The Water Cycle, also known as the hydrologic cycle, describes the process of how water naturally moves through Earth’s environment. Liquid water evaporates into water vapor (mostly from the oceans), condenses to form clouds, and precipitates back to earth in the form of rain and snow. Liquid water flows across the land surface (runoff), into the ground (infiltration), and through the ground (groundwater). Solid ice and snow can turn directly into water vapor (sublimation). Although the Earth’s water is constantly moving, it is instructive to determine about how much water is stored in each location at a given time. Water movement, distribution, and residence times will be explored in the first lesson of this series. The impacts of human activity on the water cycle will be explored in the second lesson. Because of the emphasis on groundwater in this lesson series, the third lesson deals with groundwater availability.