figure 23.
When the surface jet streak is near the surface low pressure center, the surface pressure
rapidly decreases
The accelerations within the jet streak act to increase upward air motions. Because
upward motion is limited at the top of the troposphere, the air then moves outward (or
diverges) similar to the tropopause’s effect on convection at the ITCZ. The net result of
this upward motion in the vicinity of the jet streak is to decrease the mass of air
beneath it. This results in lower surface pressure. When the jet streak moves close to a
region with a developing surface cyclone, the effect is to further decrease pressure and
enhance the cyclonic circulation (figure 23).