writes:

You really should read the textbooks.

I have.

Try this website:
http://www.islandnet.com/~see/weathe...nts/frost1.htm

I quote from this article from the above site:

The above site is not a textbook.

"Frost forms first on rock, glass, or metal surfaces that lose heat
more rapidly through radiative cooling than the surrounding air. This
is why car windshields frost over before frost forms on surrounding
vegetation. If the surface on which it forms has a temperature below
the frost point, frost may even appear when the officially reported air
temperature is above freezing."

Surfaces such as metal and glass cool more during the night because of
radiative cooling. However, they emit in the infrared, and water
vapor, CO2, and other gases in the atmosphere absorb it, so it doesn't
get very far.

Early in the morning, as temperatures rise, the air may be filled with
moisture but slightly warmer than surfaces that have cooled greatly
during the night and conduct heat well (such as metal). The moisture
in the air may condense (and even freeze) on such surfaces. But there
isn't much radiation loss at ground level unless the air temperature
is lower than surface temperatures. Remember that not only does the
atmosphere absorb infrared, but it also emits it.

The aviation weather textbooks teach the same thing. Another website,
this time by NASA:

http://aircrafticing.grc.nasa.gov/co...4_2_1a_RI.html

This site requires Flash, so I can't read it.

Now try to tell people the dry surface temp won't drop below the
air temp.

I already have.

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