Friday, April 23, 2010
Frost and Fog
Valley fog usually protects us from frost. That was not the case last night. Uncommonly clear skies and radiationial cooling combined to create fog and frost. Cold air sank to the ground with warmer air above it. Frost formed at and slightly above the ground. The higher warmer air remained above freezing and filled with fog. We sited our garden in a frost drain. Cold rolls downhill from left to right. The frost that formed on the welded wire fence is thicker on the right side.
The air was so filled with fog when we woke up that pictures were impossible. Sunlight first burned off the fog then the frost. Plant shadows preserved some frost. I wanted a close look at the frost on the wire fence but I remained inside. Foot prints on frozen grass turn black in the sunlight where my step breaks the frozen blades of grass. It was also cold outside making it much easier to take it all in from the relative warmth of the living room.
We have freeze warnings for tonight. What will become of all of that tender new growth pushed to an early start by our unseasonably warm daytime temperatures?