Snow Fog

February 5th, 2013 at 11:49 am by under Weather

Fog picture taken by Harlow Meek (Fort Wayne)

I’ve had a lot of questions and confusion about why we had fog Tuesday morning. Many thought there was no way to have fog with snow on the ground, or that it was too cold to have fog. Both of these assumptions are not correct, as proven this morning. In fact, I will argue that it is actually easier to have snow when there is a fresh snow cover on the ground.

Here’s what happened. The temperature fell to the wet bulb temperature or dew point temperature which caused 100% relative humidity or complete saturation. In fact, since the snow already consists of ice crystals we have the ingredients which make up a cloud. If you remember back to your old school days you might remember that fog is considered a cloud that is at ground level.

So fog can be present when snow is on the ground, it actually makes it easier to set the process of clouds making into motion.

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