a definition of the water cycle
Water on earth today has been here for millions of years. Because of the water cycle, water moves from the earth to the air to the earth again. It changes from solid to liquid to gas, over and over again. Precipitation: The Water Cycle. New! Water cycle for kids poster. Precipitation is water released from clouds in the form of rain, freezing rain, sleet, snow, or hail. It is the primary connection in the water cycle that provides for the delivery of atmospheric water to the Earth. Most precipitation falls as rain. The water cycle or hydrologic is a continuous cycle where water evaporates, travels into the air and becomes part of a cloud, falls down to earth as precipitation, and then evaporates again. This repeats again and again in a never-ending cycle. The Water Cycle Vocabulary List The Water Cycle: The change and movement of the Earth ˇs water from liquid to vapor to solid. The water cycle is solar powered. Oceans: store most of the Earth ˇs water. Over 70% of the Earth ˇs surface is ocean; it contains 96.5% of the world ˇs water supply. Evaporation: occurs when the sun heats water up and it becomes vapor in the air. Condensation is the opposite of evaporation; it occurs when air cools and the vapor collects into liquid form. Precipitation: is condensation falling onto land in the form of rain, sleet, hail, snow, and mist. Evapotranspiration: occurs when water is discharged as vapor into the atmosphere as a result of evaporation from the soil and transpiration by plants. Transpiration is how water is carried through the plants from the roots. The stomata on the underside of leaves allows water to escape into the air. Water keeps moving and changing from a solid to a liquid to a gas, over and over again. Precipitation creates runoff that travels over the ground surface and helps to fill lakes and rivers. It also percolates or moves downward through openings in the soil to replenish aquifers under the ground. The water cycle, also known as the hydrologic cycle or the H2O cycle, describes the continuous movement of water on, above and below the surface of the Earth. Although the balance of water on Earth remains fairly constant over time, individual water molecules can come and go, in and out of the atmosphere. These areas are usually close to oceans or large bodies of water that allow more water to evaporate and form clouds. Other areas receive less precipitation. Often these areas are far from water or near mountains. As clouds move up and over mountains, the water vapor condenses to form precipitation and freezes. The water in your glass may have fallen from the sky as rain just last week, but the water itself has been around pretty much as long as the earth has! When the first fish crawled out of the ocean onto the land, your glass of water was part of that ocean. People perspire (sweat) and plants transpire. Transpiration is the process by which plants lose water out of their leaves. Transpiration gives evaporation a bit of a hand in getting the water vapor back up into the air. Water vapor in the air gets cold and changes back into liquid, forming clouds. This is called condensation. You can see the same sort of thing at home... Pour a glass of cold water on a hot day and watch what happens.
It is a continuous cycle where water evaporates, travels into the air and becomes part of a cloud, falls down to earth as precipitation, and then evaporates again.