1. Air Masses and
Fronts

2. Air Masses
Air masses are very large regions of air with the same weather.
They mostly form in the tropics and the polar regions.
Air masses are always on the move and they bring weather with them.

3. Air Masses Rainy Cloudy Cool Temperatures Rainy Cloudy
An air mass over Northern California.
Once the same air mass travels to Utah, what will the weather be?

4. Air Masses
There are two different types of air masses: warm air masses and cold air masses.

5. What do you think happens when air masses meet?

6. Fronts
When cold air masses and warm air masses meet they crash and form fronts.
A front is a boundary between air masses that have two different temperatures.
There are three different types of fronts.
Warm Fronts
Usually there is a light rain.
Cold Fronts
Dark storm clouds can bring violent weather.
Stationary Fronts
Rainy weather may persist for several days.

7. Warm Front
A warm front forms when a mass of light, warm air slides over a cold air mass.

8. Cold Front
A cold front forms as heavy, cold air pushes under a warm air mass. The warm air is pushed upward along a steep front.

9. Stationary Front
A stationary front is a boundary between air masses that does not move.