| A | B |
|---|
| Evaporation | The process by which molecules at the surface of a liquid, such as water, absorb enough energy to change to a gaseous state, such as water vapor. |
| Precipitation | Forms of water such as rain, snow, sleet, or hail that fall from clouds and reach Earth's surface. |
| Condensation | The process by which a gas, such as water vapor, changes to a liquid, such as water. |
| Groundwater | Water that fills the cracks and pores in underground soil and rock layers. |
| Divide | A ridge of land that separates one drainage basin or watershed from another. |
| River | A large stream. |
| Tributary | A stream that flows into a larger stream. |
| Drainage Basin | The land area from which a river and its tributaries collect their water. |
| aquifer | An underground layer of rock or soil that holds water. |
| artesian well | A well in which water rises because of pressure within the aquifer. |
| saturated zone | A layer of permeable rock or soil in which the cracks and pores are completely filled with water. |
| unsaturated zone | A layer of rocks and soil above the water table I which the pores contain air as well as water. |
| water cycle | The continuous process by which water moves from Earth's surgace to the atmosphere and back, passing through the living and nonliving parts of the environment. |
| Water table | The top of the saturated zone, or depth to the groundwater in an aquifer. |
| water vapor | The invisible, gaseous form of water. |
