We were socked in from Christmas Eve through sometime Christmas afternoon. I went outside to walk Zeke about 10 pm and could barely see our neighbor’s outdoor Christmas tree. Late Tuesday morning we went for a longer walk down Fouche Gap Road into Texas Valley. It was very foggy.

Do you see anything down there?

I estimated the visibility to be about 100 yards. Everything was evenly lighted; there appeared to be no shadows at all, anywhere. The sky was lighter directly overhead, but it was pretty light in all directions. That means to me that the fog was not very thick overhead, so more of the sunlight made it to the ground. Think about all of those photons from the sun, flying down into the clouds, bouncing around from water droplet to water droplet. As it turns out, a good fraction bounce into the same direction they were going, and a good fraction bounce backwards. Some of them go into other directions. Eventually, if the fog is thick enough, they get pretty well confused, going pretty much in all directions, and eventually finding their way out in almost every direction, up, down, sideways. If the fog is too thick, the ones that get too deep get lost and never find their way out. That’s why most clouds look white from pretty much any direction you look at them, but thick clouds look dark from below. From the top they are as white as any other cloud.

The fog got thinner as we walked down the mountain, until at the bottom, there was almost no fog.

Pretty clear down here

Down in the valley the visibility was pretty good. The shiny metal roof of a house is visible across the valley on the side of Rocky Mountain, if you know just where to look, and you hold you mouth just right. It was probably close to a mile away.  Looking back up, the top of Lavender Mountain was hidden. So up on the top of Lavender Mountain we had fog, but from down in the valley, we had clouds.