Temperature Diff.

– The Temperature Difference setting controls how much the parameter Object Flow’s Temp. Diff. affects the smoke. Higher value results in faster rising (or sinking, see Object’s Flow Temp. Diff.) smoke.
– The higher this value, the more the smoke is affected by Object’s Flow Temp. Diff.
– Temp. Diff. = 0 means that Object’s Flow Temp. Diff. does not affect the smoke.

Blender Smoke Temp Diff