What are atmospheric rivers

Atmospheric rivers are long and narrow regions in the atmosphere that basically resemble rivers in the sky, which transport most of the water vapors from the oceans to continental areas, both in the Northern and Southern Hemispheres. In the Northern Hemisphere, they occur between December and February, while in the Southern Hemisphere, between June and August and they are some of the largest and most important mechanisms for transporting water around the world.

There are several conditions that need to be met in order for atmospheric rivers to form, such as the need for strong low-level winds, which act like the highway for those water vapors, as well as high moisture levels, which are responsible for creating precipitation. Lastly, the precipitation couldn't fall back on Earth in the form of rain without orographic lift, a phenomenon which causes the moist air to move to higher altitudes, where it cools down, creating clouds and thus, rain.

According to Euronews.green, the area they provide rain to has extended by 2-6% since 1980, but the problem is that they usually bring too much water for the soil to handle. This is because of climate change, as the air is warmer than in previous years or decades, meaning that more precipitation forms.

Lexi Henny, an atmospheric scientist at the University of North Carolina, said that "this doesn’t mean that it's necessarily all because of climate change. We didn’t study that, but it does line up, broadly speaking, with some expectations of how (atmospheric rivers) will change in a warming atmosphere."

Atmospheric rivers advantages and potential dangers

It's worth noting that most atmospheric rivers don't cause any trouble for the environment or for us, in general, quite the contrary in fact. They provide much needed precipitation for the land, watering the farming fields we cultivate and stabilizing the soil, while also feeding the forests and plants with water.

In fact, Earth.org notes that only 1.2% of the world's freshwater reserves are represented by surface water, meaning that a global redistribution system (i.e. atmospheric rivers) is crucial to replenish our watersheds, as well as to conserve the biodiversity.

At the same time, during cold months, the precipitation from atmospheric rivers is stored as snow packs, which melt during spring, replenishing water reserves and stabilizing river levels

But, as with other extreme weather events, atmospheric rivers are only beneficial so long as they don't grow too much, which again, due to climate change, can be more frequent than in the past. Some of the biggest dangers that can occur as a result of extreme atmospheric rivers and high precipitation from these phenomena are landslides and floodings.

Soil is only capable to absorb a certain amount of water and especially without vegetation, it will saturate very quickly, leading to flooding. Additionally, the lack of vegetation, either from deforestation or a wildfire, will cause the land to become unstable and if on a slope, it will be causing a landslide.

The lack of atmospheric rivers is also considered an extreme weather event, as it means that precipitation won't travel where it should, leaving certain areas vulnerable to drought and threatening agriculture or the ecosystems.

Atmospheric rivers can and do take place pretty much around the world, but there are several locations where they are more frequent and can cause more trouble, such as California, which is one of the hot spots for these events. In fact, back in around 1862, state officials had to temporarily move the capital from Sacramento to San Francisco after a massive flood took place following an extreme atmospheric river.

In 2022, New Zealand faced significantly high precipitation after an atmospheric river passed through the country. Tākaka, a small town in the South Island of New Zealand, received one-third of its average annual rainfall in only three days and between the end of 2022 and May 2023, California experienced 12 atmospheric river events.

How to prepare for an atmospheric river

Preparing for an atmospheric river event is very similar to preparing for a flooding, as this is the actual result of a violent atmospheric river. We covered this in one of our previous articles on extreme weather events, but to keep things brief, here are a few things to consider.

When building a house in a flood-prone area, make sure that the actual building is elevated, no matter how little the elevation may be. Also, avoid displacing any electrical or important equipment between the ground and the base of the house.

Don't try to run or drive, as this is what causes a lot of fatalities during a flood. If your car is in an underground parking lot and you think about saving it, think of something else, because it's not worth risking your life for it. Chances are it's already flooded and will be declared totaled anyways by the insurance company. Swimming is also a bad idea, due to the strong currents that can and most likely will form, especially on narrow streets and alleyways.

Finally, keep up to date with the weather forecast, especially during the months when you know an atmospheric river is likely to hit and just in case you need to evacuate, establish a quick escape route to follow.

And now you know, hearing about atmospheric rivers isn't necessarily a bad thing, as they help stabilize our ecosystems and provide us with the much-needed freshwater that we need for consumption, as well as for farming. However, if things get out of control, you should also be well-prepared to protect your home and your life.