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.

Is There An International Standard Governing Scientific Naming Conventions?


Jelle Zijlstra:

There are lots of different systems of scientific names with different conventions or rules governing them: chemicals, genes, stars, archeological cultures, and so on. But the one I'm familiar with is the naming system for animals.

The modern naming system for animals derives from the works of the 18th-century Swedish naturalist Carl von Linné (Latinized to Carolus Linnaeus). Linnaeus introduced the system of binominal nomenclature, where animals have names composed of two parts, like Homo sapiens. Linnaeus wrote in Latin and most his names were of Latin origin, although a few were derived from Greek, like Rhinoceros for rhinos, or from other languages, like Sus babyrussa for the babirusa (from Malay).

Other people also started using Linnaeus's system, and a system of rules was developed and eventually codified into what is now called the International Code of Zoological Nomenclature (ICZN). In this case, therefore, there is indeed an international standard governing naming conventions. However, it does not put very strict requirements on the derivation of names: they are merely required to be in the Latin alphabet.

In practice a lot of well-known scientific names are derived from Greek. This is especially true for genus names: Tyrannosaurus, Macropus (kangaroos), Drosophila (fruit flies), Caenorhabditis (nematode worms), Peromyscus (deermice), and so on. Species names are more likely to be derived from Latin (e.g., T. rex, C. elegans, P. maniculatus, but Drosophila melanogaster is Greek again).

One interesting pattern I've noticed in mammals is that even when Linnaeus named the first genus in a group by a Latin name, usually most later names for related genera use Greek roots instead. For example, Linnaeus gave the name Mus to mice, and that is still the genus name for the house mouse, but most related genera use compounds of the Greek-derived root -mys (from μῦς), which also means "mouse." Similarly, bats for Linnaeus were Vespertilio, but there are many more compounds of the Greek root -nycteris (νυκτερίς); pigs are Sus, but compounds usually use Greek -choerus (χοῖρος) or -hys/-hyus (ὗς); weasels are Mustela but compounds usually use -gale or -galea (γαλέη); horses are Equus but compounds use -hippus (ἵππος).

This post originally appeared on Quora. Click here to view.

An Ice Age Wolf Head Was Found Perfectly Preserved in Siberian Permafrost


Don’t lose your head in Siberia, or it may be found preserved thousands of years later.

A group of mammoth tusk hunters in eastern Siberia recently found an Ice Age wolf’s head—minus its body—in the region’s permafrost. Almost perfectly preserved thanks to tens of thousands of years in ice, researchers dated the specimen to the Pleistocene Epoch—a period between 1.8 million and 11,700 years ago characterized by the Ice Age. The head measures just under 16 inches long, The Siberian Times reports, which is roughly the same size as a modern gray wolf’s.

Believed to be between 2 to 4 years old around the time of its death, the wolf was found with its fur, teeth, and soft tissue still intact. Scientists said the region’s permafrost, a layer of ground that remains permanently frozen, preserved the head like a steak in a freezer. Researchers have scanned the head with a CT scanner to reveal more of its anatomy for further study.

Tori Herridge, an evolutionary biologist at London’s Natural History Museum, witnessed the head’s discovery in August 2018. She performed carbon dating on the tissue and tweeted that it was about 32,000 years old.

The announcement of the discovery was made in early June to coincide with the opening of a new museum exhibit, "The Mammoth," at Tokyo’s Miraikan National Museum of Emerging Science and Innovation. The exhibit features more than 40 Pleistocene specimens—including a frozen horse and a mammoth's trunk—all in mint condition, thanks to the permafrost’s effects. (It's unclear if the wolf's head is included in the show.)

While it’s great to have a zoo’s worth of prehistoric beasts on display, scientists said the number of animals emerging from permafrost is increasing for all the wrong reasons. Albert Protopopov, director of the Academy of Sciences of the Republic of Sakha, told CNN that the warming climate is slowly but surely thawing the permafrost. The higher the temperature, the likelier that more prehistoric specimens will be found.

And with average temperatures rising around the world, we may find more long-extinct creatures rising from the ice.