1. The earth does not experience extremes of temperature as on other planets due to the presence of the atmosphere. 

2. The amount of water vapour in the atmosphere varies from place to place due to difference in temperature. 

3. The solid particles play an important role in the atmosphere because they act as nuclei for the condensation of water vapour around them. 

4. The troposphere lies closest to the Earth’s surface and contains all the water vapour, mostly dust particles and clouds. This layer is subjected to intense mixing due to both horizontal and vertical circulation. Thus, the temperature decreases with height in this layer. 

5. The stratosphere is crucial to life on the earth because the ozone layer present in it absorbs the harmful ultraviolet radiation of the sun. 

6. The ionosphere is suited to long distance communication because radio waves used for this purpose are reflected back to the earth by the electrically charged gas molecules in it. 

7. As a jet plane flies high in the sky, it leaves a white trail behind because moisture from the engine forms condensation tracks which are not disturbed due to lack of air movement at that height. 

8. The exosphere allows the gas molecules to easily escape into space due to lack of gravity. 

9. Solid dust particles present in the atmosphere act as a nuclei for change of water vapour into raindrops around them.They also scatter Sun’s radiation during Sunrise or Sunset, However, dust particles present in the lower layer of atmosphere may be harmful to us. They are the greatest health hazards.