The atmosphere is the air envelope of the Earth, and in order to teach a geography lesson on this topic, there is a good presentation on 6th grade geography, which the World of Geography offered you to download, as usual, for free. During the lesson, 6th grade students learn a lot of interesting things about the atmosphere, about which they seem to be well aware. But in fact, the situation is such that they know about the composition of the air they breathe, but most likely they have not yet heard anything about the stratosphere. Therefore, there is a reason to download the presentation and, based on its slides, show and tell interesting information about the atmosphere.
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"sostavatm"
What does the atmosphere consist of? and how it works
Do you have a blanket, children?
So that the whole Earth is covered
So that there is enough for everyone,
And besides, it wasn’t visible?
Neither fold nor unfold,
Neither touch nor look?
It would let in rain and light,
Yes, but it seems not?!
Atmosphere - this is the air shell of the Earth
Atmospheric composition
OXYGEN. Oxygen reserves in the atmosphere are replenished by plants.
CARBON DIOXIDE. Carbon dioxide accumulates in the atmosphere as a result of volcanic eruptions, the respiration of living organisms and the combustion of fuels.
WATER VAPOR. Water vapor enters the air due to the evaporation of water.
Carbon dioxide, together with water vapor, “save” the heat of our planet: the atmosphere transmits more energy from the Sun to the earth’s surface than the Earth releases into the surrounding outer space.
OZONE. Ozone is formed from oxygen under the influence of sunlight and electrical discharges. It has a fresh smell, like what we smell after a thunderstorm. There is very little of this gas in the atmosphere, but at an altitude of 20-30 km there is a layer of air with a higher ozone content. It is called the ozone shield. It, like a shield, protects all living things from the destructive radiation of the Sun.
IMPURITIES. In addition to gases, there are also solid impurities in the atmospheric air. These small particles are formed as a result of the destruction of rocks, volcanic eruptions, dust storms, and fuel combustion. On the one hand, they pollute the air, but, on the other hand, without them clouds cannot form.
Troposphere is the lower layer of the atmosphere, extending to a height of 8-10 km above the poles, 10-12 km in mid-latitudes and 16-18 km above the equator.
There are more than 4 / 5 of all atmospheric air. Moreover, more than half of it is concentrated up to a height of 5 km. The air temperature here decreases with height and reaches -55 C at the upper limit. The troposphere contains almost all atmospheric moisture. Clouds form in it, bringing rain, snow, and hail. Here there is a constant movement of air, and wind is formed. Human and plant life takes place in the troposphere.
Stratosphere is a layer of the atmosphere lying above the troposphere up to an altitude of 55 km.
The air in the stratosphere is thinner than in the troposphere. Almost no clouds form in it, since there is very little water vapor. The air temperature here increases with height and at the upper limit is close to 0 °C.
Above the stratosphere, several more atmospheric layers are distinguished, which gradually turn into airless space.
Run the test
1. The atmosphere is a shell
A. Gas
b. Water
V. Salty
2. The lowest layer of the atmosphere:
A. Stratosphere
b. Troposphere
V. Upper atmosphere
Run the test
3. Oxygen in the air contains:
4. In the troposphere are formed:
A. Clouds
b. Ultra-violet rays
V. Groundwater
Definition Atmosphere (from ancient Greek τμός steam and σφα ρα ball) a gas shell surrounding planet Earth, one of the geospheres. Its inner surface covers the hydrosphere and partly the earth's crust, while its outer surface borders the near-Earth part of outer space. The set of branches of physics and chemistry that study the atmosphere is usually called atmospheric physics. The atmosphere determines the weather on the Earth's surface, meteorology studies weather, and climatology deals with long-term climate variations.
Boundary of the atmosphere The atmosphere is considered to be that region around the Earth in which the gaseous medium rotates together with the Earth as a single whole; With this definition, the atmosphere passes into interplanetary space gradually, in the exosphere, starting at an altitude of about 1000 km from the Earth’s surface; the boundary of the atmosphere can also be conventionally drawn at an altitude of 1300 km. According to the definition proposed by the International Aviation Federation, the boundary of the atmosphere and space is drawn along the Karman line, located at an altitude of about 100 km, where aeronautics becomes completely impossible. NASA uses 122 kilometers as the boundary of the atmosphere; recent experiments clarify the boundary of the Earth's atmosphere and ionosphere as being at an altitude of 118 kilometers.
Physical properties The total mass of air in the atmosphere is (5.15.3) 10 18 kg. Of these, the mass of dry air is (5.1352 ± 0.0003) 10 18 kg, the total mass of water vapor is on average 1.27 10 16 kg. The molar mass of pure dry air is 28.966 g/mol, the density of air at the sea surface is approximately 1.2 kg/m3. The pressure at 0 °C at sea level is 101.325 kPa; critical temperature 140.7 °C (~132.4 K); critical pressure 3.7 MPa; C p at 0 °C 1.0048 10 3 J/(kg K), C v 0.7159 10 3 J/(kg K) (at 0 °C). Solubility of air in water (by mass) at 0 °C 0.0036%, at 25 °C 0.0023%. The following are accepted as “normal conditions” at the Earth’s surface: density 1.2 kg/m3, barometric pressure 101.35 kPa, temperature +20 °C and relative humidity 50%. These conditional indicators have purely engineering significance.
The Earth's atmosphere arose as a result of two processes: the evaporation of matter from cosmic bodies as they fell to Earth and the release of gases during volcanic eruptions (degassation of the Earth's mantle). With the separation of the oceans and the emergence of the biosphere, the atmosphere changed due to gas exchange with water, plants, animals and the products of their decomposition in soils and swamps. Currently, the Earth's atmosphere consists mainly of gases and various impurities (dust, water droplets, ice crystals, sea salts, combustion products). The concentration of gases that make up the atmosphere is almost constant, with the exception of water (H 2 O) and carbon dioxide (CO 2). The water content in the atmosphere (in the form of water vapor) ranges from 0.2% to 2.5% by volume, and depends mainly on latitude. In addition to the gases indicated in the table, the atmosphere contains Cl 2, SO 2, NH 3, CO, O 3, NO 2, hydrocarbons, HCl, HF, HBr, HI, Hg vapor, I 2, Br 2, as well as NO and many other gases in small quantities. The troposphere constantly contains a large amount of suspended solid and liquid particles (aerosol). The rarest gas in the Earth's atmosphere is radon (Rn).
Structure of the atmosphere Boundary layer of the atmosphere The lower layer of the atmosphere adjacent to the Earth's surface (1-2 km thick) in which the influence of this surface directly affects its dynamics. Troposphere Its upper limit is located at an altitude of 810 km in polar, 1012 km in temperate and 1618 km in tropical latitudes; lower in winter than in summer. The lower, main layer of the atmosphere contains more than 80% of the total mass of atmospheric air and about 90% of the total water vapor present in the atmosphere. Turbulence and convection are highly developed in the troposphere, clouds arise, and cyclones and anticyclones develop. Temperature decreases with increasing altitude with an average vertical gradient of 0.65°/100 m Tropopause The transition layer from the troposphere to the stratosphere, a layer of the atmosphere in which the decrease in temperature with altitude stops. Stratosphere The layer of the atmosphere located at an altitude of 11 to 50 km. Characterized by a slight change in temperature in the 1125 km layer (lower layer of the stratosphere) and an increase in the 2540 km layer from 56.5 to 0.8 ° C (upper layer of the stratosphere or inversion region). Having reached a value of about 273 K (almost 0 °C) at an altitude of about 40 km, the temperature remains constant up to an altitude of about 55 km. This region of constant temperature is called the stratopause and is the boundary between the stratosphere and mesosphere. Thermopause The region of the atmosphere adjacent to the thermosphere. In this region, the absorption of solar radiation is negligible and the temperature does not actually change with altitude. Stratopause The boundary layer of the atmosphere between the stratosphere and mesosphere. In the vertical temperature distribution there is a maximum (about 0 °C). Mesosphere The mesosphere begins at an altitude of 50 km and extends to 8090 km. Temperature decreases with height with an average vertical gradient of (0.250.3)°/100 m. The main energy process is radiant heat transfer. Complex photochemical processes involving free radicals, vibrationally excited molecules, etc. cause atmospheric luminescence. Mesopause The transition layer between the mesosphere and thermosphere. There is a minimum in the vertical temperature distribution (about 90 °C).
Exosphere (scattering sphere) The exosphere is the scattering zone, the outer part of the thermosphere, located above 700 km. The gas in the exosphere is very rarefied, and from here its particles leak into interplanetary space (dissipation). Up to an altitude of 100 km, the atmosphere is a homogeneous, well-mixed mixture of gases. In higher layers, the distribution of gases by height depends on their molecular weights; the concentration of heavier gases decreases faster with distance from the Earth's surface. Due to the decrease in gas density, the temperature drops from 0 °C in the stratosphere to 110 °C in the mesosphere. However, the kinetic energy of individual particles at km altitudes corresponds to a temperature of ~150 °C. Above 200 km, significant fluctuations in temperature and gas density in time and space are observed. At an altitude of about km, the exosphere gradually transforms into the so-called near-space vacuum, which is filled with highly rarefied particles of interplanetary gas, mainly hydrogen atoms. But this gas represents only part of the interplanetary matter. The other part consists of dust particles of cometary and meteoric origin. In addition to extremely rarefied dust particles, electromagnetic and corpuscular radiation of solar and galactic origin penetrates into this space. Overview The troposphere accounts for about 80% of the mass of the atmosphere, the stratosphere for about 20%; the mass of the mesosphere is not more than 0.3%, the thermosphere is less than 0.05% of the total mass of the atmosphere. Based on the electrical properties in the atmosphere, the neutronosphere and ionosphere are distinguished. Depending on the composition of the gas in the atmosphere, homosphere and heterosphere are distinguished. The heterosphere is a region where gravity affects the separation of gases, since their mixing at such a height is negligible. This implies a variable composition of the heterosphere. Below it lies a well-mixed, homogeneous part of the atmosphere called the homosphere. The boundary between these layers is called the turbopause; it lies at an altitude of about 120 km.
Other properties of the atmosphere and effects on the human body Already at an altitude of 5 km above sea level, an untrained person experiences oxygen starvation and, without adaptation, a person’s performance is significantly reduced. The physiological zone of the atmosphere ends here. Human breathing becomes impossible at an altitude of 9 km, although up to approximately 115 km the atmosphere contains oxygen. The atmosphere supplies us with the oxygen necessary for breathing. However, due to the drop in the total pressure of the atmosphere, as you rise to altitude, the partial pressure of oxygen decreases accordingly. The human lungs constantly contain about 3 liters of alveolar air. The partial pressure of oxygen in alveolar air at normal atmospheric pressure is 110 mmHg. Art., carbon dioxide pressure 40 mm Hg. Art., and water vapor 47 mm Hg. Art. With increasing altitude, oxygen pressure drops, and the total vapor pressure of water and carbon dioxide in the lungs remains almost constant at about 87 mm Hg. Art. The supply of oxygen to the lungs will completely stop when the ambient air pressure becomes equal to this value. At an altitude of about 1920 km, the atmospheric pressure drops to 47 mm Hg. Art. Therefore, at this altitude, water and interstitial fluid begin to boil in the human body. Outside a pressurized cabin at these altitudes, death occurs almost instantly. Thus, from the point of view of human physiology, “space” begins already at an altitude of 1519 km.
Dense layers of air, the troposphere and stratosphere, protect us from the damaging effects of radiation. With sufficient rarefaction of air, at altitudes of more than 36 km, ionizing radiation (primary cosmic rays) has an intense effect on the body; At altitudes of more than 40 km, the ultraviolet part of the solar spectrum is dangerous for humans. As we rise to an ever greater height above the Earth's surface, phenomena familiar to us observed in the lower layers of the atmosphere, such as the propagation of sound, the emergence of aerodynamic lift and drag, heat transfer by convection, etc., gradually weaken and then completely disappear. air, sound propagation is impossible. Up to altitudes of km, it is still possible to use air resistance and lift for controlled aerodynamic flight. But starting from altitudes of km, the concepts of the M number and the sound barrier, familiar to every pilot, lose their meaning: the conventional Karman line passes there, beyond which the region of purely ballistic flight begins, which can only be controlled using reactive forces. At altitudes above 100 km, the atmosphere is deprived of another remarkable property - the ability to absorb, conduct and transmit thermal energy by convection (that is, by mixing air). This means that various elements of equipment on the orbital space station will not be able to be cooled from the outside in the same way as is usually done on an airplane, using air jets and air radiators. At this altitude, as in space generally, the only way to transfer heat is thermal radiation.
History of the formation of the atmosphere According to the most widespread theory, the Earth's atmosphere has had three different compositions throughout its history. Initially, it consisted of light gases (hydrogen and helium) captured from interplanetary space. This is the so-called primary atmosphere. At the next stage, active volcanic activity led to the saturation of the atmosphere with gases other than hydrogen (carbon dioxide, ammonia, water vapor). This is how a secondary atmosphere was formed. This atmosphere was restorative. Further, the process of formation of the atmosphere was determined by the following factors: leakage of light gases (hydrogen and helium) into interplanetary space; chemical reactions occurring in the atmosphere under the influence of ultraviolet radiation, lightning discharges and some other factors. Gradually, these factors led to the formation of a tertiary atmosphere, characterized by much less hydrogen and much more nitrogen and carbon dioxide (formed as a result of chemical reactions from ammonia and hydrocarbons).
Nitrogen The formation of a large amount of nitrogen N2 is due to the oxidation of the ammonia-hydrogen atmosphere by molecular oxygen O2, which began to come from the surface of the planet as a result of photosynthesis, starting 3 billion years ago. Nitrogen N2 is also released into the atmosphere as a result of denitrification of nitrates and other nitrogen-containing compounds. Nitrogen is oxidized by ozone to NO in the upper atmosphere. Nitrogen N 2 reacts only under specific conditions (for example, during a lightning discharge). The oxidation of molecular nitrogen by ozone during electrical discharges is used in small quantities in the industrial production of nitrogen fertilizers. Cyanobacteria (blue-green algae) and nodule bacteria, which form rhizobial symbiosis with leguminous plants, which can be effective green manures - plants that do not deplete, but enrich the soil with natural fertilizers, can oxidize it with low energy consumption and convert it into a biologically active form.
Oxygen The composition of the atmosphere began to change radically with the appearance of living organisms on Earth, as a result of photosynthesis, accompanied by the release of oxygen and the absorption of carbon dioxide. Initially, oxygen was spent on the oxidation of reduced ammonia compounds, hydrocarbons, the ferrous form of iron contained in the oceans, etc. At the end of this stage, the oxygen content in the atmosphere began to increase. Gradually, a modern atmosphere with oxidizing properties formed. Since this caused serious and abrupt changes in many processes occurring in the atmosphere, lithosphere and biosphere, this event was called the Oxygen Catastrophe. During the Phanerozoic, the composition of the atmosphere and oxygen content underwent changes. They correlated primarily with the rate of deposition of organic sediment. Thus, during periods of coal accumulation, the oxygen content in the atmosphere apparently significantly exceeded the modern level.
Carbon dioxide The content of CO 2 in the atmosphere depends on volcanic activity and chemical processes in the earth's shells, but most of all on the intensity of biosynthesis and decomposition of organic matter in the Earth's biosphere. Almost the entire current biomass of the planet (about 2.4 10 12 tons) is formed due to carbon dioxide, nitrogen and water vapor contained in the atmospheric air. Organics buried in the ocean, swamps and forests turn into coal, oil and natural gas
Noble gases The source of the noble gases argon, helium and krypton are volcanic eruptions and the decay of radioactive elements. The Earth in general and the atmosphere in particular are depleted of inert gases compared to space. It is believed that the reason for this lies in the continuous leakage of gases into interplanetary space.
Atmospheric pollution Recently, humans have begun to influence the evolution of the atmosphere. The result of human activity has been a constant increase in the content of carbon dioxide in the atmosphere due to the combustion of hydrocarbon fuels accumulated in previous geological eras. Huge amounts of CO 2 are consumed during photosynthesis and absorbed by the world's oceans. This gas enters the atmosphere due to the decomposition of carbonate rocks and organic substances of plant and animal origin, as well as due to volcanism and human industrial activity. Over the past 100 years, the content of CO 2 in the atmosphere has increased by 10%, with the bulk (360 billion tons) coming from fuel combustion. If the growth rate of fuel combustion continues, then in the coming years the amount of CO 2 in the atmosphere will double and could lead to global climate change. Fuel combustion is the main source of polluting gases (CO, NO, SO 2). Sulfur dioxide is oxidized by atmospheric oxygen to SO 3, and nitrogen oxide to NO 2 in the upper layers of the atmosphere, which in turn interact with water vapor, and the resulting sulfuric acid H 2 SO 4 and nitric acid HNO 3 fall to the surface of the Earth in the form of t n. acid rain. The use of internal combustion engines leads to significant atmospheric pollution with nitrogen oxides, hydrocarbons and lead compounds (tetraethyl lead Pb(CH 3 CH 2) 4). Aerosol pollution of the atmosphere is caused by both natural causes (volcanic eruptions, dust storms, entrainment of drops of sea water and plant pollen, etc.) and human economic activities (mining ores and building materials, burning fuel, making cement, etc.). Intensive large-scale removal of particulate matter into the atmosphere is one of the possible causes of climate change on the planet.
History of origin The history of the origin and development of the atmosphere is quite complex and long, it dates back about 3 billion years. During this period, the composition and properties of the atmosphere changed several times, but over the past 50 million years, according to scientists, they have stabilized.
The mass of the modern atmosphere is approximately one millionth the mass of the Earth. With height, the density and pressure of the atmosphere sharply decrease, and the temperature changes unevenly and complexly, including due to the influence of solar activity and magnetic storms on the atmosphere. The change in temperature within the atmosphere at different altitudes is explained by the unequal absorption of solar energy by gases. The most intense thermal processes occur in the troposphere, and the atmosphere is heated from below, from the surface of the ocean and land.
Significance It should be noted that the atmosphere is of very great ecological importance. It protects all living organisms of the Earth from the harmful effects of cosmic radiation and meteorite impacts, regulates seasonal temperature fluctuations, balances and equalizes the daily cycle. If the atmosphere did not exist, the daily temperature fluctuation on Earth would reach ±200 °C.
The atmosphere is not only a life-giving “buffer” between space and the surface of our planet, a carrier of heat and moisture, photosynthesis and energy exchange, the main processes of the biosphere, also occur through it. The atmosphere influences the nature and dynamics of all exogenous processes that occur in the lithosphere (physical and chemical weathering, wind activity, natural waters, permafrost, glaciers).
The development of the hydrosphere also largely depended on the atmosphere due to the fact that the water balance and regime of surface and underground basins and water areas were formed under the influence of precipitation and evaporation. The processes of the hydrosphere and atmosphere are closely related.
Slide 2
What is atmospheric pressure?
Air, like all bodies around us, has mass. Scientists have calculated that a column of air presses on the Earth's surface with an average force of 1.03 kg per cm².
Slide 3
For the first time, atmospheric pressure was measured by the Italian scientist E. Torricelli using a mercury barometer. The pressure was determined by the height of the mercury column in the glass tube, which balances the corresponding air column in the atmosphere. And since then it has been customary to measure atmospheric pressure in mmHg.
Slide 4
Now there are more modern barometers, such as the aneroid barometer.
Slide 5
What atmospheric pressure is considered normal? It is generally accepted that atmospheric pressure measured at sea level in mid-latitudes at an air temperature of 0°C is considered normal and amounts to 760 mmHg.
Slide 6
If the readings are lower or higher than normal, then it is customary to say that the pressure is reduced (low) - denoted by the letter H, or increased (high) - denoted by the letter B.
Slide 7
So, what is atmospheric pressure?! Atmospheric pressure is the force with which air presses on the surface of the Earth and on all bodies located on it.
Slide 8
What does air pressure depend on?
As the altitude of the area increases, the pressure decreases. After all, at the same time, the column of air that presses on the surface of the Earth becomes smaller. Accordingly, if we descend into the lowlands, the pressure will increase.
Slide 9
In addition, if the temperature on the surface of the Earth is high, then the air heats up, it becomes lighter and rises upward - the pressure decreases, and if the air cools, it becomes heavier and denser, which means it sinks down - the pressure increases.
Slide 10
Why does the wind blow?
What happens during the day: - land, buildings on it, and from them the air heats up faster than water; - warm air rises above the land; - pressure over land decreases; - the air above the water does not have time, its pressure is still higher than above the land; - air from an area of higher pressure above the water tends to take place above the land and begins to move, equalizing the pressure. Conclusion: The wind blew from the sea to the land.
Slide 11
At night the opposite happens, i.e. the wind will blow from land to sea. The land and the air above it cools faster, and the pressure over the land becomes higher than over the water. Water cools more slowly, and the air above it remains warm longer. It rises and the pressure over the sea decreases. Such a wind, changing direction twice a day, is called a breeze.
Slide 12
Besides the breeze, there is another wind called monsoon. Its principle of direction of movement is the same as that of a breeze, only on a larger scale. It changes its direction 2 times a year in winter and summer. In summer it blows on land, and in winter on the ocean. This wind can be observed in Russia - the Far East.