1. Description of a Warm Front

2. Description of a Warm Front
A warm front is created by a warm air mass moving into a cooler area.
Since the warm air is less dense than the cold air, it rises up over the cold air rather than pushing it aside as a cold front does.
As the air rises, it cools and water condenses out of it.

3. Description of a Warm Front
Examine the diagram on your sheet.
This will give you an indication of what an approaching warm front looks like.
A day or two before the arrival of a warm front, the previously clear skies get a few wispy cirrus clouds.
These clouds thicken, covering more of the sky.

4. Description of a Warm Front
They move lower until a layer of altostratus clouds covers the sky like a featureless grey blanket.
Eventually the clouds are so thick that rain or snow begins.
As the cloud base gets lower, the clouds become nimbostratus clouds.

5. Description of a Warm Front
If it is very cold, freezing rain or sleet might develop.
At about the time that the precipitation stops, the temperature rises.

6. Description of a Warm Front