Water from the river is turning into water vapor and heading into the atmosphere.
The sun heats the water molecules making them move rapidly into the atmosphere where they start to cool. The water vapor molecules slow down and turn to liquid and return to Earth as precipitation (rain, sleet, snow).
ciAs the water vapor cools the molecules come closer together and form clouds. when the cloud gets too heavy precipitation happens( rain, sleet, snow, hail.)
The clouds get heavy with cooled water molecules and water will start to fall out of the clouds as rain, sleet, snow, or hail.