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From: drw@cullvax.UUCP (Dale Worley)
Newsgroups: sci.misc,sci.physics
Subject: Question about relative humidity:  Why is it not always 100%?
Message-ID: <1507@cullvax.UUCP>
Date: Sun, 30-Aug-87 11:20:35 EDT
Article-I.D.: cullvax.1507
Posted: Sun Aug 30 11:20:35 1987
Date-Received: Fri, 4-Sep-87 02:42:35 EDT
Organization: Cullinet Software, Westwood, MA, USA
Lines: 19
Xref: mnetor sci.misc:471 sci.physics:2117

young@hoqax.UUCP (HUH) writes:
> My question is, why is the relative humidity not always 100%?
> 
> Shouldn't the liquid water on the surface of the earth (which there seems to be
> a plenty of) evaporate into the atmosphere and eventually reach an equilibrium,
> thereby making the actual pressure of water vapor equal to the vapor pressure of
> water?

You are completely correct, except for the fact that the Earth's
atmosphere is not in equilibrium.  It is a monstrous heat engine
driven by solar radiation.  If the Sun went out, not only would the
R.H. go to 100%, but all the winds would stop, etc.

Dale
-- 
Dale Worley    Cullinet Software      ARPA: cullvax!drw@eddie.mit.edu
UUCP: ...!seismo!harvard!mit-eddie!cullvax!drw
Apollo was the doorway to the stars - next time we should open it.
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