The atmosphere is a layer of various gases around Earth that is held by the gravitational force of the planet. It has been formed by the activity over millions of years. Atmosphere regulates temperature and prevents the harmful rays from Sun from entering the biosphere of the planet, thereby providing the livable environment for organisms. Ninety-nine percent of the weight of atmosphere is contained within 100 km distance from Earth. Temperature, pressure and content vary at different places in the atmosphere. According to properties, the atmosphere has been divided into five major layers.
|Atmosphere of Earth|
Troposphere is the layer of atmosphere that is closest to Earth. It is up to 7 km in Polar Regions and up to 16 km in equatorial regions with an average altitude of 12 km. 2he region constitutes for almost 80% of the mass of the atmosphere. The major climatic phenomena like wind, rain, snow falling, lightning and thunder all take place here. In this region, temperature falls with increase in height. The boundary of the layer is called Tropopause, a region marked by stability in temperature.
Stratosphere stretches between 10 km to 50 km from Earth, above Tropopause. The layer is marked for its lack of clouds and other features of weather. Stratosphere is the most suitable region for air transportation. Here, temperature rises with the increase in distance from the Earth. It also contains the Ozone layer which absorbs the ultraviolet rays and other harmful radiations from the Sun, thereby preventing them from reaching Earth. The Ozone layer stretches between 15 km and 30 km from Earth. It is because of the activity of Ozone layer the temperature in this region increases with altitude.
The layer above Stratosphere is called Mesosphere. The region extends from 50 km to 80 km above Earth. Mesosphere shows a drop in temperature according to the height. It is the coldest region of the atmosphere.
Thermosphere is located above Mesosphere above 80 km of height. This region has high temperature due to the energy from Sun. In Mesosphere, temperature increases according to height reaching as far as to 1500 degree Celsius. Mesosphere also constitutes most part of the Ionosphere as well. It is a region ionized by solar radiation and contains many electrically charged particles. The region is most suitable one for radio communication for it helps the propagation of radio waves.
The outermost layer of the atmosphere is called Exosphere. It stretches between 700 km and 1000 km above the planet. It merges with the outer space and the particles here constantly escape to the space.