Heat from the SUN (1)  causes water to EVAPORATE (2) from lakes, rivers and oceans.

As the air rises it cools.  This causes the water vapour in the air to CONDENSE into tiny droplets  and  a CLOUD  is formed (3).

When the drops of water are big enough they fall as RAIN (4)

The rain water soaks into the ground and collects in rivers and flows to the sea (5).

….the Sun causes the water in the rivers and lakes to evaporate and the cycle restarts!