On Tue, 6 Jan 2009 21:09:45 -0000, "Col"
wrote:


A slight (almost imperceptible?) increase in windspeed I would
imagine may be all that's required to stir up the coolest air near
the ground with slightly 'warmer' air aloft.

Useful! After that rise it has descended lower and now reads -6.9C

I checked back a few days using the graphs and noted that on the three
recent cold nights it also wobbled around a bit and was never a
straight line. In fact,it is showing another slight increase as I
write. The anenometer has shown just a tad of movement, not that I
have been out watching mind you.

R