Air Masses and Weather Fronts
- Earth & Space
- Ages 11–14 · Grades 6–8
What you’ll find out
- Air masses take on the temperature and humidity of their source regions.
- Winds and jet streams move air masses, changing the local weather.
- Cold and warm fronts form where air masses meet and bring characteristic clouds and rain.
No sign-up and no real names. In the lesson you check your understanding as you read, and practise until it sticks.
Air masses
An air mass is an enormous body of air, sometimes covering thousands of kilometres, with roughly the same temperature and humidity throughout. It takes on the character of the region where it forms: air that sits over icy land becomes cold and dry, while air over a warm tropical ocean becomes warm and moist. Winds steer air masses across continents, and when a different air mass moves in, the local weather changes, sometimes within hours. Meteorologists watch these moving air masses closely.
Fronts bring changes
When two different air masses meet, they do not mix readily, and the boundary between them is called a front. At a cold front, dense cold air pushes under warmer air and forces it upwards steeply. The rising air cools rapidly, and its water vapour condenses into towering clouds that can bring heavy showers and thunderstorms, followed by cooler, clearer weather. At a warm front, warm air slides gently up over cold air, producing layers of grey cloud and long periods of steady rain.
Curriculum links: NGSS MS-ESS2-5 · Cambridge Lower Secondary Stages 7–9: Earth and space · NCERT Science, Classes 6–8