From: blockedofcourse@foo.invalid   
      
   On 11/18/2025 2:39 AM, Liz Tuddenham wrote:   
   > Don Y  wrote:   
   >   
   >> Particularly, cloud cover.   
   >>   
   >> How can I quantify the extent and "density" (opacity) of cloud   
   >> cover?   
   >>   
   >> And, to make it even more interesting, doing so AT NIGHT, as well?   
   >   
   >   
   > At night the clouds would appear warmer than space, so an infra-red   
   > scanning system would give you a picture of the clouds.  I don't know   
   > how you would calibrate it, because the apparent cloud temperature would   
   > depend on air temperature and IR radiation from the earth.   
      
   But the cloud cover wouldn't instantaneously change from observations   
   made during the preceding daylight/twilight periods.  I.e., "THIS is   
   what cloud cover looks like and THAT is what clear skies look like,   
   in the Ir" (assuming both are present)   
      
   Think about how "you" can tell the condition of the skies without   
   even looking upward:  "It's not *bright* enough for 1PM" or "The light   
   is the wrong 'color'"...   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)