Warm rising air currents (8)

I believe the answer is:
thermals
(Other definitions for thermals that I've seen before include "Warm clothes" , "for gliders?" , "Warm underwear" , "Long johns" , "Upward air currents - winter warmers" .)
I believe the answer is:
thermals
(Other definitions for thermals that I've seen before include "Warm clothes" , "for gliders?" , "Warm underwear" , "Long johns" , "Upward air currents - winter warmers" .)