The Sun provides the energy to power the water cycle. When water changes state in the water cycle, the total number of water particles remains the same. The changes of state include melting, sublimation, evaporation, freezing, condensation, and deposition. All changes of state involve the transfer of energy.
Water vapor changes to precipitation and falls as rain. This process is a gas changing to a liquid. Plants absorb some of this water and excrete excess water back into the atmosphere in the form of water vapor. The Sun also causes the evaporation of liquid water in lakes, rivers, and oceans. In evaporation, liquid changes into a gas. Eventually, water vapor in the atmosphere condenses as clouds and falls back to Earth as rain. Once again, this process is a gas changing into a liquid. At low temperatures, water changes to snow or ice and falls. Here, liquid water freezes as it changes into solid water.
A biome is an area classified according to the species that live in that location. Temperature range, soil type, and the amount of light and water are unique to a particular place and form the niches for specific species allowing scientists to define the biome.
