| A | B |
|---|
| water vapor | Water in the form of an invisible gas. |
| humidity | The amount of water vapor in the air. |
| evaporate | To change state from a liquid to a gas. |
| condense | To change state from a gas to a liquid. |
| precipitation | Any form of water that falls to the earth from a cloud. |
| runoff | Water that falls onto the land and drains off the surface. |
| atmosphere | The layer of gases that surrounds the earth and contains clouds. |
| hydrosphere | The water part of the earth's surface. |
| lithosphere | The rigid outer part of the earth's surface. |
| cloud | A collection of water droplets and/or ice crystals and dust particles. |
| heat | A form of energy transfer between two systems with different temperatures. |
| air | A mixture of gases that make up the earth's atmosphere. |
| transpiration | The passage of watery vapor from a living body through a membrane or pores. |
| dew | Condensation in the form of small water droplets that form near the ground when the temperature has fallen to the dew point. |
| groundwater | Water beneath the surface of the ground. |
| dew point | The temperature to which the air must be cooled at constant pressure to become saturated. |
| percolation | The slow movement of water through the pores in soil or permeable rock |
