he water cycle is powered by energy from the sun and involves three major processes-evaporation, pre cipitation, and transpiration. Incoming solar energy causes evaporation of water from the oceans, lakes, rivers, and soil. Evaporation changes liquid water into water vapor in the atmosphere, and gravity draws the water back to the earth's surface as precipitation(rain, snow, sleet, and dew). Over land, about 90% of the water that reaches the atmosphere evaporates from the surfaces of plants, through a process called transpiration, and from the soil.