Originally posted by Anna
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Nobody has come back after my last message to say, hey, what about all that dull weather we got with a south-east wind behind an anticyclone during the last winter then? And of course I omitted to mention that my explanation was mainly referring to how highs behave in the summer half of the year at our latitude. Anticyclones tend to be cloudier in winter by virtue of the amount of fog that forms at night over land within their calm, slow-descending airmasses, and that as the dewpoint rises with the rise in the daytime temperature this fog rises into stratus cloud which, being trapped beneath the inversion, has nowhere to go. Sunlight being so weak, it cannot penetrate this layer, which therefore persists unless a) air invades the system from drier regions or b) the high moves away and the fog/stratus in broken up and/or blown away by stronger winds coming in.
Anyway, it seems my predictions have more-or-less come true for this weekend, although here there have been quite large amounts of stratocumulus coming in from the cold North Sea, and air temperatures in this part of S London didn't exceed 13 C today. But that's 1 degree C above what's to be expecgted for early April, so one shouldn't complain!
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