Humidity

Really. I hadn' t noticed it being that bad.

I think that is broadly correct. 100% is all teh water vapour the air will support and after that it rains.

If it doesn't, get your money back,

My local airbase sez

Wind 10 mph from the South/Southwest Temperature 23°C Humidity 65%

Downstairs is at a pleasant 23°C and upstairs at 25°C at the mo.

Which is perfect AFAIAC

I think there's a kind of saturation point at which the air is holding all the water it can hold. That would be 100%.

aiui it's important because at high humidities your sweat doesn't evaporate, so you feel pretty uncomfortably hot and sweaty, and in extreme cases you overheat, die even.

TW

Weather reports and forecasts use relative humidity: how much water vapour is in the air as a percentage of the maximum that the air can hold at the current temperature and pressure.

When the relative humidity hits 100% (possibly by cooling the air down) water condenses on solids.

The Natural Philosopher snipped-for-privacy@invalid.invalid wrote

Not necessarily rains, often just fog

Don’t know what the actual humidity figure was here but I live roughly

GH

I think that moist air holds more heat and prevents effective perspiration, a double whammy.

I have experioenced 35°C @ 100% humidity (Chichen Itza) and 50°C @ 15% humidity (Death Valley locality)

Given enough to drink, I'll pick Death Valley any day

Its usn't a question of 'holding heat' its the ability to pespire that matters

The moisture in the air holds the heat.

So do the molecules of oxygen and nitrogen.

I take it you have no education in science?

From memory no subject was called science, we had chemistry and physics.

Not sure why you have a problem with the moisture holding heat if gas molecules can hold it.

But that’s not what you said…

If you drafted a scientific paper intended for publication in a journal, the reviewer would put a big ring around the sentence ”The moisture in the air holds the heat” because as it stands, the wording excludes any other component from holding heat in the system under consideration. It needs a qualifier such as ’some of’ or ’most of ’, depending on the thrust of your research.

And indeed 'holding heat' is not a very scientific term.

And in any case has little to do with the ability to lose heat. Which is all about perspiration in the human case, and not about conduction.

Ice is very good at 'holding heat' too.

Losing heat is about how fast you can lower the surface temperature of the body, and in still air that is how fast evaporation takes place. Period. Winds in drier air move the evaporated water vapour away allowing better perspiration loss, but if the air is already saturated wind does not help.

In extremely dry conditions it doesn't help either, because if the air temperature is above body temperature what you want is to create a local cool spot through evaporation and not have it replaced with warmer air immediately.

Hence use of e.g djellaba in hot desert conditions.

Rubbish :-)

Indeed. That's what we thought originally.

I doubt there was much thought, if molecules can hold warmth then clearly so can air, unless you think it consists of anything other than molecules?

But in writing that water vapour holds the heat, without any form of qualification, you are putting forward something that isn’t factually correct. It doesn’t matter what you think others should know about the issue, it’s up to you to be precise in your description.

To be clear I said "I think that moist air holds more heat and prevents effective perspiration, a double whammy."

If you want to interpret it in any way other than what it says be my guest :-)

To a first approximation I doubt if moist air holds more heat because whatever the proportion of water molecules the total number of particles in a given volume of gas at a particular T&P should be the same.

It was my view, not a scientific explanation, as my wording clearly shows.