A raindrop is a single drop of water that falls from a cloud during a rainstorm. Each raindrop forms when tiny water droplets high in the atmosphere collide and stick together until they become heavy enough to fall to the ground.

Raindrops aren't actually shaped like teardrops, the way they're often drawn in pictures. Small raindrops are nearly round, like tiny spheres. Larger raindrops get flattened on the bottom by air resistance as they fall, making them look more like hamburger buns. The biggest raindrops are about as wide as a pencil eraser, and they fall at around 20 miles per hour.

You can feel individual raindrops hitting your face during a light rain, but during a heavy downpour, so many raindrops fall so quickly that they seem to blend together into sheets of water. Scientists who study weather measure rainfall by tracking how much water falls in a certain area, which tells them whether a region is getting enough water for crops and rivers, or if there might be flooding ahead.