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The Jet Stream

The Jet Stream

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I was taught in flight school that the Jet Stream is a separation between the troposphere and the tropopause. Or rather, it occurs at that boundary and is caused by the movement of the air in the troposphere as compared to the relatively static air of the tropopause.

During High Pressure when the tropopause is closer to the earth then of course the jetstream is closer to the earth.

I'm having a little trouble understanding how that works because as explained, if it is part of the boundary then it seems like it would have to cover the entire planet.

What makes the jetstream run the route it does? And why is it only at a certain area or stream? I'm just having trouble visualizing a model.

Keith H.


Since I do not specialize in aviation, that's definitely a different way of looking at the jet, but practical for what you do if you fly. The jet does hang out at the tropopause layer. If you look at the layers of the atmosphere, the temperature at the tropopause actually begins to increase. This tropopause layer is above the tropopshere, the layer where we live and where all weather happens. In our layer, the temperature decreases with height. As we transition into a layer (in the vertical above our heads) when the temperature increases, we form a gradient or difference in temperature. This helps to accelerate the winds. Other surface temperature gradients help to make a pressure difference aloft, this too helps create the strong band of wind.

Now the tropopause can rise and sink during the year so the jet stream will be higher or lower depending on the time of the year. During cold winter months, the jet stream will be lower since cold air is more dense. When it's warmer, the jet stream will be a little higher up.

You say then, does the jet go all the way around the planet? Absolutely! It forms ridges and troughs all the way around the globe. It doesn't magically stop anywhere, imagine if it did, then we'd have nothing to move any surface weather at that spot!

The jet stream helps to divide air masses, cold air from very warm air. These temperature differences help to create it and move it around the globe. Winds in the jet stream are easily over 130 mph and can go up to 300 mph!

Some helpful links on the right side of this page will also assist in your venture to learn more on the Jet.

Answered by KSL Meteorologist Dina Freedman.

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