents (California, Peruvian, Canary, etc.) is noticeable, which cool the adjacent land and cause the deviation of isotherms towards the equator.
• 8. In the distribution of heat over the globe, the following two regularities are clearly expressed: 1) zoning, due to the figure of the Earth; 2) the sector, due to the peculiarities of the assimilation of solar heat by the oceans and continents.
• 9. The average air temperature at the level of 2 m for the entire Earth is about 14 0 С, January 12 0 С, July 16 0 С. The southern hemisphere is colder than the northern hemisphere in the annual output. The average air temperature in the northern hemisphere is 15.2 0 С, in the southern - 13.3 0 С. The average air temperature for the entire Earth coincides approximately with the temperature observed at about 40 0 ​​N. (14 0 C).

Video tutorial 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 it to fill microscopic holes in the soil, water is dissolved in water, animals, plants and humans cannot exist without air.

The conditional thickness of the envelope is 1500 km. Its upper boundaries dissolve in space and are not clearly marked. The atmospheric pressure at sea level at 0 ° C is 760 mm. rt. Art. The gas shell consists of 78% nitrogen, 21% oxygen, 1% other gases (ozone, helium, water vapor, carbon dioxide). The density of the air envelope changes with rise in height: the higher, the more rarefied the air. This is why climbers can experience oxygen deprivation. The very surface of the earth has the greatest 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. This small layer contains about 80% of the entire mass of air. The troposphere tends to heat up from the surface of the earth, therefore its temperature is higher near the earth itself. With a rise up 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 directions. It is this shell that is the "factory" of the weather. Cyclones and anticyclones are formed in it, westerly and easterly winds blow. All water vapor is concentrated in it, which condenses and sheds rain or snow. This layer of the atmosphere contains impurities: smoke, ash, dust, soot, everything we breathe. The layer bordering the stratosphere is called the tropopause. This is where the temperature drop ends.

Approximate boundaries stratosphere 11-55 km. Up to 25 km. There are minor changes in temperature, and above it begins to rise from -56 ° C to 0 ° C at an altitude of 40 km. Another 15 kilometers, the temperature does not change, this layer was called the stratopause. The stratosphere 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 claim that the cause of the "holes" is the increased concentration of free radicals and freon. Under the influence of solar radiation, gas molecules are destroyed, this process is accompanied by glow (northern lights).

From 50-55 km. the next layer begins - mesosphere, which rises to 80-90 km. In this layer, the temperature decreases, at an altitude of 80 km it is -90 ° С. In the troposphere, the temperature rises again to several hundred degrees. Thermosphere stretches up to 800 km. Upper bounds exosphere are not determined, since the gas is scattered 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 up. 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 happens in the ocean, except that water heats up more slowly than land and cools more slowly. Therefore, the proximity of seas and oceans affects the formation of the climate. In summer, the sea air brings us coolness and precipitation, in winter it warms, since the surface of the ocean has not yet spent its heat accumulated over the summer, and the earth's surface has cooled down quickly. 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, formed above the earth's surface, are usually dry. The presence of continental air masses brings hot weather in summer and clear frosty in winter.

Weather and climate

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

Climate- long-term weather regime typical for the given 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.

There are belts of low and high atmospheric pressure on the earth's surface. Equatorial and temperate belts of low pressure, at the poles and in the tropics, the pressure is high. Air masses move from high pressure to low pressure. But since 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 tropical zone to the equator, westerly winds blow from the tropical zone to the temperate zone, and polar east 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 has formed over land or over the ocean, it can bring heavy rains or a clear sunny surface. The amount of moisture in the air masses is influenced by the relief of the underlying surface. Moisture-saturated air masses pass over flat areas without obstacles. But if there are mountains on the way, heavy humid air cannot move through the mountains, and is forced to lose some, or even all of the moisture on the slope of the mountains. The east coast of Africa has a mountainous surface (Drakensberg Mountains). The air masses that form over the Indian Ocean are saturated with moisture, but all the water is lost on the coast, a hot dry wind comes inland. This is why most of southern Africa is deserted.