Gaseous layer of the earth- Atmosphere:

1. The earth is surrounded by a layer of gas is called the Atmosphere. It provides us with the air we breathe and protects us from the harmful effects of sun’s rays.
2. The atmosphere extends up to a height of about 1,600 kilometres. The atmosphere is divided into five layers based on composition, temperature and other properties. These layers starting from earth’s surface are called the troposphere, the stratosphere, the mesosphere, the thermosphere and the exosphere. 
3. Troposphere is the most important layer of the earth. Its average height is approx 13 km and 17 km measured from mid-latitude. contains approximately 75% of the atmosphere's mass and 99% of its water vapor and aerosols. All weather phenomena occurs in this layer only like rainfall, thunder storm, hail storm. The temperature decreases as we go up- 1 degree Celsius at 165m above.
4. Stratosphere is second layer of the atmosphere. Its average height is 50 km from the earth. Ozone layer lies in this layer. This layer is clean from clouds and hence, ideal way for flying planes. The temperature increases as we go up.
5. Mesosphere is the third layer of the atmosphere. It lies above the stratosphere. It extends up to the height of 80 km. Meteorites burn up in this layer on entering from the space.
6. Thermosphere is the layer where ionsphere is present and helpful in communication. In this layer, temperature rises rapidly as we go up. This layer extends from 80-400 km.
7. Exosphere is the upper most layer of the atmosphere, beginning at 500 to 1,000 kilometres (310 to 620 mi) above the Earth's surface, the atmosphere turns into space. This layer has very thin air. Light gases like helium and hydrogen float into the space from here.