RE: [ATM] asymptote to ambient

[Mark Holm <mdholm@telerama.com>]

Donald Good wrote:


>I read in a recent review of dew heaters that a mirror can drop below
>ambient by radiative cooling.
>
Yes, and with today's much more open designs, the mirror is more open to 
the sky, thus will cool more by radiative cooling.

This is also another argument for fans.  When radiative cooling is 
significant, a fan will actually help keep the mirror warmer.  If you 
happen to be in a locale where air temperature does not often drop below 
dew point, but a radiatively cooled surface might, then a fan might be 
all the extra edge you need to keep away dew.

-- 
Mark Holm
mdholm@telerama.com


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