"Space weather" is actually a thing. It doesn't really have anything to do with clouds, though. Most of the influence on the extreme upper atmosphere comes from solar phenomena, and their interactions with the earth's magnetic field.

Solar flares and other similar events happen all the time. They're not really noticeable at ground level, because they don't appreciably affect the sun's visible brightness, and the density of matter involved is tiny compared to the atmosphere at ground level. But at the heights where satellites orbit -- where the atmosphere is already extremely tenuous -- solar and geomagnetic phenomena can have a huge relative effect.

But we're not talking about space. We're talking about the earth's atmosphere.

The proportion of reflected light is called the "albedo", which ranges from a theoretical maximum of 1 (a perfect mirror, or a theoretical white surface with no absorption) to 0 (a theoretical "black body").

White clouds reflect a lot of the incoming sunlight (have a larger albedo). Light that strikes the ground from a clear sky causes more ground heating, which causes more air heating, which causes the atmosphere to expand.

ATW, the Earth's albedo can range from about 0.9 (fresh snow on the ground) to about 0.06 (open ocean). White clouds can approach about 0.8.

Edit: the height of the tropopause (the boundary between the troposphere and the stratosphere) varies from about 9 km (over the poles) to 17 km (over the equator) due largely to the greater temperature in equatorial regions. So that layer of the atmosphere, at least, is nearly twice as thick in warm regions than it is in cold regions. See:

https://en.wikipedia.org/wiki/Tropopause