Night before Christmas

Some think of Santa. I dream of Planck's Constant.

I put a steel bar outside on the roof at night, facing upward into the relatively clear sky (stars visible), compare its temp with the temp of a shielded sensor; you see, on December 23-24, 2007, a temp suppression of the bar of only about one degree. This is with a sky radiant temp (Radioshack sensor) of about 5 degrees and relatively high dew point of about 21 degrees. Notice the wave of humidity at about 2 to 4 am, dew point reaches close to air temp, so RH is close to 100 percent and the temp suppression becomes much less (in part because water begins to condense on the steel surface, creating heat.). Therefore we cannot get much radiant cooling under these circumstances of high air saturation.

It happens that I did not in my bed dreaming of sugar plums notice any suffocating wave of humidity at 2-4 am, perhaps it did not arise in the indoor environment. Why? Or was it the low temp, not over 23 degrees, that kept my body well below the point of perspiration? All worth investigating as the hot season approaches and the night temps hover up at around 30 rather than this month's more comfortable mid twenties.