Question

Fill the Gaps:
Instead of becoming clouds, _____ ______ changes directly into ice without ever becoming a ______. This forms ___ _______.

Answer 1

Answer:

Explanation: Solid, liquid, and gas - the three states of water. We see water freeze and turn to ice and we see water evaporate and turn to gas but... have you ever seen ice evaporate directly to gas? This process is called sublimation and you can read all about it below.

Sublimation is the conversion between the solid and the gaseous phases of matter, with no intermediate liquid stage. For those of us interested in the water cycle, sublimation is most often used to describe the process of snow and ice changing into water vapor in the air without first melting into water. The opposite of sublimation is "deposition", where water vapor changes directly into ice—such a snowflakes and frost.

It is not easy to actually see sublimation occurring, at least not with ice. One way to see the results of sublimation is to hang a wet shirt outside on a below-freezing day. Eventually the ice in the shirt will disappear. Actually, the best way to visualize sublimation is to not use water at all, but to use carbon dioxide instead. If you don't know what I mean, then look at this picture of dry ice. "Dry ice" is actually solid, frozen carbon dioxide, which happens to sublimate, or turn to gas, at a chilly -78.5 °C (-109.3°F). The fog you see is actually a mixture of cold carbon dioxide gas and cold, humid air, created as the dry ice "melts" ... oops, I mean sublimates.