Why does smoke rise?

Question

I thought that smoke was composed of miniscule particles of the burning material. This should make them heavier than air, and they should drop.

Answer 1

As you probably know, smoke is made of a lot of tiny particles -- mostly solid, some liquid --
suspended in air. The particles are a lot heavier (more dense) than air, so why don't they sink out
and go down rather than going upward?

Here is an explanation of sorts:

A fire makes things hot. Above a fire, you get quite a lot of hot air. Hot air is less dense than cool
air, so it rises. Because there is quite a lot of hot air, it makes quite a big wind current as it rises,
and that drags the smoke particles upward with the air, in much the same way as wind can raise
dust. Some of the smoke particles are very small indeed, so they can be held up in the air for quite
a long time, and they do not settle out from the air until a long time after they leave the fire, and
usually some distance away from the fire.

Explanation by John Christie, Faculty, Dept. of Chemistry,

Answer 2

Why Does Smoke Rise

Answer 3

Smoke, although consisting of particles that are DENSER than air, rises because it is carried upwards on the hot gases produced during combustion - it's these hot gasses that are less dense than the surrounding air: hence they rise. Once the hot air/gases cool to the temperature of the surrounding air, the smoke particles fall towards the ground.

Answer 4

Smoke rises because it is actually lighter than air. As solids burn and the gases are released, they carry these particles with them. The gases are heated, which means that they are expanding (and thus, lighter than air). When the gas temperatures drop sufficiently, the particulate matter falls to the ground in the form of the ashes you see. You see?

Answer 5

Smoke has more Kinetic Energy(due to heating) and hence rise up.

Answer 6

Yes, the particles are heavier, but heated objects become less and less dense as the molecules move faster. The less dense smoke rises above the more dense/cooler air.

Answer 7

Smoke is made up of particles of the unburned material. The unburned material is warmer than the air around it, thus warming up the air. Since the molecules in warmer air bounce more rapidly off of one another, the warmer air containing the smoke rises.

Answer 8

heat rises