Gatesgarth: cold on the valley floor

I felt the cold coming down Scarth Gap when we reached the top of the trees on the way down. Then I noticed that the smoke from the farm was rising only to spread horizontally 20 metres up: evidence of a cloud inversion. The smoke is less dense that the air around it because it has been heated and has expanded to become less dense than the air around it. Hence it floats upwards. As it rises it willcool a bit. There must be a layer of warmer, less dense air above 20 metres. The smoke is no longer less dense so it can't rise. It's quite low for this to happen, I had been hoping for a proper cloud inversion but the humidity levels can't have been right even though there was a temperature inversion. Temperatures are supposed to go down as you go up in the atmosphere. The shadow of the fells is so deep in winter that sunlight cannot reach the valley floor to warm the lowest layer of air during the day. There was no wind to disturb the layers of air.