Atmometer

An atmometer is like a water sprinkler for plants but it doesn't water them. Instead, it tells us how much water plants need. Imagine you have a straw that ends in a little sponge. You put water in the sponge and cover it with a small cap. This sponge straw is placed in a special holder and left outside in the sun.

Now, the sun is very hot and wants to drink the water in the sponge through the straw. This is called evaporation. When water evaporates, it becomes vapor, and we cannot see it anymore.

But our sponge straw has a secret. Inside the cap, there is a tiny hole that allows air to come in and replaces the water that evaporates. When this happens, we see the sponge's water level decrease.

Scientists measure how much water evaporates from the sponge straw to figure out how much water plants need in a specific area. They use this information to make sure that the plants get the right amount of water at the right time.