Warm front

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Representation of a warm front passage

The warm front , like the cold front , is a weather phenomenon in connection with a low pressure area . Warm and therefore lighter air masses slide onto the heavier, cold air masses in front of them in the direction of pull. The weather events are generally calmer than on cold fronts. In the area of ​​the rising warm air masses, cirrus clouds form first , followed by cirrostratus , altostratus and then nimbostratus clouds . The usually steady and long-lasting land rain begins when the sun is completely covered by the Altostratus. Moderate or heavy rain then falls from the nimbostratus. In summer there can also be thunderstorms of warm air .

Warm front symbol on weather maps

On a weather map , warm fronts are marked by red semicircles, which point in the direction of migration.

The air pressure is slightly falling in front of the warm front, falling behind it increasingly, the temperature rises with the arrival of the warm front (see diagram above). The wind usually turns back before the warm front (for example from south to south-east). After passing through the front, a clear change in wind direction can be felt, in the northern hemisphere due to the Coriolis force, turning clockwise, for example from south to south-west.

In a low pressure vortex, the warm front moves in front of the cold front. The cold front finally overtakes the warm front due to its higher speed. When sliding on the hot air, the warm front continuously loses momentum as these when sliding on in potential energy is converted. Due to the loss of kinetic energy, the warm front becomes slower and slower, while the cold front largely maintains its initial speed.

The warm sector lies between the warm and cold front . Occlusion is created in the area where both air masses merge .