Motion of water bubbles at the surface of hot water

[Log]

I've been thinking about this now and then, when boiling water. As the water becomes hotter the bubbles are rising in increasing numbers. The bubbles seem to either repel each other or merge to form bigger bubbles (or pop on contact) and then they seem to be moving toward the edge of the pot. After a while they pop.

This motion doesn't seem totally random, is it explained in some sort of theory?
Is this an example of brownian motion? (don't know what it is, but have heard it several times)

(title is wrong, should obviously be air bubbles in water)

 

[LightHero]

Yes, the motion of air bubbles in boiling water is an example of Brownian motion. Brownian motion is the random movement of particles suspended in a fluid due to the bombardment of molecules of the fluid itself. In the case of boiling water, the air bubbles are pushed around by the randomly moving molecules of the hot water, resulting in the bubbles appearing to move in a random direction. The bubbles may also merge with others and form larger bubbles which then move towards the edge of the pot. This is due to the fact that the surface tension at the edge of the pot is lower than in the center of the pot.