Endurance.Net Ridecamp Archives

Absolutely correct. The only way evaporative cooling can work is when the
air can absorb additional water vapor. When the humidity is high the air
is already close to saturation and will not absorb additional water. When
the humidity is low and it can.  The water takes heat from the skin to go
from the liquid form to go the vapor form and absorbed by the air. Each gram
of water will carry off so many calories of heat ( latent heat of evaporation).

This works fine in dry climates but not in more humid climates. Swamp coolers
work fine in the SW but they sure don't work in the east. 

Many times in the east the only way I have found to get cool is stick my
head into a cooler full of ice. Of course you have to drink the beer to make
room:-).

Truman

Glenda R. Snodgrass wrote:
> > the helmet.  The air flowing through your helmet evaporates the water and
> > cools the head.  A soaked scarf lasts about 3 hours on a hot day; maybe a
> > head "cookie" would last a similar amount of time.
> >   
>
> There is no evaporation when you are in high humidity, which is the
> biggest problem.  In fact, putting water on and leaving it on during high
> humidity can exacerbate the problem, as the water absorbs the warmth from
> sunlight and actually insulates the skin, causing higher temperatures
> rather than cooler.  
>
> Water only helps in hot humid conditions when it is either (1) cold and/or
> (2) poured on and scraped off quickly.  A wet scarf around the neck is
> *miserable* in humid weather, except for the first 5 minutes after it
> comes out of the icechest.