Noctolucent is a much more suitable term for the clouds, thank you! Regarding your observation of more of such clouds i don't have any data or comparison in the past. But pollution in atmosphere has this paradox effect. Once i was in Michigan and drove to the north in direction of Canada i had a deep experience with bright orange colored sky. It was short before heavy rain there. I'd never seen that before in my life or in germany. After that someone told me it's because of the air pollution in that area.But it looked so fantastic as everything was tinted in orange.. my car, the trees, street, houses, the sky.. 🌆