What makes a cloud form in the sky and why do some rain?

Clouds form when water vapor in the air turns into tiny drops of water, and rain happens when those drops get big enough to fall down.

Imagine you're playing with a sponge in the bathtub. When you squeeze it, water comes out, that's like condensation, which is what happens when warm, wet air cools down. The sponge is like the air; when it gets squeezed (or cooled), it lets go of some water.

Clouds are kind of like big, fluffy sponge balls up in the sky. When water vapor from the ground goes up and meets cool air high up, it turns into tiny water droplets, that's how clouds start to form.

If more water vapor keeps joining those drops, they get bigger and bigger, just like when you add more water to a sponge until it gets heavy.

Sometimes, those big water droplets become too heavy to stay in the sky. They fall down, plop! That’s rain! It's like when your sponge is so full of water that it can't hold on any longer and drops into the tub.

So clouds are just sponges made of air and water, and rain is when those sponges get too wet to stay up there.