The air masses can be formed in the tropical, arctic, polar, equatorial and monsoon region.
Step-by-step explanation:
A certain volume of air that is actually defined by its vapor amount and temperature can be considered as air mass. It covers a huge area on the surface of Earth and takes up the features of the level below it. The masses can be categorized by its source area and latitude.
The air mass generating in the cold region is considered as arctic or polar air mass, the mass of warm region is the tropical mass, masses generating in monsoon time or region of monsoon is considered monsoon mass which is wet in nature. The classification of the mass determines its features and modifications.