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From: cramer@kontron.UUCP (Clayton Cramer)
Newsgroups: net.physics
Subject: Re: Haze
Message-ID: <498@kontron.UUCP>
Date: Mon, 27-Jan-86 19:11:36 EST
Article-I.D.: kontron.498
Posted: Mon Jan 27 19:11:36 1986
Date-Received: Thu, 30-Jan-86 02:17:28 EST
References: <318@epicen.UUCP>
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Organization: Kontron Electronics, Irvine, CA
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> I'm a little confused about haze.  My question is this:  What, exactly,
> is haze, and why is it so common.  I'm talking about the natural, non-
> pollution related haze that is often in the air.  I'm not talking about
> fog or clouds, which I know are composed of water droplets that have
> condensed in air that has become super-saturated with water by the
> cooling of moist air.
> 
> My guess would be that haze is composed of microscopic water particles,
> much smaller than those in fog.  I can see that these could exist in air
> that is close to 100% relative humidity, but wouldn't they quickly
> evaporate if the air was any dryer?  I'm sure that it is not this humid
> most of the time that I see haze in the air.  Haze often persists on
> especially warm days, when surely the warming of the air drives the
> relative humidity down.
> 
> Can anyone clear this mystery up for me?
> 
> 		Kreg Martin

Part of what makes the Great Smoky Mountains in the East so hazy is
the presence of xylenes, a class of hydrocarbons produced by trees and
shrubs.  One of the reasons that most of the densely populated sections
of California now have vapor-recovery nozzles on the gas pumps to prevent
hydrocarbon emissions.  When the issue first came up, the Ventura County
Air Quality Management District resisted the nozzles because 75% of the
hydrocarbon emissions came from trees and shrubs.  (This is the origin
of the garbled statistic that Reagan used several years ago.  You will
also recall the Democrats ragged him unmercifully for it -- after all,
they knew that NOTHING bad could come from Mother Nature).