RE: ATM Ambient temperature drop question

["Matt Luttinen" <mluttinen@qwest.net>]

Ed,

Seasonal information should be available from your local weather
service and is probably online. However, you may need to take
measurements
yourself and build up a database for your particular viewing site(s).
Here
in Arizona the temperature delta per hour would vary wildly depending 
on the site (our club has several ranging all over the state, some
desert,
some in the mountains) and the time of year. I am building my scope
with the hot summer in mind and fans galore to cool my glass . . .

I am also going to get a good thermometer and start building a
temperature
database . . .

Adler calls 2 degrees/hour "typical" but your situation might be
different. If
you think it is worse, then fan cooling becomes even more important. He 
states that ~1.5 degree/hour is the point at which cooling becomes
necessary.

Regards,

Matt Luttinen
Saguaro Astronomy Club
Glendale Arizona
33:33:58 N, 112:09:54 W