The word precipitation means all the types of moisture which are naturally deposited on the Earth's surface. Of these, rain is by far the most important.
Rainfall occurs when the water vapour in the air condenses.
These droplets of water can be seen in the sky as clouds. If the droplets become large enough they fall to the ground as rain. Rain falling on the funnel is collected in a bottle and this is measured each day. We use a bar graph to record the total rainfall. As this air has spent many days crossing over the Atlantic Ocean, it is full of moisture.