What they are, what they do, how the form, etc.
There are four different types of air masses
A cold front occurs when a cold air mass moves in on a warm air mass. The cold air slides under the warm air, and pushes the warm air up. The type of clouds that are formed during a cold front are mostly cumulus and cumulonimbus. The weather that occurs in a cold front is heavy winds and severe thunderstorms. Heavy rain and snowfall might also occur. There might only be cloudy skies if there is not much water vapor in the air. After a cold front passes the area, there is cold, dry air left behind.
A warm front occurs when a slow moving warm air mass collides with a cold air mass, and the warm air slides over the cold air. The type of clouds that form are mostly altocumulus, altostratus, cirrocumulus, cirrostratus, cirrus, cumulonimbus, nimbostratus, stratus, and stratocumulus. The type of weather that occurs in a warm front is rainy and foggy. There could be scattered clouds, or very cloudy skies. The air after a warm front passes is warm and humid.
A stationary front occurs when a warm air mass and a cold air mass meet, but neither has enough force the push the other one somewhere else. The type weather that occurs in a stationary front is rain, snow, fog, thunderstorms, and/or clouds. A stationary front can stay put over a area for days, so the weather can last that long.
An occluded front occurs when a warm air masses is caught between two cold air masses. The cold air keeps moving and pushes up the warm air. The type of weather that occurs here is cloudy and rainy or snowy. The air near the ground gets colder.