Jeff, Mother Nature knows fluid mechanics as well as thermodynamics.
Last winter our low was -28F, air temperature not wind chill.
Wind chill affects play almost no role in the clustering of bees. The outer layer of bees act as insulation for the cluster, with the heat generated from within moving out. The temperature in the hive within a few inches of the cluster is the outside ambient temperature.
The cluster does not try to heat the hive space, they only heat the cluster's occupied space.
As I said, my hives sit on 2x6" frames, however since I live on the top of a hill, flat ground is hard to come by. Some hives sit a foot or so off the ground.
I have had hives blown over with the boxes spread all over and the hives survived temperatures below 0F for the overnight.
I am not telling anyone that they have to do anything, I am simply explaining what I do and why.
[size="1"][ November 05, 2005, 10:34 AM: Message edited by: MountainCamp ][/size]