On 13 Feb, 16:38, "Dave Cornwell"
wrote:
Just when I thought I'd mastered some of the maths involved in the
relationship between things like 850hPa and max temp etc today seems to have
thrown quite a big spanner in *the works. At 2pm temp was 4.6C under full
cloud. There was some light rain about. According to the GFS hires the 850
hPA was -11C at that time for this location. I realise the lower atmosphere
is a 3D model but this does seem to be a bit extreme with no solar heating.
I have to presume that the slack NE flow is producing an unmixed layer very
close to the surface which is then giving a temperature reflective of the
current temperature of the North Sea rather than the air aloft which would
normally be used for a max temp calculation. This would also explain the
colder temperatures further west despite the higher 850 hPa's.

Dave,
S.Essex

Could also be that the air is dry? i.e. perhaps a higher lapse rate
for at least part of the ascent? Dry air lapse rate is 1C per
100metres, so in theory you could get a 15c differences between sea
level and 1500metres.