What’s the situation in California?
California, USA, received a lot of rain in February 2024 and the first week of March. This rain caused floods and damage. California usually has long periods of droughts. So, why did this much rain happen?
It turns out that something called 'atmospheric rivers' often brings California its heaviest rain, snow, and floods. You know about rivers on land, but what are atmospheric rivers? Let’s find out.

What are atmospheric rivers?
Atmospheric rivers are like thin streams of water vapour in the sky. They form over warm oceans and move to different places carrying lots of water vapour. The sun heats up the ocean, making water evaporate into the air and form atmospheric rivers. When they reach land, the water vapour cools and turns into rain or snow.
In California, about half of the rain and snow is caused by atmospheric rivers. Atmospheric rivers also play an important role in maintaining the world’s water supply.
What role do atmospheric rivers play?
Atmospheric rivers are a part of the global water cycle, bringing rain and snow to many parts of the world. They fill up lakes and make sure there's enough snow in the mountains. This is very important for farming.
But, sometimes, these rivers cause big floods, which can hurt people and animals and cause lots of damage. This happens when climate change affects the timing and distribution of atmospheric rivers. As the world gets warmer, the moisture content in the air increases, leading to a rise in atmospheric rivers.
These changes could cause floods in places that don't usually get much rain, which is harmful. That's why we all need to fight climate change to keep the Earth healthy for the future.