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Inside the Jet Stream
by Rick Groleau

For the very few of us who will ever pilot a jet at high altitude, deciding whether or not to fly in the fast-moving, eastward-blowing jet stream will be fairly easy. If you're flying west, you want to stay out of it. If you're flying east, you want to get in it.

So what is the jet stream? And why is it there?

Perhaps your image of the jet stream comes from maps broadcast during the weather portion of your local news. You know the kind: the ones where, if you live in the U.S., there's a long, fat, solid arrow that enters in from the northwest corner of the country, dips down to the lower Midwest, moves up over the Northeast, and then continues out over the Atlantic Ocean. ("The jet stream will bring such and such weather our way," the forecaster might say.) Well, in actuality, the jet stream is a complex phenomenon involving the interplay between many variables. Here is a simplified introduction...

Giving Rise to the Jet Stream (154k)
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What generates the jet stream? Why does it flow from west to east? Find out here.

Giving Rise to the Jet Stream (non-Flash version)
A Five-Day View of the Jet Stream (435k)
The jet stream, rather than being a nicely contained river of air, meanders around the globe in a largely unpredictable way. For a realistic depiction of how the jet stream flows, check out this animation.
Jet Stream FAQ
Here are some answers to frequently asked questions about the jet stream, previously published on NOVA's "Balloon Race" Web site.
Glossary
Terms used in the "Giving Rise to the Jet Stream" feature