From: blockedofcourse@foo.invalid   
      
   >> Do I need that much more "resolution" than simply imaging (sky and soil)   
   with   
   >> an Ir camera?   
   >   
   > The idea is to have a two pixel imaging system consisting of a pair of   
   > thermometers with low thermal inertia one facing upwards shielded from the   
   > ground and another that is ground facing and shielded from the sky.   
      
   The thinking being that "change" is quick and sudden?   
      
   > The temperature difference and its rate of change gives you the extent to   
   which   
   > the situation is likely to allow a frost and/of fog to form.   
   >   
   > You also need windspeed and relative humidity. This is probably the simplest   
   > kit configuration to predict risk of frost of fog.   
   >   
   > Dew point was always very important to astronomers and highway traffic   
   monitors   
   > so you can get purpose built kit for this sort of thing.   
      
   We used to used chilled mirror sensors for dewpoint.  But, were concerned about   
   *actual* dewpoints as we were regulating a thermodynamic process.   
      
   I think I can cut corners, here, as I am looking for "correlations" and not   
   "numerics":   
      
   "When I see this set of conditions, the following has proven to be true..."   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)