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Author Topic: Can someone explain exactly why and how a Jet Strean works?  (Read 1809 times)

Offline Joe L. Ogan

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I find the explanation of how or why a Jet stream works a little confusing.  I know it is caused by a high pressure area and a low pressure area coming together.  There is a natural tendency for  the high pressure to try to go to the low pressure.  In the northern hemisphere, the high pressure area rotates clockwise and the low pressure area rotates counter clockwise.  The rotation of the earth is toward the east.   The rotation of the earth has something to do with the jet stream, but I can not quite understand how this works.  The explanation is far from satisfactory to me.  Can someone please explain just how or why this works?  Thanks for comments.  Joe L. Ogan


 

Offline Joe L. Ogan

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I have thought about this a great deal and I think the reason is because the earth rotates so much faster at the equater than it does further north.  Since the low pressure area travels toward the north and the high pressure travels toward the south the rotation of the earth creates a partial vacumn between the two pressure areas which bends the jet stream  toward the east.  The partial vacumn causes the jet stream to increase speed in its' attempt to reach the low pressure area.  Thanks for comments.  Joe L. Ogan
 

Offline yor_on

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I'm not sure Joe? Maybe you're thinking about shear forces? There are clearly wind shears  associated with Jet streams, but the main reason why they have so clear outlines is their momentum. Instead of jet streams think of it as drawing three footballs. One drawn just near the top of your globe (which is the pole), the second, following a straight line down, placed at the middle of the globe where the earth bulges out the most. The third, still following that straight line, placed near the bottom of your globe, near the opposite pole.

If you put one football on the top of your globe it would just spin round as you rotated that globe, right :)

But the football you put at the middle, where Earth bulges out the most from its axis, that one would start to move rather fast. It's like being on a carousel, if you're standing at the exact center of it, the axis, furthest in so to speak, you just spin around, but the closer you get to the outer edge, the rim of that carousel, the faster you will find yourself moving around and the more momentum you will have.

And that is your momentum, and those three footballs momentum too. The one near the top and the one near the bottom don't get so much momentum, but the one in the middle, the equator where earth bulges out the most, will get a lot. That football will also have the longest 'distance' to cover, and  spinning the globe you can see that it does in the same amount of time as the two you placed near the top and bottom. This Noaa explanation describes it a little differently, but they mean the same thing as I, hopefully :)

The Jet Stream.
 

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