On Sun, 29 Apr 2007 12:33:20 GMT, Citizen Bob wrote in


Clouds absorb and re-radiate downwards the upwelling long-wave radiation
from the surface. When cloud cover replaces clear sky the surface radiation
continues, but can no longer escape to space. The air temperature near the
surface rises towards the ground temperature until a new balance is
achieved.

But how can that cause a temperature rise?

Soil heat flux, as explained by Bernard, is still happening and in an
upward direction. If there was equilibrium *before* the cloud (i.e. upward
soil heat flux approx = net outgoing long wave radiation), the arrival of
cloud will reduce the loss of energy from the soil, yet the same heat is
arriving from below, so the surface warms, until a new equilibrium
temperature is reached.

--
Mike Tullett - Coleraine 55.13°N 6.69°W posted 29/04/2007 19:50:55 GMT