Concerning the air temperature during snow. It should be remembered that
snow flakes experience the wet bulb temperature of the air, not the dry bulb
one. In a situation like today's, with the wet bulb potential temperature
in the boundary layer of -1.0 to -1.5 over southern UK, no precipitation in
a solid state on leaving the cloud will be able to melt before reaching the
ground. Also, conditions of strong insolation can produce a marked
superadibatic lapse rate near the ground, on top of which, radiation effects
on the measuring probe or thermometer, be it in a screen or other shield,
can lead to snow being observed with reported air temperatures of +8 or so.

--
Bernard Burton
Wokingham, Berkshire, UK.

Satellite images at:
www.woksat.info/wwp.html
or
www.btinternet.com/~wokingham.weather/wwp.html
"Len Watts" wrote in message
...
The other thing I would like to know is why was it snowing here with a
temperature of +3c when had it have been January, it would have been rain
at
that temperatuure.

I have noted this on a number of occasions, in other words it never seems
to
have to be so cold for spring snow as it does for winter snow. Anyone out
there know the reasons why?

Regards.
Len.

"Scott W" wrote in message
...
I was wondering if today's proceedings constituted a proper polar low.

It seems that the snow arrived in the South East at just the right
time (at a cold night, just before daybreak). I also noticed on the
radar that the shallow low seemed to be winding itself just to the
west of London - prolonging the precipitation.

My last question is why did we have to wait until April 6th for the
first proper snow of the winter (in London)? - though there was
appreciable amounts of snow I'm sure there was enough energy from the
sun through the clouds to effect a thaw - something which would not
have happened in January...