B. Water Cycle
All living things require ___ to survive. Water molecules enter the atmosphere as ___, a gas, when they evaporate from the ocean or other bodies of water. The process by which water changes from liquid form to an atmospheric gas is called ___. Water can also enter the atmosphere by evaporating from the leaves of plants in the process of ___. During the day, the ___ heats the atmosphere. As the warm moist air rises, it cools. Eventually, the water vapor ___ into tiny droplets that form clouds. When the droplets become large enough, the water returns to Earth's surface in the form of ___ like rain. On land, much of precipitation runs along the surface of the ground until it enters a river or stream that carries the run off back to an ___. Rain also seeps into the soil, some of it deeply enough to become ___. Water in the soil enters plants thought the ___, and the water cycle begins a new.