Dave Liquorice wrote:

On Sun, 8 Jun 2008 19:30:06 +0100, Mike Tullett wrote:

Mike - you are quite right to question the times of 16.00 to 19.00.
Solar radiation, of any kind, will peak an hour or so either side of
local noon.

Ish. Cloud cover will make a difference Thick heavy cloud and midday v
clear skies late afternoon... But cloud can probably increase the UV level
as well, high thin sirrusy stuff producing more back scatter?

Cumulus clouds are more likely to produce an increase due to reflection. I
vaguely recall that they can increase the level by as much as 100%.


This would not account for "a UV index and this always peaks between 16.00
and 19.00" though.



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