Here’s a hypothetical:
Let’s imagine that we have an atmosphere of two parts. The first 10 km of the atmosphere has no greenhouse gas. The second 40 km has a greenhouse gas incorporated.
In the lower layer there is water vapor and clouds that come and go according to the temperature of the air.
Let’s consider that there is an impermeable membrane over the surface preventing the interchange of moisture with the atmosphere. No precipitation of moisture from the atmosphere falls to the surface.
Now, set this planet spinning in space around a sun in such a way that the polar sections experienced permanent night for part of the year so that the entire depth of the atmosphere (both layers) within the polar night region cool down and a gradient of ever diminishing temperature occurs all the way from the surface to the top of the atmosphere, the entire 50 kilometers.
Parts of the planet would be warm and parts would be cold. Ascent and descent of the atmosphere is forced by these thermal differences but the ascent is usually confined to just a few kilometers in elevation.
That greenhouse gas absorbs long wave radiation from the planet. This sets up a convective circulation within the polar night that spins the greenhouse gas rich air away from the pole towards the margins of the polar night. Remember that temperature descends all the way from the bottom to the top of the atmosphere within the polar night and this promotes convection throughout the entire profile. In fact the two layers act as a coupled circulation.
So, greenhouse gas descends into the near surface layer on the margins of the polar night that hitherto was entirely free of greenhouse gas. This causes the air on the margins of the polar night to warm as it descends. Surface pressure falls away in this region.
Now, if this circulation came and went, we would see clouds come and go on the margins of the polar night as the air alternatively cooled and warmed.
Now, let us imagine that there is a wind that blows from the polar night towards the equator that carries greenhouse gas towards the equator warming the air and causing cloud to disappear.
Now, let us introduce land and sea in the winter hemisphere and assume that the air on the margins of the polar night descends preferentially over the sea. We would then expect the greenhouse gas to be concentrated in the atmosphere over the sea. This would give rise to a pattern of warm and cool air, clouds in the cool zone and none in the warm zone. A cloud free path would be set up that ran from the warmer margins of the night zone towards the equator. The cloud would come and go as the circulation waxed and waned.
The lower of the two layers would show zones of warmed air like the map below.
And under the influence of the wind that blows towards the equator we might see a pattern of sea surface temperature like this:
Now, let’s imagine that there is an insidious chemical generated in the rarefied atmosphere above both layers that has an affinity for the greenhouse gas and this chemical is intermittently trickled into the top of the layer containing the greenhouse gas. Accordingly, the greenhouse gas content of the night zone would wax and wane causing a fluctuation in cloud and the temperature of the sea.
If we wished to know what was changing the weather and the climate we would have to look at what changes the trickle rate and what causes the polar circulation to wax and wane.
We look closely and find there is a ‘night jet’ injecting that insidious chemical into the top of the greenhouse gas containing layer. It is active when surface pressure is high.
We discover that the pressure is high when the sun is less active.
When the sun is active pressure is low and the night jet is less active, the greenhouse gas content builds up, the temperature of the column increases and the convective circulation goes into overdrive.
And the temperature of the polar stratosphere might look like this:
So, in this circumstance the clouds disappear and the planet warms. Does anyone recognize the origin of the great Pacific Climate Shift of 1976-8?