How Air Masses Form

An air mass is a large body of air with uniform temperature and humidity.

Although the moisture and temperature characteristics within an air mass are uniform, the actual weather within it may vary due to different processes acting on it in different areas. An air mass that’s clear in one area, for instance, may produce clouds in another area where it’s undergoing orographic lift. Different air masses will develop different types of weather. The type of weather depends on the characteristics of the air mass For example, in a stable air mass, the lifting of warm air may lead to the formation of stratiform clouds, while in an unstable air mass, it could result in the development of towering cumulonimbus clouds and thunderstorms.