writes:
On a clear night the skin temperature can go BELOW the air
temperature due to the radiation losses into space.


Tony wrote:
Dan, it's not an important point, but from the physics/theromdynamics
side of the issue, the top surface of the wing is really at risk of
radiational cooling. The wing's leading edge's shape would allow
convective warming, as the warmer air in contact with the surface would
cool and flow downward.

And that's where we see frost forming: on top of the wings,
fuselage and stabilizer.


Mxmanic wrote:
The temperature of the aircraft won't drop below the temperature of
the ambient air, as long as the aircraft is dry.

You really should read the textbooks. Try this website:
http://www.islandnet.com/~see/weathe...nts/frost1.htm

I quote from this article from the above site:

"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."

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

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

Dan