Frost calculations

[JHellis]

Hi

is there a formula that can be used to calculate if there was a frost overnight> 

John

[d_l]

It isn't really a fully developed algorithm, but I'm using the dew point of my ISS relative to the surface radiation temperature of my leaf wetness sensor to predict if there has been frost on hard, dry surfaces.  If the dew point exceeds the radiation temperature as shown on WL plots, then there is generally frost.  Especially if the RH is at or above 90%. If the RH is only about 85% or below, the frost is light or iffy.  The RH cut offs are still under development.

This method doesn't really predict frost on the grass because the microclimate (dew point) is apparently much different over it than where my ISS is located.