Message-Id: <v01540b13b0daf982dbbf@[192.174.2.173]>
Date: Thu, 8 Jan 1998 13:50:07 -0800
To: pinhole@exploratorium.edu
From: pauld@exploratorium.edu (Paul Doherty)
Subject: Re: wave reflection
Re U-V and glass
"It's more complicated than that"
Glass does absorb U-V
however the absorption is a finction of frequency.
Ultraviolet is divided into three ranges
U-Va is nearest to visible light
U-Vb is higher ferquency
and U-V c is higher still, U-Vc is totally absorbed by air and so does not
penetrate the earth's atmosphere.
"U-V b" radiation is greatly absorbed by glass, however "U-V a" is not
blocked much at all at the blue end and blocked a lot at the U-Vb end of
its spectrum.
U-Va can cause reddening of the skin and enough can cause sunburn, however
it is not as effective at producing sunburn as U-V b.
Paul Doherty