Jet Stream Geography

Dave Thurlow, Host

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The whole atmosphere is a bit like a river of air that circles around the planet from west to east, the jet stream is just the fastest part of this river. Winds of over 330 kilometers per hour, nearly 200 miles per hour, are found in the jet stream. The polar jet stream as it's called is usually found about half way between the equator and the North Pole, separating the cold air from the warm. Television weathercasts will sometimes show the position of this jet stream. It will be a curved line that more or less divides North America in half, north to south.

The jet stream itself indicates the general movement of the atmosphere, sometimes straight west to east, sometimes curving up and down like a roller coaster. The more it curves, the more weather you have, and what causes the curves is, in part, explained by geography.

For over a billion years continents have been floating around the planet like bumper cars. The present configuration has two big land masses and two big oceans in the Northern Hemisphere, with little land masses and a whole lot of ocean south of the equator. The large difference between the temperature of land and water, especially in the winter, spring and fall, causes pressure changes in the atmosphere above, and helps make the jet stream snake it's way across the middle part of North America and the rest of northern hemisphere.

The Weather Notebook is made possible by a grant from The National Science Foundation. Additional support comes from Subaru, maker of the all weather Legacy. Subaru, the beauty of all wheel drive.

Related Links

Earth/Atmosphere FAQs - Dr. Sten Odenwald

Origin of Earth's Oceans and Atmosphere - Carleton University

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Soul of the Sky - "Exploring the human side of weather"  NOW AVAILABLE Compiled and edited by: Dave Thurlow & Ralph Adler. North Conway: Mount Washington Observatory, 1999. Paperback, 150 pages.   Soul of the Sky is a different kind of weather book. It's not preoccupied with charting fronts, defining what an isobar is, or trying to get you to memorize the conversion formula from degrees Centigrade to degrees Fahrenheit. Instead, it's a collection that illustrates how the weather can inspire and terrify, connect us and urge us on to new adventures, and invite us to gain a deeper appreciation of how weather and climate affect our everyday lives.

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