On Fri, 3 Mar 2006 18:48:55 -0000, "David Mitchell"
wrote:

I was a bit disappointed with last nights min of -7.4, particularly as it
reached -5.3 by 2250.
I noticed that there were two main periods when the temp rose overnight,
between 2300 and 0220 and again from 0600 to 0650.
This seems to be a regular occurrence overnight, with the time around 0300
being common, as is 0600.
Have others noticed similar trends, is it local topography, or what else
might cause this?
I can rule out cloud and wind, as I was awake and working and nipped outside
now and again to check.
Incidentally, currently -3.6 at 1850.

Actually, David, I also get interesting 'ups' and 'downs' on my
readings and one of the first things I do when I get to work is to see
what the graph of the overnight scenario shows. There is no real
pattern for me here in Dorset- the factors (whatever they are) seem to
vary every night during this cold spell - sometimes coldest just after
midnight - sometimes coldest close to dawn. I am going for, how do I
say it, different layers of air temperature and more than that I
cannot say, being a novice in these matters!! Cloud cover is what I
thought was the main culprit. The boffins will quickly tell me (us)
what is what
Regards Robin