What is the jet stream and how does it come about?

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Offline chris

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What is the jet stream, how does this moving air mass come about and what controls its location around the Earth? How, if at all, does it influence weather patterns around the planet?
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Offline Colin2B

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Re: What is the jet stream and how does it come about?
« Reply #1 on: 17/03/2016 22:40:52 »
The jet stream is formed in the same way as high and low pressure areas, due to temperature differences.
Warm air, less dense, cold air more dense. These try to equalise and so air flows creating wind. The greater the temperature difference  and the deeper the air masses the greater the pressure difference eg at altitude, the faster the wind. These winds would flow directly from high to low pressure on a stationary earth but Coriolis effect causes the wind to flow around the air masses towards the right in Northern hemisphere.
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Offline Tim the Plumber

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Re: What is the jet stream and how does it come about?
« Reply #2 on: 18/03/2016 22:11:48 »
As air is heated most at the equator it rises, causing the water to drop out of it, rain.

When it gets to the top of the circulation system it moves North and South. It then comes back down as it has cooled.

Because it left the ground with the angular velocity of the ground at the equator and it drops back down 40 North and South it has a velocity faster than the ground it is dropping over. The ground's distance from the axis of rotation being less the further away from the equator you are.

When the air that is about to drop is at high altitude and away from the equator it has a high velocity relative to the ground below it. This is essentially what the jet stream is.

That's a little simplified but ....