instruction: What is Freezing Rain?
response: Freezing rain occurs when snowflakes descend into a warmer layer of air and melt completely. When these liquid water drops fall through another thin layer of freezing air just above the surface, they don't have enough time to refreeze before reaching the ground. Because they are “supercooled,” they instantly refreeze upon contact with anything that that is at or below freezing (32 degrees F), creating a glaze of ice on the ground, trees, power lines, or other objects. Even light accumulations can cause dangerous travel, while heavier amounts can cause significant damage to trees and power lines.  A significant accumulation of freezing rain lasting several hours or more is called an ice storm.