An air-mass is usually recognized as a large amount of air which as per meteorology has consistent distinctiveness like temperature, atmospheric pressure, and water vapor content. Air masses generally change as per the terrain and topography they are put to. An air mass can be best divided as per the category of temperature and moisture content.

The temperature defines air mass in terms of Arctic, Polar and Tropical, wherein Arctic is the coldest of the lot while the tropical is the warmest. Maritime and Continental are the terms by which one can define the moisture content of an air mass. Maritime air is usually known as moist air mass while the Continental air is dry in nature. The temperature and moisture combine top form the general air mass.

The air mass obtains the features of the terrain through which it moves and passes. Cold arctic air masses are popular in arctic regions and maritime air masses can be seen over water. Maritime air mass looses its moisture and with time becomes continental, just like the tropical air mass which shifts north and tends to take the properties of being polar or even arctic.

Perfect lines or borders don't identify air masses. Air masses are much different than microburst which has the tendency to move rapidly. When two or more air masses come in contact with each other within a small area, it is then known as weather front which brings in changes in the climatic conditions.