That broad and dense portion of the atmosphere is called air mass, whose physical properties, especially the temperature and humidity, are almost the same in the horizontal plane. Air – masses are often extended to hundreds of kilometers.
The basis of the classification of the air – masses:
Air – masses found in the world are classified mainly on the following bases:
1. On the basis of nature of their region of origin.
2. On the basis of conversion of the air – masses.
On the basis of nature of their region of origin, the air – masses are divided into tropical and polar air – masses. These can again be continental and oceanic. These are again divided into two sub – classes: sea tropical, sea – polar and continental tropical and continental polar region air – masses. Based on these two characteristics, surface and water conditions and the heat of the air – masses,
The variants found in the world are shown by the following table:
Areas of main and secondary air – masses found in the world are shown through the following diagrarm: