An air mass is a large body of air with similar pressure, temperature and humidity conditions. The weather changes when a different air mass moves over us. In some places at some times, air masses move quickly and often, causing the weather to change almost daily. In other places and times, air masses stay in one spot, causing the same weather for weeks or months in a row.
Air masses can be cold or warm, wet or dry based on where they form. They don't mix when they come in contact with each other because the air is always of varying densities. So a warm air mass will move above a cooler air mass, probably causing precipitation and storms. We call the edge of an air mass where it meets another a front or weather front.
Climate is the normal weather for a given place over a long period of time. Climates are based on the kinds of air masses usually found there.
Which of these is a description of a climate?
A
a heavy snowstorm
B
a cold air mass
C
mild summers and warm winters
D
partly cloudy with a chance of rain
C
mild summers and warm winters