The Mpemba effect

Hey,

So we have the Mpemba effect, which most of you have probably heard.

The Mpemba effect is how hot water freezes faster than cold water. But not like this:

8oz of water at 90°c, marked a, is put in a freezer. Another 8oz of water at 30°c, marked b, is put in the same freezer, at the same time. 5 minutes later, when the freezer was opened, the cup marked a was frozen and the cup marked b was not.

No. we are talking about the rate that it freezes, not the overall time.

This happens because heat goes up and cold goes down.

So you put your cold water in the freezer, and as it is in there, the cold water goes down, and the warmer water goes up. After some time we get some small pieces of ice. This ice floats to the top, as it is less dense the liquid water, and after some time we get water.

Now you put a cup of hot water in the freezer, and when it is in there the heat travels up, forcing the colder air down to the water, due to diffusion in the air, causing more colder air to hit the top of the cup. Now because we have that cold air, it cools the water,  so the top is now colder than the bottom, and we have the colder water go to the bottom and the hotter to the top. this goes on and on and on, which makes the cooling process go by faster.

And that is the answer to the Mpemba effect.

as always,

Scientifically,
-Connor