§ 28. Atmosphere (textbook)

§ 28. Atmosphere


Remember What is called natural air mixture.


Composition of air. Outside our planet is surrounded by a shell of air. From the earth's surface, it stretches up to several thousand kilometers. Therefore we can say that we live on the bottom of the ocean air. Aero shell called Earth atmosphere. Why not air scattered in outer space? Its gravity holds. Therefore atmosphere rotates with the Earth as a whole.

Atmospheric air - a mixture of gases. It consists of 20 different gases. But the main ones are nitrogen (78%) and oxygen (21%). For other accounts for only 1%. Such a composition gas almost everywhere on Earth equal to the height of 100 km.

Each emissions from fulfilling its role. Nitrogen part of the various compounds, which consist of all living beings. Oxygen all necessary live for breath. Carbon dioxide - "Insulation" of the Earth. To her he misses sunlight, and it retains heat. Ozone in an atmosphere of very little. But at an altitude of 20-30 km and it forms a concentrated ozone layer. This layer delays Ultraviolet rays, harmful to all living things.

Except that the air contained water vapor. Is it different and solid impurity: dust, ash from forest fires and volcanic eruptions, ice crystals and sea salt, soot. Thus, over the desert in the atmosphere much dust over the ocean - salt crystals over large cities - soot.

Lower below Earth's surface atmospheric feel. However, the air penetrates the pores and crack rocks. It is in the water soil, Live organisms. In an atmosphere of air is varied: the height of his number decreases. Approximately 50% of the air mass settles to height of 5 km, and almost all (99.5%) - to a height of 80 km. Near the surface, where gravity is stronger, denser and heavier air. From the height it becomes more rarefied. Therefore, a clear upper atmosphere has not. Conditionally its hold on altitude of 3000 km. There atmosphere is gradually moving into space.


Fig. Composition air


The structure of the atmosphere. How can consider the structure of the atmosphere, if outside air is transparent and does not vary its different parts? We found that density varies with height, content water vapor, temperature and other characteristics of air. With these features in atmosphere distinguish separate layers: troposphere, stratosphere, the upper layers.

Troposphere - Bottom (ground) layer atmosphere. Its thickness at the poles is 9 km in high latitudes - 11 km, above the equator - to 18 km. Troposphere is the most solid layer: it is concentrated in about 80% of the total air mass. In the troposphere is nearly all water pair, from which clouds are formed and then Air. Therefore, in the troposphere formed Earth's weather.

Stratosphere placed above the troposphere and extends to a height of 55 km. The air is very thin there. It has almost no impurities and water vapor. Because clouds are usually absent. At an altitude of 20-30 km concentrated ozone gas to form ozone. It absorbs deadly ultraviolet rays of the sun, harmful to all life on Earth.

У top atmosphere rarefied air so much that almost does not absorb solar heat and diffuses sunlight. Therefore, astronauts, flying there, see the sky is blue and black. They both shine and the Sun and stars. Extreme outer part of the atmosphere composed mainly of oxygen, helium and hydrogen. They can overcome gravity and "sneak" into space.


Fig. Structure atmosphere


Value atmosphere. Without the atmosphere of life on our planet would be impossible. With oxygen contained in the air, breathe all organisms on Earth. Only one person on day to about 11 000 liters (tank) air.

Atmosphere vberihaye Earth from overheating sunlight during the day and a strong cooling at night. Therefore, it is compared with invisible blanket that cover planet, keeping warm.

Clear air shell serves the Earth ... body armor vests. Yes, that air protects the Earth from meteorites. Most of them burns in the atmosphere, not dolitayuchy to the surface. This phenomenon - "falling stars" - well visible stellar summer night.

Study atmosphere. The study of atmospheric science deals meteorology. On the state of the atmosphere and it changes soon to know almost all men. But it is especially important for those working in transport (to the Navy, in aviation) in agriculture economy.

For observation of the atmosphere in various parts of the world are located  one thousand Meteorological stations. In hard to reach areas (high mountains, deserts, polar regions) are automatic station radiometeorolohichni. In the oceans they are installed on floating platforms (booth), held anchors. Investigate the atmosphere and also from research vessels.

In Nowadays, not only exploring the ground, but high layers. For this purpose apply special equipment. Up to 40 km climb balloons, which fixed to appliances. They note the temperature, humidity and movement air at different altitudes. Even higher, rising to 120 km meteorological rocket. Meteorological satellitesEquipped with TV and cameras from a height of 900 km transmit to Earth message cloudy limits of snow cover on surface air pollution.

Fig. Research vessel


Fig. Weather station


Questions and Tasks

1. Tell us about the composition of air.

2. Compare trope- and stratosphere. Name at least three differences between them.

3. Space ships flying at an altitude of 300 km. In atmosphere where they are at the same time? Tell us about the features of these layers.

4. How important is the atmosphere of our planet?

5. What ways and means of studying the atmosphere?

6. Why the troposphere is called "factory" weather?