"Alastair B. McDonald" wrote in message
...
The following question has just been asked in the RealClimate blog:
"Frost question.

Night starts out cloudless; ground cools; it gets cold enough; frost forms;
early in the morning, still well before sunup, a bank of clouds appears.

Can the frost melt before solar hits it?"

I wonder what the answer should be; perhaps not just yes or no.

Yes. It of course depends on the height of the cloud, but if it is a bank of
low cloud, and not too thin, then yes. Cloud blocks heat from the earth's
surface from radiating to space, and absorbs the long-wave radiation from
the surface and re-radiates some of it back to the surface.
There is a good example this evening with patchy cloud.
Look at this net radiation graph from Reading Uni:

http://www.met.reading.ac.uk/weather..._graphs.html#7


--
Bernard Burton
Weather data and satellite images at:
www.woksat.info/wwp.html