Jet Streams...how do they form and why are they so fast?

Question

Jet Streams...how do they form and why are they so fast?

Answer 1

This is a fairly complicated subject, but the basics in which the jet is formed is related to temperature and pressure gradients along a horizontal and vertical plane.

The jets are always located at breaks in the troposphere, where there also is the greatest thermal gradient.  It divides upper level airmasses of different temperature.  The convergence and divergence occuring around the breaks in the troposphere create an air flow which is magnified.

Below is a good tutorial on the origin of jet streams.

Answer 2

Jet streams are fast flowing, relatively narrow air currents found at the tropopause, the transition between the troposphere (where temperature decreases with height) and the stratosphere (where temperature increases with height),[1] and are located at 10-15 kilometers above the surface of the Earth. They form near boundaries of adjacent air masses with significant differences in temperature, such as the polar region and the warmer air to the south.[2] The path of the jet typically has a meandering shape, and these meanders known as Rossby waves. Rossby waves propagate westward with respect to the flow in which they are embedded, which translates to a slower eastward migration across the globe than smaller scale short wave troughs. The major jet streams are westerly winds (flowing west to east) in the Northern Hemisphere.

During the summer, low-level easterly jets can form in tropical regions. A southerly low level jet in the Great Plains of North America helps fuel overnight thunderstorm activity, normally in the form of mesoscale convective systems. A similar northerly low-level jet can form across Australia, instigated by cut-off lows which develop across southwest portions of the country.

Meteorologists use the location of the jet stream as an aid in weather forecasting. The main commercial use of the jet stream is during airline travel, as flying long distances along the jet stream can cut hours off a long distance trip. One type of clear-air turbulence is found in the jet stream's vicinity, which can be a hazard to aircraft. One future benefit of the jet stream could be to augment power generation within the next 10 to 20 years, if technological hurdles can be overcome. HOPE IT HELPED