Name: What Is The Jet Stream & How Fast Does It Go?
Uploaded: 2015-08-03T05:15:54.000Z
Duration: 2 min 54 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Basic passive voice

This episode of DNews is brought to you by Squarespace.

Transition words & phrases

Surfers think catching a gnarly wave is radical? Thanks to some science we can ride air currents

Adverbs of degree

at almost the speed of sound with 200 ton surfboards in the sky. How’s that for radical?

Hey silver surfers, Julian here for DNews. British airways flight 114 recently made a

transatlantic crossing almost an hour quicker than usual, and was clocking ground speeds

of 745 miles per hour, or nearly 1,200 kph.

It’s been making news because that is a frankly ludicrous speed, considering the speed

of sound at that altitude is somewhere around 1100 kph. But when you take into account the

airspeed, that is the speed the airplane is traveling through the air around it, instead

of the groundspeed it didn’t actually break the sound barrier, which is a good thing because

the Boeing 777 really wasn’t designed for that.

Fortunately for everyone stuck in coach, the aircraft was riding a particularly ferocious

jet stream that was at times over 320 kilometers per hour. But why do we have jet streams?

First of all jet streams are not unique to earth. We’ve observed them on Jupiter and

Saturn. Here on Earth jet streams form in the troposphere, the lowest atmospheric level,

and there can be many that swirl and flow and join and split. Most of them head from

west to east, so if you’ve flown from North America to Europe, you’ve probably noticed

your flight is shorter in that direction. The one you and flight 114 cruised on is the

northern hemisphere’s polar jet stream. The polar jet streams are from 7 to 12 kilometer

up, but each hemisphere also has weaker subtropical jet streams that are 10 to 16 kilometers up.

Jet streams form at boundary layers between warm air and cold air. The higher pressure

cold air pushes into the low pressure area, and in the winter the pressure differences

are greater so you get stronger winds. But the wind doesn’t just move in a straight

line from pole to tropics because of the coriolis effect. Basically the planet spinning underneath

the moving air deflects it east. Higher in the troposphere there’s less friction so

these winds can go unbroken for thousands of miles and voila, jet steam. Throw in modern

air travel and if you’re lucky you can get where you want to go at almost the speed of

Switching gears for a second, we'd like to thank Squarespace for this episode of DNews.

Squarespace recently launched the latest version of their platform, Squarespace Seven, which

has a completely redesigned interface, integrations with Getty Images and Google Apps, new templates,

and an incredible feature called Cover Pages. Try the new Squarespace, at Squarespace.com/dnews,

and enter offer code DNews at checkout to get 10% off.

If you don’t think I’ve gone basic enough to explain why there are jet streams, Trace

explains air itself here. Also, you were probably one of those kids who kept asking why all

So planning a world trip, would you head westerly to ride the current, or east to west to feel

like a time traveler? Tough call, but me, I like cruising into the sunset for hours.

Let us know in the comments and I’ll see you next time on DNews.