Geography

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Water is naturally cycled through the hydrologic cycle . The hydrologic cycle is the continuous process by which water moves through the living and nonliving parts of the environment . In the hydrologic cycle , water moves from bodies of water , land , and living things on Earth 's surface to the atmosphere and back to Earth 's surface . The sun is the source of energy that drives the hydrologic cycle (Mcknight ,

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Water moves continuously through the hydrologic cycle . The cycle has no real beginning or end . A single water molecule can be

traced through one complete water cycle . Consider a molecule of water floating near the surface of an ocean . The sun is shining and the air is warm Soon the molecule has absorbed enough heart energy to change state . It evaporates and becomes water vapor . Evaporation is the process by which molecules at the surface of a liquid absorb enough energy to change to the gaseous state . Although the water comes from the salty ocean , it becomes fresh through the process of evaporation . The salt remains in the ocean (Mcknight ,

.242 . Large amounts of water evaporate constantly from the surfaces of ocean and large lakes . Small amounts evaporate from the soil , puddles and even from the skin . A significant amount of water is given off by plants . Plants draw water from the soil through their roots Eventually the water is given off through the leaves as water vapor in a process called transpiration . Once a water molecule has found its way into the atmosphere , warm air carries it upward . Higher up , the air tends to become much colder . Cold air holds less water vapor than warm air . Some of the water vapor cools and condenses into liquid water Condensed droplets of water clump together around tiny dust particles in the air , forming clouds

As more water vapor condenses , the water droplets in a cloud eventually become so heavy that they fall back to Earth . Water that falls to the Earth , as rain , snow , hail , or sleet is called precipitation . Most water molecules probably spend only about 10 days in the atmosphere before falling back to Earth . Most precipitation falls directly into the oceans . Water in the ocean may stay there for many years before evaporating , continuing the cycle . When precipitation falls on land some of the water evaporates again immediately . Some runs off the surface of the land into rivers and lakes . From there , it many eventually evaporate or flow back into the ocean . Some water trickles down into the ground and forms groundwater . Groundwater may move underground until it reaches a river , lake , or ocean . Once groundwater reaches the surface , it can continue through the cycle by evaporating again

Water underground trickles down between particles of soil and through cracks and spaces in the layers of rock . Different types of rock and soil have different sized space or pores , between their particles . How easily water moves through the material depends not only on the size of the...