What is rainfall?

Rainfall is when water from the sky falls down to the ground because it got heavy enough to drop.

Imagine you're playing with a bucket full of marbles. When you tip the bucket just a little, only a few marbles roll out at first. But as more marbles fall, they pile up and make more marbles fall, until boom, all the marbles are on the floor!

That's kind of like how rain works. Water in the sky is like the marbles. When the water gets heavy enough, it falls down, that’s rainfall.

When the sun heats up a lake or ocean, some of the water turns into vapor and goes up into the air. As this vapor rises, it meets cooler air high in the sky and changes back into tiny drops of water. These drops stick together like marbles joining forces, more drops mean bigger drops, until they're too heavy to stay up anymore.

Then, plop, they fall down as rain, just like when you tip over that bucket full of marbles!