Air mass
Topic: Air Masses, Fronts, Cyclones and Thunderstorms · NCERT: Class 11, Ch 9 "Atmospheric Circulation and Weather Systems"
Meaning
An air mass is a very large body of air. Across its whole width, its temperature and moisture change very little. It forms when air stays for a long time over one uniform surface, such as a vast ocean or a wide plain. Slowly the air takes on that surface's character: warm or cold, wet or dry. When an air mass moves away, it carries this character to new places and shapes their weather. Along the way it is heated or cooled from below and gains or loses moisture.
Example
In winter, very cold and dry air builds up over the snow-covered Siberian Plain in northern Asia. When this air spreads south in a slightly changed (modified) form, it brings cold waves to north India.
Don't confuse with
- Front: an air mass is the body of air itself. A front is the narrow boundary zone where two different air masses meet.
Related concepts
- Source region
- Maritime tropical air mass
- Continental tropical air mass
- Maritime polar air mass
- Continental polar air mass
- Continental arctic air mass