MemberMay 26, 2021 at 7:50 pm::
The blanket of gases that surrounds Earth is known as the atmosphere. Due to the earth’s gravitational attraction, it is held near the surface of the earth. There could be no life on Earth without the atmosphere. The atmosphere is responsible for keeping the climate moderate on earth as compared to other planets.
The atmosphere is divided into layers which has their respective temperature. These layers are the troposphere, stratosphere, mesosphere, and thermosphere.
The troposphere is the lowest part of the atmosphere where we live in. It constitutes the essential part of our weather – clouds, rain, snow, etc. In this layer of the atmosphere, the temperature depends on the distance above the earth. Air at the upper layer of the troposphere is cooler than the lower layer.
The lowest part of the troposphere is known as the boundary layer and the top of the troposphere is called the tropopause. It is found that tropopause is lowest at the poles and highest near the equator.
Up next layer is Stratosphere that extends upwards from the tropopause to about 50 km. It contains most part of the ozone layer in the atmosphere. Absorption of ultraviolet (UV) radiation from the sun occurs in this layer due to an increase in temperature with height. Temperatures can be found highest in the stratosphere over the summer pole, and lowest over the winter pole.
The mesosphere is the region above the stratosphere. The temperature decreases with height and can reach as low as about -90°C at the “mesopause”.
Thermosphere and Ionosphere
The thermosphere can be found just above the mesopause and is a region in which temperatures increases with height. The absorption of energetic ultraviolet and X-Ray radiation from the sun causes this rise in temperature. The ionosphere can be termed as the region of the atmosphere above about 80 km.
The next layer is the exosphere and it is termed as the region above about 500 km. It constitutes mainly of oxygen and hydrogen atoms. They follow “ballistic” trajectories under the influence of gravity as there are so few of them that they rarely collide. Some of the atoms even escape right out into space.
The last and outer region surrounding the earth, where charged particles spiral along the magnetic field lines, is called the magnetosphere. It traps electrons and protons, concentrating them in two bands about 3,000 and 16,000 km above the globe called the Van Allen “radiation” belts.