A weather map is full of all kinds of different colored lines that mark the boundaries of different air masses. Advancing cold air is indicated as a blue line with triangles on it. Behind this line is the colder air and out ahead of the cold front is a warmer air mass.
The points of the triangle indicate which direction the colder air is moving. Cold fronts can bring rapid temperature changes to a region in a short period of time. It is not uncommon for the temperature to drop 20 degrees in just a few minutes.
Thunderstorms can develop along or ahead of the front, which can produce large hail and tornadoes. A red line with half circles on it indicates advancing warm air. The warmer air mass is behind the red line. The weather associated with a warm front can vary. In the winter out ahead of the warm front, low clouds, drizzle, fog, freeing rain and snow can develop.
This occurs due to warm air overrunning the cold air at the surface. In summer, a warm front can develop elevated thunderstorms. A stationary front has very little movement at all. The blue triangles point to the warmer air and the half circles face the colder air. Then finally there’s the occluded front, which is a pinkish color and means a cold front has overtaken a warm front.