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RE: [at-l] I'm confused



You are not confused. I didn't check the persons math that gave you the new
conversion factor between Joules per square meter, and milliwatt seconds per
square centimeter, but I'm sure they are right. The other figure you had was
completely wrong. Think about it this way ... we are simply converting SI
units which are all related to each other by factors of 10.

For example:
1m = 100cm
1W = 1000mW
1W = 1J /s

So you see there is no way to get a conversion factor of 16.8 or whatever
the number was that you had before.

Jim McBride



> ----------
> From: 	David  F. Addleton[SMTP:dfa@wimlaw.com]
> Sent: 	Tuesday, August 03, 1999 11:07 AM
> To: 	at-l@backcountry.net; Pete J. Osler
> Subject: 	Re: [at-l] I'm confused
> 
> I must be the confused one.
> I just accepted the conversion given me from elsewhere.
> At any rate, your figures are better than the ones I used for this issue
> since they increase the sun's dose of UV-A and UV-B in my calculations:
> 
> J/M^2	mw-s/cm^2 	dose @ 1 minute	
> 800	80		4800
> 1000	100		6000
> 2000	200		12000
> 3000	300		18000
> 4000	400		24000
> 5000	500		48000
> 
> instead of 
> 
> J/m2	mw-s/cm2	
> 800	1.3344	
> 1000	1.668	
> 2000	3.336	
> 3000	5.004	
> 4000	6.672	
> 5000	8.34	
> 
> The result is to diminish the time necessary for the sun to do its
> sterilizing work, using UV-A and -B. It likewise increases the miniscule
> amount of UV-C that reaches the ground, esp in high altitudes by the same
> amount:
> nearly 60 times greater than I had calculated.
> 
> ----------
> > From: Pete J. Osler <osler@btv.ibm.com>
> > To: at-l@backcountry.net
> > Subject: [at-l] I'm confused
> > Date: Tuesday, August 03, 1999 7:35 AM
> > 
> > > 1 joule/square meter = 16.68 mw-s/10,000 sq cm  =  .001668 mw-s/sq cm
> >  
> > If I remember my high-school physics:
> > 
> > 1 Watt is defined as 1 Joule / Sec, or conversely 1 Watt-Sec = 1 Joule
> > 
> > 1000 mWatt-Sec = 1 Watt-Sec = 1 Joule
> > 
> > 1 Joule / M^2 = 1 Watt-Sec / M^2 = 1000 mWatt-Sec / M^2 ( where '^2'
> means 'squared' )
> > 
> > 10000 cM^2 = 1 M^2. ( where '^2' means 'squared' )
> > 
> > 1 Joule / M^2 = 1000 mWatt-Sec / 10000 cM^2 = 0.1 mWatt-Sec / cM^2 
> > 
> > ...Pete Osler Ga->Me '81
> > * From the Appalachian Trail Mailing List |  http://www.backcountry.net
> *
> * From the Appalachian Trail Mailing List |  http://www.backcountry.net  *
> 
* From the Appalachian Trail Mailing List |  http://www.backcountry.net  *

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