Tuesday, March 29, 2016

What is freezing rain?

Freezing rain is rain that falls into a shallow layer of cold air with temperatures at or below 0 degrees Celsius near the surface. When this rain becomes supercooled it can freeze when it comes into contact with trees, vehicles, powerlines, bridges, roads.

Formation of freezing rain 

1. Falling snow passes through a layer of warm air that completely melts the snow to become rain.

2. The rain continues to fall and passes through a shallow layer of cold air 
with temperatures at or below 0 degrees Celsius about 100 meters above the ground.

3. The cold air reduces the temperature of the raindrops to freezing point or below the freezing point of water but does not freeze the raindrops to ice; (this phenomenon is called supercooling, and the drops are called supercooled drops.)

4. As the supercooled drops continue to fall to the ground, they freeze forming a thin layer of ice on any surface that is in its path. 
For example, roads, bridges, power lines, trees branches, windshields.

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