What Is the Jet Stream, and How Does It Work?

Trapped between two big high-pressure systems, Hurricane Harvey has stalled over Houston, to devastating effect. As the Washington Post notes, if the jet stream were to dip far enough south, it could push Harvey out. Unfortunately, that's not in the forecast.

But what is the jet stream?

A jet stream is a swift current of air that encircles the globe right around the cruising altitude of a commercial airplane. It's easy to forget that there are vast rivers of wind whooshing just a few miles above our heads at speeds that could put most hurricanes and tornadoes to shame, but jet streams affect us every day without our realizing it. These speedy winds drive or influence just about every weather system that we have the pleasure—or misfortune—of experiencing. Planes even use it to cut down on fuel consumption and travel times.

There are usually two jet streams in each hemisphere, the polar jet and the subtropical jet. When we talk about "the jet stream," we're generally talking about the stronger polar jet stream, because most of our weather is driven by it. It's typically found at the same latitude as the U.S.-Canadian border.

We're often guilty of oversimplifying weather events by blaming everything on a clash between warm air and cold air, but temperature gradients really do have an enormous impact on where the jet stream forms and how strong it is. Jet streams form as air in the upper atmosphere moves from south to north and gets deflected to the east by the Coriolis effect. The jet stream will get stronger if the warmer temperatures are to the south and the colder the air is to the north. This is why the jet stream strengthens and dips over the United States during the winter, while it weakens and retreats north into Canada during the heat of the summer.

The jet stream drives our weather through phenomena called troughing, ridging, and jet streaks. Troughs and ridges are curves in the jet stream that are analogous to low pressure (troughs) and high pressure (ridges). In the northern hemisphere, a trough is a southward dip in the jet stream and a ridge is a northward hump in the wind current. You can expect active weather ahead of a trough and quiet weather beneath a ridge.

A jet streak is an area of much faster winds within the jet stream itself. Winds in a jet stream routinely climb above 100 mph, but the wind in a jet streak can clock speeds of more than 200 mph in a boisterous weather pattern. Troughs and jet streaks often team up to create low-pressure systems at the surface, and that's what gives birth to most of our interesting weather. Winds don't flow in a straight line as they twist around a trough or speed in and out of jet streaks. Air collides going into a trough and diverges as it leaves a trough. The same goes for jet streaks.

The process of winds exiting a trough or a jet streak, known as divergence, creates a void in the upper atmosphere. Nature hates imbalance and will do just about anything to balance something that's out of whack. When winds diverge coming out of certain parts of the jet stream, air will rush up from lower altitudes to fill the void. This upward rush of air from the surface leaves lower air pressure at the surface, creating a low-pressure system that can trigger all sorts of nasty weather.

The jet stream is also one of those weather features that could feel the effects of climate change over the coming decades and centuries. Since these wind currents rely on sharp temperature gradients in order to form, a warmer atmosphere will lessen the temperature difference between north and south and possibly create weaker jet streams. A weaker jet stream could act more erratically, creating longer stretches of quiet weather—but also more frequent weather extremes.

How Coronavirus and 31 Other Infectious Diseases and Viruses Got Their Names

Rotavirus—from the Latin rota, for "wheel"—is named for the wheel-like appearance of its particles.
Rotavirus—from the Latin rota, for "wheel"—is named for the wheel-like appearance of its particles.
Dr_Microbe/iStock via Getty Images

As you may already know, the corona in coronavirus has no relation to a certain refreshing beer often served with a slice of lime. Corōna means “crown” in Latin—and Spanish and Italian, too—and virologists chose it in 1968 to describe the group of viruses characterized by crown-like spikes that protrude from their surfaces.

So how do other viruses and diseases get their names? Based on the infographic below, created by Adam Aleksic for his website, The Etymology Nerd, there isn’t just one way. Some, like the coronavirus, are named for how they look under a microscope. The rota in rotavirus, for example, which means “wheel” in Latin, reflects the virus’s wheel-like appearance when viewed beneath an electron microscope.

Others are named after the locations where they were discovered or studied. In 1947, scientists named a newly identified mosquito-borne virus after Uganda’s Zika Forest. In 1977, Yale researchers investigating a string of pediatric arthritis cases in the town of Lyme, Connecticut, started referring to the illness as “Lyme arthritis.” Later, the name was modified to “Lyme disease” when scientists realized patients were exhibiting other symptoms, too.

Still others are characterized by the symptoms they cause. People with tetanus—from the Greek tetanos, for “tension”—usually experience muscle stiffness, and the skin of yellow fever sufferers often takes on a yellow tint due to jaundice.

Find out the origins of malaria, measles, and more below. And follow The Etymology Nerd on Instagram for more fascinating etymological explanations.

etymology nerd infectious disease names infographic
Unsurprisingly, there's a lot of Latin in this infographic.

These 8 MasterClass Courses Will Get You Out of Your Netflix Funk

Chef Gordon Ramsay is just one of the professionals lending their knowledge to a MasterClass course.
Chef Gordon Ramsay is just one of the professionals lending their knowledge to a MasterClass course.
Franco Origlia/Getty Images

Although binge-watching Netflix is always a great way to kill a few hours, you might want to shake it up and do something a little more substantial with your free time. That’s where MasterClass comes in. A subscription package that features over 80 virtual courses in a wide range of subjects, MasterClass can help you explore exciting new subjects or improve your knowledge in an area you’re already familiar with. And all the classes are taught by highly recognizable experts in their fields, so you can be confident that the lessons you’re learning are solid (that Martin Scorsese probably knows a thing or two about filmmaking, after all).

The courses themselves are broken up into individual lessons that are only around 10 minutes long, so fitting them into your schedule is as easy as becoming a professional chess player (or it will be, once you’ve finished the course). MasterClass is priced at $15 a month for unlimited classes or at $90 per course, and you can sign up here.

So whether you want to become the next great young adult novelist or an expert bartender, MasterClass has something for everyone. Check out a few highlights from the course list.

1. Cooking with Gordon Ramsay

Gordon Ramsay, known for his sharp demeanor and high expectations in the kitchen, is an international chef, restaurateur, and television host who’s nothing short of legendary. And in his MasterClass series, he’ll teach you to become a legend, too. This series features the softer side of Ramsay, who teaches you knife techniques, seasoning tricks, kitchen layout, and much more. And, for anyone ready to level up, he also offers Cooking II: Restaurant Recipes in the Kitchen.

Sign up here.

2. Mixology with Lynnette Marrero & Ryan Chetiyawardana

If you’re ready to become an award-winning bartender—or just make a decent martini at home—look no further than this 17-lesson course with master mixologists Lynnette Marrero and Ryan Chetiyawardana. You’ll not only learn to craft the perfect cocktail, but also how to safely incorporate raw eggs into drinks, make complementary drink “seasonings,” and discover the best liquor to pair with food (who knew that whiskey and blue cheese were a match made in heaven?). A good drink has the power to bring people together, and after this course, you’ll be the go-to guru for any dinner party.

Sign up here.

3. Writing for Young Adults With R.L. Stine

After you’re through with R.L. Stine’s class on writing for young adults, you may just become the next sultan of the Scholastic Book Fair. According to his website, Stine has written over 330 books over the course of his career, and he’s provided thrills and chills to millions of readers with his beloved Goosebumps and Fear Street series. Now, he’ll teach you some of his favorite tricks of the trade, like why you should always start with the ending (so you can focus on fooling your reader for the entire book) and how writing from personal experience makes for a more sincere scare. This masterclass will help you perfect the art of scary storytelling and overcome any fears you might have about putting your own experiences on the page.

Sign up here.

4. Conservation with Dr. Jane Goodall

Dr. Jane Goodall is best known for her groundbreaking work with chimpanzees and gorillas, but she’s more than just a scientist—she’s an environmental activist and conservationist who wants to ensure that animal habitats are preserved for years to come. In this course, Dr. Goodall will share some of the conservation lessons she’s learned as a scientist, identify the central problems facing our planet today, and share effective methods for creating change. As she says, one of the best ways to confront environmental issues is by “telling stories, meeting with people, listening to them, and then finding a way to reach the heart.” This course will show you how.

Sign up here.

5. Chess with Garry Kasparov

Garry Kasparov, a chess grandmaster and world chess champion, will help you dust off your old chessboard and learn to play the game like it’s an art form. This 29-lesson class starts with the basics and gets more complex the further you get into the course. Using the tactics he’s curated throughout his career, Kasparov will show you how to approach chess with a strategist's mindset, including the basics of openings, interference plans, and endgames. This class even features other “students” so you’re not just studying the techniques, but seeing how they play out in real time, too.

Sign up here.

6. Comedy with Steve Martin

One of comedy’s greatest names—and one of film’s most beloved actors—is Steve Martin. The star of film classics such as Father of the Bride and Planes, Trains, and Automobiles, Martin will teach you how to find your comedic voice, develop your persona, and work a crowd so that you’ll never get booed off the stage. And he’ll share his comedic process, which involves more writing and editing than it does practicing in the mirror. This is the perfect class for anyone looking to practice their improv skills or sign up for their first open mic night.

Sign up here.

7. Space Exploration with Chris Hadfield

Make your childhood dreams come true with this course from retired astronaut Chris Hadfield, who’s flown two Space Shuttle missions and served as commander of the International Space Station during his 21 years as an astronaut. And in his course, he’ll teach you the intricacies of space exploration, from learning how rockets work to preparing your body for liftoff. Even if you're not planning on leaving the atmosphere (or your couch) anytime soon, this class teaches you what it's like to be an astronaut. And as Hadfield talks about his unique journey to the stars, there's the chance to learn plenty of life and career lessons that you can apply on Earth.

Sign up here.

8. Adventure Photography with Jimmy Chin

Even if your biggest adventure is going on a walk in your local park, award-winning adventure photographer Jimmy Chin (the face behind documentaries such as Free Solo and Meru) will still teach you how to turn your photographs into works of art. Chin’s class acts as part photography course and part adventure guide, teaching you every step from choosing the right location to editing the final product. You’ll learn how to plan shoots, pack the right gear, and even find clients if you want to go professional. Whether you want to make photography a career or just take the perfect photo of your dog at golden hour, this masterclass will get you feeling comfortable behind the camera and bring some more adventure into your everyday life.

Sign up here.

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