Question

why does smoke always rise up into the air. ​

Answer 1

Answer:

Explanation:

This is because of the heating of the earth's surface during the day. The air just above the surface becomes heated and expands. In turn, it begins to rise, since it is lighter, resulting in vertical movement in the atmosphere. The more unstable, the higher smoke will be lifted.

Answer 2

On heating air expands and occupies more space. When air occupies more space, it becomes  lighter. The warm air is therefore lighter than the cold air. The lighter, warm air rises up. This  is the reason why smoke always rises up.