Jet Streams

[Jane Louise]

Hi all can anyone explain to me what Jet streams are?

Thanks

Edited July 15, 2006 by missdaney

[AtlanticFlamethrower]

This is a basic introduction - I don't know enough myself to say anything advanced, but simple stuff is easy to find.

A Jet stream is a belt of fast-moving (hurricane++ speed) air at high altitudes that are found between polar (cold) and tropical (hot) air masses in the northern and southern hemispheres.

Basically the way the hot air from the equator and the cold from the poles sort out the temperature conflict is with a big fight all the way around the earth along the boundary of the air masses - Face-Off villain and hero shooting at each other through the glass style, always going west-east in both hemispheres, due to the Coriolis effect (the rotation of the Earth).

Jet streams are so-called because on weather charts they look like streams. Passenger jets often catch a lift on them, using them as a conveyor belt to get somewhere faster on less fuel (this is only possible in the west to east direction).

Like a skipping rope being flicked from one end the jet stream meanders up and down - the bends also go in a west-east direction. This can help forecasters predict what weather is coming and where weather is going. Eg. if the Jet stream bends up from the Atlantic and goes north over Britain we get in the hot air.

You can see in the above image of the Jet stream today, with that big streak of red. It was over 30C in much of UK. In march this year the Jet stream was much lower, nearer Spain, and it was cold in Europe.

The bends of the Jet stream move slower than the winds in them, and you can see an example of the wind speed in the above image.

The exact position of the jet streams fluctuates and is affected by the seasons - in summer the hot air beats the cold on average further northwards and in the winter the cold fights back, bringing colder air south more often.

A look at the northern hemisphere today.

Here's a link to a live Jet stream animation.

Edited July 18, 2006 by AtlanticFlamethrower

[Jane Louise]

Thanks very much. interesting.