Eli5 — How does water decide which water will be on top, in the middle and on the bottom?

Question

This goes from the ocean to as simple as a glass of water. Are certain molecules bigger and heavier and therefore sink to the bottom while smaller ones float on top? If there is water in a glass and I pour more in, does the added water push the other to the top, sit on top of the original or is it truly just random and it mixes in and settles where ever it does and there’s no ryhme or reason to it

In: 8

Answer 1

There are currents in the ocean caused by temperature changes and the rotation of the earth. A water molecule is just that. They aren’t bigger or smaller.

In the glass of water. The temperature differential will be the primary order of where the molecules go until equilibrium is reached. And then it’s just random.