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Re: What is an "active ectotherm"?

At 04:03 PM 10/10/96 -0500, Mickey P. Rowe wrote:

>Think of an animal as a little furnace which burns sugars, fats and
>sometimes proteins.  The temperature of the animal is going to depend
>on the rate at which heat is produced by the burning and the rate at
>which heat is being lost to the environment.  The animal's temperature
>is stable when these two rates are equal.  The driving "force" which
>determines how rapidly heat is lost to the environment is the
>temperature difference between the animal and it's surroundings, but
>the rate of heat transfer is also proportional to how well the
>surroundings can take the heat away.  We stay warmer in air of a given
>temperature than we would in water because the water takes heat away
>better than air.  That means that a smaller temperature difference is
>required between you and the water in order to get the same heat
>transfer that you would get between you and the air.

   An example that people might be familiar with is the wind chill factor.

   (As an aside, the next time you hear a weatherman use the following to
say that the temperature of moving air is the same as non-moving, don't
trust his weather forecast.  The temperature of air DOES go down when it
moves.  If anyone is interested in why, ask me in e-mail.)

   Heat transfer is dependent on the relative temperature AND the speed of
the air.  The wind chill factor calculates what the temperature would have
to be in no wind to produce the same kind of convective heat transfer you
get at the current wind speed and temperature.

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