Would a circular lake have enough of sea breeze strong to create a gentle vortex in the center of the lake? Is there such a place on Earth where lake micro climate vortexes occur frequently? The Vortex would still be a breeze and not visible during normal Lake Breeze conditions.
https://worldbuilding.stackexchange.com/questions/108896/could-a-city-be-built-out-of-balloons