[ATM] thermal issues

[Peter Abrahams]

> remember that for roughly every 1C of difference between the mirror and 
> ambient temperature you will have 0.3 to 0.5 arc second degradation of 
> image quality.  
> Shane Santi 

I'm not sure if this was meant as an informal rough guide to what you might see in an eyepiece, or if the precision in 
these numbers reflects some measurements or publications.  So I don't want to make too big a deal out of this.  But... 
where can someone learn more about this?  You are referring to the optical effects of the thin layer of air just in 
front of the mirror?
thanks
Peter