The flip side is that UV induced clouds will be diffuse and uniform and diffuse clouds are more cooling than concentrated ones. Also they may tend to reduce concentrated convection which is cooling (because it allows more IR to escape between clouds). From that standpoint, UV would be warming, not cooling.
So what's the bottom line? Beats me, but a decent model should be able to figure it out.
UV can only form clouds during daytime
High level ice clouds which would be one of the primary results of UV interations are persistent through the night and hold atmospheric LW radiation in much as a blanket works.
I would also suspect those are high clouds, therefore cooling.
You have it just backwards, high clouds, on balance, warm by absorption & re-emission of LW radiation back into the atmosphere thus acting as a blanket. The case of the partially reflecting mirror of the high CO2 cloud and the Venus high level sulfate clouds being examples of the extreme case of the class.
Mid level clouds tend to be balanced reflection vs absorption/re-emission neither warming or cooling.
Low clouds tend to cool on net, by reflection of visible wavelengthw and absorption/reemissions of LW back up towards space.
The flip side is that UV induced clouds will be diffuse and uniform and diffuse clouds are more cooling than concentrated ones.
Sorry that one is just flat invalid, diffusion tends to increase the pathlength LW radiation must follow to find its way out of the atmosphere thus acting to warm more than cool. The dispersal off the direct vertical tends to trap radiation in the atmosphere by raising refractive effects as well as longer path through the atmosphere assuring any LW is more efficiently captured.
So what's the bottom line? Beats me, but a decent model should be able to figure it out.
Ahmmm, there is no such animal as a decent model for clouds. Which, along with spatial resolution, is one of the greatest factors for error in current climate models.
"UV can only form clouds during daytime, therefore cooling."
Oh, so the cloud formation (caused in part by added UV) just goes away at night? No. It doesn't. And, unless it rains the concentrated holding of water vapor contributes to warming.
"The flip side is that UV induced clouds will be diffuse and uniform and diffuse clouds are more cooling than concentrated ones."
Spoeculation, not science. In fact, the scientific investigation of UV's assist in cloud formation is not cloud-specific, nor does it find that assistance to be cloud-specific for only certain types of clouds.
"Models" are only theories and so far, in climate science are less reliable than scientific inferences from real data alone and only real data and only after that data can establish true mechanisms and not the guesswork found in most ICCP models.