On 20/06/2018 20:21, Gary Harnagel wrote:
On Wednesday, June 20, 2018 at 5:39:43 AM UTC-6, Paul Schlyter wrote:
In article ,
says...

On Friday, June 8, 2018 at 5:06:00 AM UTC-6, Paul Schlyter wrote:


The effect of cloud cover for the local albedo, reducing incoming light
and heat from the Sun to the ground, will be just as instantaneous as
its effect of reducing heat flux from below into space.

But clouds reduce the heat flux coming up from the surface.

No, they don't. But the clouds do radiate IR radiation back to the
ground. And since the clouds are cooler than the ground, the clouds also
reduce IR radiation out into space. Maybe that's what you meant.

I'm talking about the NET effect. Clouds reduce the amount of heat escaping
into space, but they also reduce the amount of solar energy coming in.

The net effect depends both on the height and *type* of the cloud.

High cirrus is optically thin, cold and lets in plenty of solar energy
but is dense to outgoing thermal radiation and have a net warming effect.

Low optically dense clouds reflect a high proportion of incoming solar
radiation are warm and have a slight net cooling effect - although their
main effect is to significantly reduce diurnal temperature variation.

Deep convective clouds tend to be just about neutral for energy balance.
See:

http://nenes.eas.gatech.edu/Cloud/NASAClouds.pdf

For a reasonably accessible review.

--
Regards,
Martin Brown