cloud of ashes
Specifically the cloud of ash that rises when water is poured onto a fire, such as a campfire or bonfire.
When we poured water on the campfire, a cloud of ashes rose up.
Standard kanji spelling.
Mixed kanji-kana spelling, easier to read.
Compound of 灰 (hai, 'ash') and 神楽 (kagura, 'kagura dance'), likely from the image of ashes dancing up like a kagura performance.