Pressure Gradient at Jet Stream

[Michael Wilkinson]

I’d like to check to see if I properly understand the Jet Stream. The attached graphic is a cross section of the vertical atmosphere with the winds flowing into the page (towards the East).

The facts as I think they are
- The Jet Stream exists because the atmosphere is colder to the north, and therefore more dense, making pressure heights in the north lower.
- There is a large pressure gradient at the Jet Stream (due to lower heights to the north).
- The Jet Stream acts as a divider between cold air and warm air.
- The atmosphere above the Jet Stream becomes more stable with height due to the Stratosphere’s property of an increase in temperature with height. This increase in temperature occurs at a lower altitude over the North than it does to South (due to the Troposphere being thicker to the South). This means that the pressure gradient between North and South becomes less above the altitude at which the North stops decreasing in temperature with height. Therefore, the winds start to weaken above that altitude. This leaves the Jet Stream as the place where the geostrophic winds are greatest relative to the winds both above it and below it.

 

[Jeff Duda]

Yes, your understanding is very good, and those paraphrased statements are all correct in a broad sense. Just keep in mind that those statements are meant to apply at higher levels of the troposphere and do not necessarily correlate 100% with what happens near the ground. In the lower troposphere, fronts formally separate air masses.