Thanks to search engine magic, I found a few from the pilot/photographer I was thinking of. I'm sure they have much cleaner windows that the passengers do!
One other impressive time I recall was flying from Kansas City back to Minneapolis at near sundown and seeing some isolated, relatively small but very energetic climbing updrafts making an impressive series of one after another that we were passing by. I thought we were in for a tooth-rattling ride, but it was as smooth as silk, and after sunset they calmed down. No lighting which was a huge disappointment, but still memorable. Smart phones weren't common or exist at all, so I have no images except in my mind.
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