Steve Wood wrote:


I was out in the countryside from dawn this morning. As we under a big
high pressure area, there was mist in the valleys that had formed
overnight as air in contact with a cooling surface flowed downhill and
it's water vapour turned to droplets. All straight out of a text book.
What I do not understand is why cloud formed as the sun came up and soon
blocked out the sun.

So my question - how does cloud (not ground level mist) form in sinking
air?

Low-level turbulent mixing caused by convection underneath the subsidence
inversion is likely to be the main cause. When the cloud tops reach the
inversion they spread out resulting in a layer of stratocumulus.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.