Extreme evaporation

A cup of boiling hot water thrown into very cold air will almost instantly freeze in midair and create a shower of tiny ice crystals. There are several reasons behind this phenomenon.

First, the near-boiling water is already close to becoming steam when it is thrown into the air, which means that the water molecules are much closer to evaporating into the vapor state than they would be if the water were cold.

Second, the act of throwing the water into the air causes it to break up into tiny droplets. The water that was contained in the cup (which originally had a relatively small surface exposed to the air) now experiences a tremendous increase in the total surface area exposed to the air. This situation helps to speed up the evaporation process (evaporation is the process of turning from a liquid to a vapor).

Finally, very cold air typically has a low humidity level (that is, a low amount of water vapor present). This is yet another factor aiding the transition from liquid water, to water vapor, to ice crystals. At sufficiently low temperatures, this process seems to occur almost instantaneously.

Category:

Education

Tags:

• Science
• Cold
• Boiling