     Mount Washington Observatory  National Oceanic and Atmospheric Administration  Subaru of America  National Science Foundation |
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| Jet Streams Galore |  Dave Thurlow, Host |
I'm Dave Thurlow for the Mount Washington Observatory and this is The Weather Notebook. If there's one scapegoat that TV weatherpeople love, it's the jet stream. But there isn't just one jet stream, there is a whole family of jet streams for meteorologists to blame things on.
There are three main jet streams circling the globe in each hemisphere, about three to seven miles above the earth. Each hemisphere -- north and south -- has a polar jet stream and a subtropical jet stream. In between the latitude of each of these jets is the temperate zone of the midlatitudes. In the wintertime, the polar jet sags south across the U.S., reflecting the southern extent of the cold air below. But in summer, the polar jet retreats in to Canada and the subtropical jet arcs north to replace it, helping to trigger warm weather, violent thunderstorms and heavy rain.
In the central U.S., there's still another player in this weather drama called the low-level jet stream. It's an intermittent but powerful conveyor belt of moisture that streams from the Gulf of Mexico up through the Midwest. This low-level jet is poised only about a mile above the ground, but it can race northward at close to 100 miles an hour, especially at night. The low-level jet was particularly active in the summer of 1993, when it helped to bring buckets of unwanted Gulf moisture to the flood-ravaged Mississippi. So, go ahead, if you have bad weather, blame it on one of the jet streams, you'll probably be right.
Funding for The Weather Notebook is provided by The National Science Foundation. Our show is underwritten by Subaru, maker of the all Weather Legacy. Subaru -- the beauty of All-Wheel Drive.
Related Links
How the jet stream influences weather - USA Today
How nighttime, low-level jet streams form - USA Today
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Soul of the Sky - "Exploring the human side of weather"
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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