On Thu, 24 Jul 2014 17:01:11 +0100, Hugh Newbury
wrote:

Early this morning (0450) the humidity recorded by my AWS was 3%, the DP
-29.6.

I suppose everyone's figures were similar? So what caused this surely
exceptionally low figure? Simply the Spanish or Saharan plume?

I think your instrument recording DP failed, or it transmitted/you
recieved an incorrect value. At 04:50 BST here, air temp was 18.0 deg
C, dew point +14.2 deg C, humidity 78%.

This afternooon I did record my lowest humidity of the year so far,
when the air temp. was 29.6 deg C, dewpoint 11.2 deg C, relative
humidity 32%.

--
Dave
Fareham (W)