Are clever clouds getting brighter? Some (all?) of it seems linked to our plasma stars activity and the Sun Earth connections.
The Noctilucent clouds (polar mesospheric clouds) have been getting bigger and brighter since the 1980s/1990s, when we started to scientifically observe them.
DeLand, an atmospheric scientist with Science Systems and Applications Inc. and NASA's Goddard Space Flight Center, has found that polar mesospheric clouds are forming more frequently and becoming brighter. He has been observing the clouds in data from Solar Backscatter Ultraviolet instruments that have been flown on satellites since 1978. The graph shows how the brightness of the clouds has changed in the Northern Hemisphere.
For reasons no one fully understands, the brightness wiggles up and down in step with solar activity, with fewer clouds forming when the Sun is most active.
The biggest variability is in the far north. Underlying the changes caused by the Sun, however, is a trend toward brighter clouds.
Night-Shining Clouds are Getting Brighter | Earth Observatory NASA
And there are more of them now. Watch out for them.