On Wednesday, 27 May 2020 10:38:20 UTC+1, Norman Lynagh wrote:
Graham Easterling wrote:


I agree with most of what you state about factors that affect UV
levels except humidity. I do not think it affects them.

Nicholas
Meir Heath, Stoke-On-Trent 250 metres above sea level.

Equally, I am sure it does. If Norman reads this I know he'll agree.
In fact, anyone that spends a lot of time outdoors, certainly on the
coast of SW England where high humidity is common, fully appreciates
the fact.

How else do you explain the big drop in UV when a cold front goes
through? Certainly lower high level ozone sometimes being associated
with a warm sector ridge is partly the cause, but the whole thing?
If you don't except it's the humidity, despite the evidence, you need
to come up with an alternative explanation why it's so high in air
which has none of the clarity of that behind the cold front.

Somewhere I'v got a list of times when the Camborne UV has hit 9,
never in clear, clean sunny mP conditions.

Graham
Penzance

I can't comment on actual UV measurements but, from personal
experience, for any given temperature I find that I burn more readily
in high humidity conditions than in dry conditions. In coastal, fairly
humid conditions, in this country with the temp in the low 20s I burn
much more than I do in 40° in very low humidity in inland Australia.
Indeed, I have to be very careful in this country on summer days when
there is a complete cover of low cloud but nothing above it. On such
days, if unprotected, I would burn very badly.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
https://peakdistrictweather.org
twitter: @TideswellWeathr

Where in inland Australia are you referring to? The temperature is not linked to UV levels. It is about how high the sun is in the sky and the latitude. Lower latitudes will have higher UV levels than higher latitudes.

Nicholas
Meir Heath, Stoke-On-Trent 250 metres above sea level.