Of all the water on the earth, only 0.7 % is fresh water. The rest of the water is stored in the oceans (97.2%) and ice caps (2.1%).
Of the 0.7% fresh water, 0.1 is found in the rivers, 0.6 is stored in the ground as soil moisture and ground water and 0.001 is found in the atmosphere.

Even though only a small amount of water is found at any one time in the atmosphere, this is the main mechanism for the movement of water.

Water evaporates from the oceans into the air. It then travels across the land. As it rises, it cools and forms clouds. The water then falls as precipitation. (Rain, snow, hail etc.)
Several things can then happen to the water. It can.....

• Soak into the ground
  This water eventually makes its way into rivers and to the sea or re-evaporates into the atmosphere.
• Get absorbed by plants and trees.
  These release the moisture back into the atmosphere by evapotranspiration
• Run into rivers and lakes
  These eventually bring the water back to the seas and oceans.