Water is continuously circulating

The movement of water from land to ocean, from ocean to the atmosphere is called water cycle.
The sun increases atmospheric temperature on the earth. As the result, waters in land and oceans on the Earth become vapors. The vapors rise up to the atmosphere, producing clouds. When cloud particles grow and fall down, rain is made. The rain gathered and creates river flow. The part of river flow infiltrates into ground, discharging to ground water. Some of the river flows are used and the others return to oceans. The surface waters on the oceans become vapor again by the sun and repeat the water cycle. The water cycle contributes to maintaining atmospheric temperature at appropriate levels and creates natural fresh water to be beneficial for human lives. When the atmospheric temperature increases due to global warming phenomena, evaporation from ocean water causes rapid expansion of atmospheric moisture, probably resulting in the occurrence of strong typhoon.

Ice crystals

When the atmospheric temperature is below 0¡É(32¢µ), atmospheric vapors become solid ice called ice crystals.
Ice crystals or cold water drops can be joined to other ice crystals and it makes the crystal size bigger, then forming snow crystals. Ice crystals cannot be seen with the naked eyes but can be seen by microscope. Ice crystals have different shapers such as needle shape, hexagonal columns, and triangle plate.

Circulation of water

Water circulation

Evaporation	Warm waters(vapors) rise up due to solar heat.	River	Rainfall flows into rivers. The river- waters are provided to animals and plants.
Freezing	When atmospheric temperature goes down, vapors become tiny water drops and form clouds.	Ground water	Part of rainfall infiltrates into ground and forms ground water.
Rainfall (Precipitation)	Water drops in atmosphere become heavier and fall down to surface in the form of rainfall or snow.	Surface water	Rain water evaporates again and creates new clouds.