Pileus clouds are cap-like clouds that can be used to identify thermal wave.. Good convection apparently acts like orographic barrier, wind shear hits it, forced up and moisture condences. Climb is on windward side of cumulus, from my limited experience. The Pileus often don't last very long, though the lift may still be there.

https://www.youtube.com/watch?v=mGM7kJQr0RA

https://www.youtube.com/watch?v=3eHKYWMvmWE