In the diagram, number 3 represents precipitation.
The diagram represents the water cycle. Water in the ocean heats up by the sun and converts into water vapor, the process is known as evaporation, represented by number 1. The water vapors formed rises up and form clouds by the process of condensation, represented by number 2. After the formation of clouds, water falls from clouds in the form of rain. This process is called precipitation which is represented by number 3.