07 August 2007

Mount Trempealeau

One more river fog photo

This one is the Mississippi River with Mt. Trempealeau (the largest sandbar on the river) taken from the Minnesota side, a few miles downriver from Winona Minn.

We get a considerable amount of fog throughout the bluffs that border the river here. I believe this is Radiation fog (fog formed by the cooling of land after sunset by thermal radiation in calm conditions with clear sky. The cool ground produces condensation in the nearby air by heat conduction. Radiation fogs occur at night, and usually do not last long after sunrise).

In the early spring we get Advection fog (fog caused by moist air flowing over snowpack). It happens when it gets warm one day and the air fills with moisture from the melting snow. The next morning all the bluff tops will be covered in hoarfrost, every tree, every dried weed stalk, every blade of grass. It is amazingly beautiful and haunting. I have a photo of a spruce tree covered in hoarfrost, I will have to try to find it and post it here...


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