Ticker for August 2, 2004

                
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August 2, 2004     August 2, 2004     August 2, 2004     August 2, 2004



It's Not The Heat, It's the Rate of Heat Transfer

Summer, obviously embarrassed by its all-too-early May arrival, went
into hiding for two months before returning - with a vengeance.
Yes, our old friend has returned, heralded by soaring temperatures
and replete with many former residents of the Gulf of Mexico (also
known as "water molecules").

One of the indicators of summer's reign is the heat index, which
is certainly evident today:




As most folks know, the heat index is associated with temperature
and relative humidity.  However, the phrase "feels like" also gets
thrown around with the heat index, which is something of a
linguistic disservice inflicted by the weather community.
The heat index is a measure of physiological processes - an
indicator of how hard you body will work to cool itself.

Your body knows of one cooling method: perspiration.  On a relatively
dry day, your sweat can evaporate more readily than on a humid day.
Evaporation is a cooling process, so the rate of cooling is
determined by the rate of evaporation - which is subtly yet
monumentally different than the rate of evaporation.

When the evaporation rate is held in check by an abundance of water
molcules in the atmosphere, your body responds by increasing the
perspiration rate ... with little or no effect on the evaporation
rate.  Unfortunately, we're programmed to continue to ramp the
perspiration no matter how fruitless it may be.  The end result:
dehydration, cramping, heat stress, or heat stroke.

Now, don't get us wrong.  A heat index of 103F certainly "feels"
worse than a heat index of 87F.  But using the words "feels like"
in association with heat index might imply that toughness is all
you need to get through the day.  That's not the case!  The best way
to get through the day is to avoid the heat or drink lots of
non-caffeinated fluids!  In fact, a "toughness" or physical
tolerance for discomfort may work in your disfavor on a day like
today!