The water cycle (or hydrologic cycle) describes the continuous movement of water above, below, and on the planet. Since the water cycle is in fact a "cycle", there is no beginning or end. Water exists in three states: liquid, vapor, and ice. Although the balance of water on our planet is fairly constant, individual water molecules may come and go. The water cycle is driven by the sun. The sun heats the oceans and allows water to evaporate into the air. The sun also heats snow and ice which...
Rain is a type of liquid precipitation. It is defined as condensation of atmospheric water vapor that forms into drops that become heavy enough to fall, and often making it to the surface. Rain is the primary source of most of the fresh water in the world. Rain provides suitable conditions for diverse ecosystems, water for power sources and for crop irrigation. Not all rain reaches the surface. Some rain evaporates as it falls, especially through dry air. This type of rainfall is known as...
- A Roman unit of weight, 1⁄1728 of a pound.
- A weight of four grains used in weighing gold and precious stones; a carat.
- In anatomy, a formation suggesting a husk or pod.
- The lowest unit in the Roman coinage, the twenty-fourth part of a solidus.
- A coin of base silver of the Gothic and Lombard kings of Italy.