On Thursday, 5 February 2015 13:23:20 UTC, wrote:
"Alan [Guildford]" wrote in message
...
On Thursday, 5 February 2015 12:35:48 UTC, wrote:
Having had a week of not so bitter weather with temps around 5C I was
expecting it to be colder today. So why, with 850 hPa indicating -8C
here, sub 528 dam, is it 6C and raining in the showers?

Dave, S.Essex

That is certainly possible with a dry adiabatic lapse rate and/or
instability at the surface.

Except it is not. The Ekofisk sounding in the North Sea is DALR up to 900
hPa only. The wet-bulb freezing level is at 300 metres asl, meaning snow
down to 100 metres asl unless heavy. The surface temperature over the sea at
Ekofisk was around 5C.

Will
--
http://www.lyneside.demon.co.uk/Hayt...antage_Pro.htm
Will Hand (Haytor, Devon, 1017 feet asl)
---------------------------------------------

So assuming the 850mb level is approx 1500 metres asl with a temperature of -8C, and the surface temperature is say +5C thus giving a difference of 13C, and a lapse rate of approx 0.85C / 100metres.

This is somewhere between the dry and saturated lapse rates so I was guessing with the dew point being around 0C [according to the GFS] that
at least some of the lapse rate would be at the dry end of the scale?