With all the conversation lately about the lack of snow so far this winter, folks in the Red River Valley region forget that snow has fallen in many areas. Significant snows have fallen across portions of the Midwest and northern plains, with widespread snow cover in many areas. But where is the snow?
With the generally clear skies, satellite pictures this Friday morning have afforded us the opportunity to see just how widespread the snows are. Below are two satellite pictures; one visible the other Infrared. In the visible spectrum, the snow fields show up quite plainly, and the bare ground in the Valley Region is much darker.
As one may expect, the snowfields can cause significant modifications to the surface temperature. Meteorologists employ various wavelengths of the electromagnetic spectrum to observe weather systems. One such wavelength is in the infrared. Where the snow-cover is deep enough, it causes the near ground temperatures to be colder than bare ground. At night, under clear skies and light winds, the temperature can be tens of degrees colder. During the daytime, the snow reflects much more of the Suns incoming energy, and snow covered areas usually remain much colder than nearby areas without snow.
Below are excellent examples how how stark the variance can be with and without snow cover. In the visible picture, the snow covered areas are quite bright, and the bare ground in the Valley quite dark. Likewise in the infrared pictures the bare ground is darker (warmer) while the snow covered areas are colder (lighter color). East of the Red River Valley, much of north-central and northeastern Minnesota appears in a lighter color, even in the absence of snow-cover. This is due to the large forests, predominantly populated by a variety of pine trees (conifers).
Visible satellite picture of the Dakotas and Minnesota. Mainly clear skies afford a view of extensive snow cover over northern Iowa, southeast Minnesota and much of central North Dakota. Click for a larger view.
Infrared satellite picture of the Dakotas and Minnesota. Mainly clear skies afford a view of extensive snow cover over northern Iowa, southeast Minnesota and much of central North Dakota. Click for a larger view.