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From: peterb@pbear.UUCP
Newsgroups: net.astro
Subject: Re: StarDate: July 11 Wind
Message-ID: <700001@pbear.UUCP>
Date: Tue, 16-Jul-85 17:25:00 EDT
Article-I.D.: pbear.700001
Posted: Tue Jul 16 17:25:00 1985
Date-Received: Thu, 18-Jul-85 06:58:00 EDT
References: <333@utastro.UUCP>
Lines: 28
Nf-ID: #R:utastro:-33300:pbear:700001:000:1275
Nf-From: pbear!peterb    Jul 16 17:25:00 1985


>>
>> On our planet Earth, the wind is always blowing somewhere.  So the wind
>> must ve a constantly renewable source of energy.  It turns out that the
>> wind stems from the ultimate energy source of almost everything on
>> Earth -- the sun.
>>
>
>  Which is puzzling:  since the air is heated in the morning, and
>cools in the evening, why isn't there a constant wind (shock wave,
>actually) at the speed of the earth's rotation?
>/* Written 11:52 am  Jul 11, 1985 by lanl!lhl in pbear:net.astro */

At sunrise the sun has to pass through a thicker layer of air to heat it
since the atmosphere is thickest(in relation to the sun's direction) when
the sun is on the horizon. So the amount of energy is spread over a larger
amount of air. As the earth rotates, the air layer thins, and the amount of
energy per unit air volume increases. After the sun passes through the 12
O'clock position, the air layer thickens, and the energy per unit volume
decreases.

Since the energy function is smooth (except at sunset/sunrise, and there the
discontinuity is low), a shock wave would be quite small, if noticable at
all. Also with the mass of the air itself, the shock wave would be absorbed
by the nearby air particles.

Peter Barada
{ihnp4!inmet|{harvard|cca}!ima}!pbear!peterb