Winter Ice Phenomena

Cold morning temperatures the last several days due to still air and fresh snow cover has resulted in some interesting cold weather phenomena across the region. 

Sun dogs and sun pillars have appeared in the Wisconsin sky the last several mornings. A sun dog or parhelion is a halo in the form of luminous spots that appear at roughly 22 degrees on both sides of the sun.  They are caused by the refraction of sunlight passing through ice crystals.   Below is an example of a sun dog near Ironwood Michigan. 

Sun dog example

Sun pillars have also appeared in the early morning sky. They are a bright column above or below the sun produced by the reflection of sunlight through ice crystals.  Most sun pillars are seen when the sun is low on the horizon, or just below it. 

Also, the cold temperatures of the last several weeks has allowed lake ice to become much more expansive across the western shallower waters of Lake Michigan.  Below is a MODIS high resolution satellite image taken on Saturday around 1040 am CST.   Lake ice is observed in the cloud free areas extending about 5 miles from shore, from just south of

Lake Ice Growth

Sheboygan to just north of Milwaukee.  The lake ice may become more expansive today due to the continued cold temperatures, however breezy southwest winds may cause some of the ice to break off and float into the slightly warmer, deeper waters of Lake Michigan, thereby slowly thinning and melting.

Here is the latest national MODIS high resolution image.


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