"ronaldbutton" wrote in message
...
snip
At present in my back garden the temp is 26C and the RH 55%,which
with the easterly breeze feels very comfortable ,so excuse my
ignorance but how the comfort levels determined viz a viz
temperature combined with humidity ?.
I'd hate to enjoy myself whilst so many people seem to be struggling
with the dreadful heat and having to remove their anoraks.

.... well, I'm probably way out of date now on all this as I know that
a lot of work has been done in the Met Office with the DoH &
individual NHS trusts. However, the standard algorithm we used to use
to work out a 'temperature-humidity' index is as follows:-

THI = 0.4 (T + W) + 4.8 .... (for degC).

whe
THI 'Temperature/Humidity Index'
T = Dry bulb (screen) temperature
W = Wet bulb (screen) temperature

For THI 20, " increasing discomfort felt" [ for ' sedentary workers
indoors ' or outside in shade in light winds ]
THI = 24 .. half sample population will feel 'discomfort'.
THI 27 .. 'all' are likely to be distressed.

From your figures, I make your THI somewhere around 23.

As I say, things have no doubt moved on, but it should give a
reasonable guide.

The Met Office system here ...
http://www.metoffice.gov.uk/weather/...lth/index.html

appears only to be triggered by temperature, though given that night
minima are included (which in turn are governed by boundary-layer
humidity), you could argue that the humidity element is implicitly
covered. I believe though that in the US humidity is explicitly
modelled in heat-stress warnings.


Martin.

--
Martin Rowley
West Moors, East Dorset (UK): 17m (56ft) amsl
Lat: 50.82N Long: 01.88W
NGR: SU 082 023