Plants break down part of the water into oxygen and hydrogen during photosynthesis. However, much of the water that is returned to the atmosphere as water is lost from the pores in the leaves of plants. When plants and animals die, the water in their tissues is released back into the environment. Water vapour returns to the atmosphere through the pores of plants. Water vapour is also collected from the soil's surface by drying winds.
Most water is returned to the atmosphere by evaporation from the oceans, lakes, and ponds.
The warmth of the sun and the strength of the wind are the main factors affecting the rate of evaporation. Once in the atmosphere, the water vapour condenses and forms clouds. Then the cycle begins again.