The process of sublimation is the transformation of a solid substance into a gaseous phase without first traversing through a liquid phase. Typically, when solid matter changes its physical state as it is heated, it first becomes a liquid. Then as more heat energy is applied, the liquid becomes a gas. When sublimation takes place, however, the solid immediately becomes a gas and no melting occurs. A good example is the sublimation of solid carbon dioxide. Carbon dioxide, the gaseous compound found in our atmosphere that is exhaled during respiration, is a solid at very cold temperatures. Solid carbon dioxide is called dry ice because, at ordinary pressures, it sublimates into a gas without first passing through a liquid phase. The opaque carbon dioxide vapor that emanates from dry ice is very cold compared to room temperature air, and thus flows downward, in a manner opposite of steam...