sublimation is the process by which a substance undergoes conversion from the solid phase to the gas phase, without going through an intermediate liquid phase. Iodine crystals and solidified carbon dioxide are examples of substances that sublimate at room temperature and regular atmospheric pressure. By contrast, at normal pressures, most chemical compounds and elements possess three different states—solid, liquid, and gas—at different temperatures. In these cases, the transition from the solid to the gaseous state requires an intermediate liquid state. The antonym (opposite process) of sublimation is calleddeposition. The formation of frost is an example of meteorological deposition.