What Is an "Atmospheric River"?

A flooded playground in San Jose, California, on February 22. Blame the high water on an atmospheric river. Image Credit: Noah Berger/AFP/Getty Images

 
Storms make for attention-grabbing headlines, and almost every disaster has a meteorological term that makes a hazardous situation sound 10 times as terrifying. A derecho tore through the Mid-Atlantic back in 2012 and had such a profound psychological impact on the affected residents that you could cause mass hysteria by just mentioning the term. Then came the dreaded polar vortex, an ever-present large-scale wind pattern that encircles the North Pole and occasionally gets wavy and injects bitterly cold air into southern Canada and the United States. It was nothing new—but it sounded scary, so the name took off.

The recent deluges in California highlighted the latest captivating weather-y buzzword: an “atmospheric river.” Like its counterparts, this scary-sounding phenomenon is not as uncommon as it seems. It's responsible for almost all of the rain on the West Coast this winter.

Clouds outline the atmospheric river stretching from Hawaii to California in the storm that affected the West Coast on February 17, 2017. Image Credit: Dennis Mersereau

 
So what is it? An atmospheric river is a long, narrow band of deep tropical moisture that can span thousands of miles in length. They occur from the tropics to the mid-latitudes. Atmospheric rivers aren’t actual rivers, of course, but it’s a pretty good description of a feature that resembles a river on satellite imagery and can bring torrents of water to the unlucky communities caught beneath one as the system comes ashore.

These ribbons of tropical moisture are the result of sprawling low-pressure systems that form just far enough south that their counter-clockwise circulation scoops up water vapor from the tropics and transports it northward. The storms that cause atmospheric rivers to form in the first place are usually able to generate enough upward lift to create precipitation. Mountains can play a role—they're very effective at wringing moisture out of the atmosphere as wind travels up the side of their terrain. Whether it’s rain or snow, any precipitation that forms within that band of elevated moisture levels can be quite heavy, producing steep rainfall totals and many feet of snow in extreme cases.

NASA’s Global Precipitation Measurement (GPM) mission captured three weeks of heavy rainfall slamming into the West Coast between February 1 and February 20, 2017. Watch it happen in the video below.

California has a reputation for calm, sunny weather, but the state never really has it easy when it comes to dealing with nature’s temper tantrums. For the past couple of years, the state has been mired in a devastating drought, a cycle of dryness that was finally broken this winter as one storm after another roared in from the Pacific and drenched the state with unmanageable amounts of heavy rain. The driving force that gave each storm its bulk was an atmospheric river. Without it, there wouldn’t have been much moisture for the storm systems to work with.

An atmospheric river that affects the West Coast—and California in particular—is usually nicknamed the “Pineapple Express” since the source of the tropical moisture is the area around Hawaii. Though they go without a popular nickname, these features are also common over the eastern half of the United States during the warm season. Many of the major flash floods that occur in the eastern U.S. during the summer months are the result of intense thunderstorms tapping into the bountiful moisture present in an atmospheric river flowing over the region.

All weather is the result of nature trying to balance out inequality, and atmospheric rivers, just like every other weather condition, serve this purpose. Wind blows from areas of high air pressure to areas of lower pressure in an attempt to erase the inequality of more air molecules over one spot than another. The jet stream is the direct result of sharp temperature differences between the tropics and the poles. Hurricanes exist to transport heat from the tropics to the poles. Atmospheric rivers exist to take moisture out of the tropics and spread it around the world. Though they can seem difficult to enjoy, we’d be in some pretty big trouble without them. In 1998, a study by MIT scientists reported that 90 percent of all the moisture transfer between the tropics and the rest of the world each year occurs within these narrow bands of evaporated paradise.

Amazon's Under-the-Radar Coupon Page Features Deals on Home Goods, Electronics, and Groceries

Stock Catalog, Flickr // CC BY 2.0
Stock Catalog, Flickr // CC BY 2.0

This article contains affiliate links to products selected by our editors. Mental Floss may receive a commission for purchases made through these links.

Now that Prime Day is over, and with Black Friday and Cyber Monday still a few weeks away, online deals may seem harder to come by. And while it can be a hassle to scour the internet for promo codes, buy-one-get-one deals, and flash sales, Amazon actually has an extensive coupon page you might not know about that features deals to look through every day.

As pointed out by People, the coupon page breaks deals down by categories, like electronics, home & kitchen, and groceries (the coupons even work with SNAP benefits). Since most of the deals revolve around the essentials, it's easy to stock up on items like Cottonelle toilet paper, Tide Pods, Cascade dishwasher detergent, and a 50 pack of surgical masks whenever you're running low.

But the low prices don't just stop at necessities. If you’re looking for the best deal on headphones, all you have to do is go to the electronics coupon page and it will bring up a deal on these COWIN E7 PRO noise-canceling headphones, which are now $80, thanks to a $10 coupon you could have missed.

Alternatively, if you are looking for deals on specific brands, you can search for their coupons from the page. So if you've had your eye on the Homall S-Racer gaming chair, you’ll find there's currently a coupon that saves you 5 percent, thanks to a simple search.

To discover all the deals you have been missing out on, head over to the Amazon Coupons page.

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5 Ways to Help Victims of the West Coast’s Wildfires

A wildfire near Shaver Lake, California, earlier this month.
A wildfire near Shaver Lake, California, earlier this month.
David McNew/Getty Images

Wildfires continue to ravage millions of acres across California, Oregon, and Washington, and strong winds forecasted in some of those regions could aggravate the blazes. To prevent future fires, we need to focus on combating climate change through policy reform and sustainable living. But for people directly affected by the fires, their current needs are much more urgent: food, shelter, and funds. Here are five organizations that can help you help victims.

1. Red Cross

The Red Cross has about 600 workers coordinating meal distribution, installing victims in shelters and hotels, and providing other support across Northern California. You can donate to the cause by choosing “Western Wildfires” under “I Want to Support” on the donation page here.

2. GoFundMe

GoFundMe’s affiliated nonprofit, GoFundMe.org, has created a Wildfire Relief Fund for this particular outbreak of fires on the West Coast. You can make a donation to the overall fund here, or you can explore the separate hubs in the description to find individual GoFundMe pages to give to.

3. Los Angeles Fire Department Foundation

Unfortunately, the city of Los Angeles doesn’t allocate enough public funds to the fire department to equip firefighters with all the important gear they need. The Los Angeles Fire Department Foundation tries to fill those demands by providing things like hydration backpacks, thermal-imaging cameras, brush-clearing tools, and more. You can donate to the general fund here, or choose a specific fire station from the dropdown menu.

4. VEMAnet

VEMAnet (Volunteers for the Emergency Management of Animals Network), is an offshoot of the Good Shepherd Foundation, which links animal owners who need emergency help with volunteers who can transport and/or house their animals—anything from cats to cattle—temporarily. You can post details about what animals you can accommodate here; and if you or someone you know needs help evacuating any pets, you can request help or browse available listings here.

5. California Fire Foundation

The California Fire Foundation’s Supplying Aid to Victims of Emergency (SAVE) program distributes $250 gift cards to wildfire victims, so they can decide for themselves what their most pressing needs are. You can donate here.