Atmosphere - air shell of land of 1300 km, representing a mixture of different gases. Conventionally, the atmosphere is divided into several layers. The nearest to Earth layer, the troposphere. It is life of humans and animals, are intensively natural processes, connected with the activity of the Sun, heat and water exchange between the atmosphere and the earth, the movement of air masses, climate change and weather. For this layer consistently go stratosphere, mesosphere, thermosphere and the exosphere. Starting from a height of 80 km, the earth's shell is called the ionosphere, as in this layer are strongly dissolvine molecules and ions of gases.
The main gases of the atmosphere are nitrogen (78,09%), oxygen (20,95%), argon (0,93%), carbon dioxide (0.03%) and a number of inert gases, which accounts for no more than a thousandth of a percent. In addition, the atmosphere contains various impurities - carbon monoxide, methane, hydrogen sulphide, chlorine, various derivatives of nitrogen and dustcoming into the lower layers of the atmosphere by emissions of the industrial enterprises, furnaces, exhaust gases of motor transport.
In the atmosphere is the dispersion of solar radiation caused by the molecules of air and the atmosphere of larger particles (dust, fog, smoke, and so on), which has helped to reduce its intensity.
The physical properties of the atmosphere - atmospheric pressure, temperature and humidity (see Air, Humidity, wind speed have a large impact on the living conditions and health of the person. Atmospheric pressure is created atmospheric layer on the surface of the Earth. This pressure at sea level on average 1,033 kg/cm2, or equal to the pressure of mercury height of 760 mm At rise above the Earth's surface atmospheric pressure drops about 1 mm RT. Art. on every 10-11 m rise. At altitudes above 3000 m have not adapted to the height of a person develops altitude sickness. Healthy people usually don't feel atmospheric pressure, as well as small fluctuations (up to 10-30 mm RT. Art.); more sudden changes in pressure can cause disease (see Barotrauma, Decompression illness (DCI).
The atmosphere is almost not heated by sunlight, temperature depends on the temperature of the Earth's surface, so coming to Earth layers have a higher temperature; as rising temperature decreases by about 0.6° 100 m rise. At the upper boundary of the troposphere, the temperature falls to -56 degrees. The processes occurring in the atmosphere, are of great importance for the formation of weather and climate (see).
When pressure is measured using the unit atmosphere.

Atmosphere (from the Greek. atmos - pairs, breathing, and sphaira - ball) is the envelope of air surrounding the earth. The life of man, animals and plants takes place in conditions of external natural environment - in the biosphere. The boundary of the atmosphere is at an altitude of about 1000 km of Gas composition of the atmosphere up to 80-100 km, almost the same as that at the Earth's surface, but above oxygen, and even higher and nitrogen are dissociated nuclear state. Up to a height of 1000 km of the atmosphere consists of atoms of nitrogen and oxygen, the area of the ionosphere extends significantly higher (K. E. Fedorov).
In the plane of the equator found two areas of radiation: the first at a height of about a thousand, and the second two thousand kilometers formed because of the capture of the earth magnetic field of the electrons and protons.
The main physical elements A.: pressure, temperature (table), the amount of water vapor, the movement of air. Chemical composition A.: oxygen, nitrogen, carbon dioxide and other gases. Due to intensive mixing of air A. the chemical composition remains fairly constant within a very great heights.

Atmospheric pressure and air temperature at different heights
(International standard atmosphere)

The atmosphere is conventionally divided into the troposphere and the stratosphere. The border between them is considered the level on which stops lowering of the temperature (see table). Troposphere - lower atmosphere together with the tropopause (the layer 2-8 km) extends to a height of 10-15 km Especially high biological importance is the layer of A. adjacent to the Earth at a height of about 2 km. To the natural processes taking place in the troposphere, include all processes, connected with the activity of the Sun, the climate (see), the movement of air masses, weather fluctuations of meteorological factors (temperature, humidity and so on). These fluctuations are gradually reduced as it rises high in the mountains, in flights on the aircraft) and almost disappear on the border with stratosphere (table.) due to the removal from the earth surface, receiving and reflecting a significant proportion of solar radiation.
Atmospheric pressure is the pressure of the air above this place, in the result of the influence of gravity on the air particles. At sea level it is an average of 1,033 kg/cm2, that corresponds to a pressure of mercury height of 760 mm with the drop in atmospheric pressure decreases and the partial pressure of oxygen in ambient air. In result, at altitudes above 3000 m in the human body are evolving phenomenon, called the high-altitude or mountain sickness (see Altitude sickness). To study the distribution of atmospheric pressure at any given time points with the same pressure connect on a map network Isobar, which differ from one another, for example, on 5 mbar pressure. The rate of change of atmospheric pressure was characterized barometric gradient, which is determined by the pressure difference one degree Meridian (or 111 km). Temporary (for example, daily) fluctuations of atmospheric pressure in this paragraph of the earth surface at the same time of the year are slim. Pressure fluctuations affect people suffering from rheumatism, cardiovascular disorders, etc.

Temperatures at different times of year and day in different points of the Earth's surface is different. This is determined by the annual and diurnal variation of temperature in this paragraph; on the map it shows isotherm lines connecting points of equal daily, monthly or annual temperature. The maximum recorded temperature on the Earth's surface +58 degrees (Death Valley, California), minimum -68°, in Antarctica -80 degrees. As the distance from the earth surface air temperature is gradually decreasing (table.) on average 0.6° for every 100 m rise. On the boundary of the troposphere and the stratosphere in our latitudes, it reaches -56 degrees. The temperature difference between the air horizontally and vertically, and at different times of the day and year accounts for the origin and direction of movement of air masses - winds. The higher the temperature, the more (ceteris paribus) water vapor is in A., and Vice versa. Of great importance proximity to bodies of water, the degree of soil moisture and precipitation, as they mostly are sources of water vapor in the atmosphere. As you rise up the amount of water vapor in the air decreases, which is explained mainly by a decrease its temperature.
At very low and at high temperatures, especially at high humidity, there are local and General disorder thermal regulation of the organism, which results can be osnaline and frostbite (at low temperatures), or the phenomenon of over-temperature until the thermal udara (at high temperature). High humidity at low temperatures causes enhanced returns, body heat, it hypothermia, at high temperature - full disorder of body heat exchange with the environment, because in these difficult conditions the body heat through conduction and radiation, but also by evaporation of moisture from the surface of the body. In this regard, reduced working capacity and potential thermal impacts.
The movement of air (wind) in the atmosphere occurring continuously due to the difference in atmospheric pressure at different points in the earth's surface, characterized by the direction and speed. The prevailing wind direction is taken into account when planning new industrial enterprises, cities, towns, and at the location of the individual buildings of the sanatorium, housing and so on). The latter, for example, is very important in the polar regions, where in order to avoid the snow drifts buildings tend to be located along the line of the direction of lords in the winter winds. Big hygiene is the wind speed. The wind increases heat loss from the surface of the human skin is stronger, the more his speed. As a result of this possible local disorders of regulation and the emergence in the cold season, colds and even frostbite from working outdoors. Some people wind can cause a number of vegetative disorders. On the other hand, sufficient speed wind alleviates hot climate and weather, facilitates evaporation of moisture from the skin surface, which significantly improves the well-being and can significantly affect the performance under these conditions.
The General circulation of the atmosphere is complex and constantly changing nature. In the vast spaces are formed and moving air masses, horizontal length of which sometimes reaches thousands of kilometers. Between adjacent air masses with different meteorological properties, formed many kilometers intermediate layers of air - fronts that all the time moves and changes. The passage of this or that front in a particular area is a sharp change of weather. The most humid fronts, apparently, can contribute to the development of colds.
Cm. also atmospheric electricity.