Four kinds of Fronts
One type of front is a cold front. This happens when a fast moving cold air mass runs into a slow moving warm air mass. Cold air is denser than warm air so the cold air sinks to the ground and the warm air moves up. It is cold and can cause thunderstorms and snow storms. They cause cumulonimbus clouds. Another front is called a warm front. When it overtakes a cold front it slides above it and can cause light rain. They can cause regular clouds or cumulonimbus clouds.The third front is called a stationary front. It happens when a cold front and a warm front meet but neither has enough force to move one. This front causes some rain for many days. The final front is the an occluded front. This occluded front happens when 2 cold fronts move onto a warm front and push the warm front up. Expect light rain from this front.
What is a front?
It is the boundary between two air masses.