Question

why does smoke always rise up into the air​

Answer 1

Smoke goes up because it is lighter than air. ... In the case of smoke, it's density is less than that of the surrounding air, and thus it rises. The same goes for a hot air balloon. The density of the hot air trapped inside a balloon is less than that of the surrounding cooler air.

Answer 2

It is because smoke produce by burning something hence it is hot and hot gases raise up in air