Model Question and Answers for APSC | Discuss the concept of air mass and explain its role in macro-climatic changes.
Discuss the concept of air mass and explain its role in macro-climatic changes.
Ans: An air mass is a large volume of air in the atmosphere that is mostly uniform in temperature and moisture. Air masses can extend thousands of kilometres in any direction, and can reach from ground level to the stratosphere—16 kilometres (10 miles) into the atmosphere.
A body of air that resembles the characteristics of the surface under it is called an air mass. When a large body of air remains over an area for several days or weeks, the body of air may change its thermal and moisture properties according to the land or water under it. The air exchanges heat with the land or water, either warming or cooling until its temperature closely matches that of the surface below it. The body of air also gains or loses moisture depending on the temperature and moisture content of the surface.
There are four main types of air masses — polar maritime, polar continental air, tropical maritime air and tropical continental air. The masses are named and categorized based on their topographical location, which also dictates the temperature and effect the mass will have on a surrounding area if it moves.
Role in macro-climatic changes:
- Cold air masses are responsible for high pressure and stability conditions in temperate and sub-tropical regions
- Frontal rains on collision of warm and cold fronts: The interaction of cold and warm air masses gives rise to extratropical cyclones and associated rainfalls
- A hot dry airmass could give rise to devastating droughts as well as wildfires in temperate regions
- Changes in local temperature of a large region
- Brings rainfall on condensation
- Formation of cyclones and anti-cyclones
- Heat bursts which occur in post-rainfall situations