Tree Bud, Freezing Rain and Sleet

February 01, 2010


Photographer: Lee Anne Willson; Iowa State Website
Summary Author: Lee Anne Willson

Freezing rain and sleet fell over the U.S. Midwest recently, coating trees and making travel treacherous. This picture, taken on my driveway in Ames, Iowa, shows a bud of a maple tree that dropped after accumulating more weight in water from the freezing rain than it could manage. It fell on a bed of previously deposited sleet. These frozen ice pellets form when raindrops fall through a cold layer of air above the surface. Freezing rain or glaze forms when there's a temperature inversion (warm air above cold) so the rain stays liquid until it reaches a solid surface.  Freezing rain is especially hard on tree limbs and power lines, which have a high surface area to volume ratio. As I was taking this picture I heard frequent cracking noises across the neighborhood from limbs breaking off trees. Many areas lost power, although we were fortunate not to be among them. Photo taken on January 21, 2010.
Coordinates for Ames, Iowa  42.022911, -93.625208