(WANE) — You’ve probably heard all about southern California’s major flooding event and the seemingly never-ending rainfall in that area. But, what’s causing that? It’s a phenomenon called an Atmospheric River.
Atmospheric rivers are defined by NOAA as “A relatively long, narrow region in the atmosphere, like a river in the sky, that transports water vapor outside of the tropics.” These rivers come in all shapes, sizes, and strengths.
According to NOAA, the average river carries an amount of water vapor that is roughly equivalent to the average water flow at the mouth of the Mississippi River. The strongest rivers can transport up to 15 times that amount.
Let’s dive into how these rivers work, and why California in particular is prone to these events.
As this giant band of moisture pushes over land, the moisture is forced to rise upwards due to the mountains/elevated terrain in California. As the moisture rises over the mountains/elevated terrain, the water vapor condenses into rain, and occasionally snow, if cold enough.