In message , Martin Rowley
writes

"Martin Rowley" m wrote
in message ...
Sunday, 07 August 2005
BRACKNELL (TF)
other data: With a day max of 22 (rounded), an air-mass dew point of
around 5, not much cloud and a failing wind, it is going to be
interesting to see what the air (and grass) min is going to be; we'll
probably keep a very gentle northerly through the night, so using
McKenzie, (22+5)/2 = 13 [rounded] with 5 kn and 2 oktas cloud gives
a K value of 5 or 6, so theoretical min around 7 or 8. The strong
solar heating of the ground etc., though will play a part in
offsetting the fall of temperature. ]=

... 8.6 in the end (air min); not too bad considering I was using the
'general' K values rather than specific ones for this site.

Martin.

For Chalfont St Giles using "general" K values I would have arrived at a
predicted min of 6. The actual min turned out to be 7.0 so a very
similar performance to what you had, Martin. Not at all bad.

Norman.
(delete "thisbit" twice to e-mail)
--
Norman Lynagh Weather Consultancy
Chalfont St Giles 85m a.s.l.
England