GEF

Unit 2  |  Water Science and the Water Cycle 49 an important greenhouse gas, holding heat close to the Earth’s surface and strongly affecting the global climate. Transpiration is the release of water vapor from the surfaces of trees and other plants. Plants actively absorb water from the soil through their roots, pull it up through their stems into their leaves, and release it into the atmosphere. Transpiration has a major influence on regional climates and weather patterns. In part because of transpiration, large forested regions such as the Amazon Basin are key regulators of global climate. Condensation is the process in which water vapor changes into liquid water when it is cooled. Near the ground, condensa- tion may form fog or water droplets on a window. Higher in the atmosphere, water droplets condense around tiny particles of dust, salt, or smoke to form clouds. Clouds strongly affect the climate by reflecting incoming solar radiation back to space. They also hold heat close to the surface of the Earth and mod- erate temperature changes between day and night. Condensation may form fog or clouds. Precipitation occurs when individual water droplets combine and become too heavy to remain airborne. Overall, the major- ity of precipitation falls as rain, with smaller amounts falling as sleet, snow, or hail. After water falls on land, it either finds its way into in streams, rivers, and lakes, or seeps into the ground and becomes groundwater. What happens to precipitation TRANSPIRATION The loss of water from the surfaces of plants. CONDENSATION The change of matter from a gas to a liquid.