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Blowin' in the Wind, Issue #058 Basic Jet Stream Info. - September 1, 2008
August 27, 2008
Introductory Jet Stream Info
Iíve got some elementary jet stream info for you. Remember what jet streams are? Fast moving narrow air currents that flow from the west to the east.
Meteorologists find them about seven to eight miles above the earth, or 36,000 feet, near the tropopause, which separates the upper troposphere from the stratosphere. Research of jet stream info shows that they blow in a transition zone of maximum temperatures between air masses.
The strongest jet streams are the called a polar jet streams. The strength of the stream depends on the strength of the surface temperature gradient below it, and in a subtropical jet stream the surface temperatures do not vary as much as they do in polar regions.
Each Jet Stream PathThere are two major jet streams in the world, one surrounding each pole. There are also two minor jet streams above subtropical air and they are located closer to the equator than the poles, and they circle the globe at middle and polar latitudes in each hemisphere.
The two Northern Hemisphere jet streams can usually be found somewhere around latitude 20 degrees and 50 degrees north, during the winter, with wind speeds averaging 35 miles per hour.
During the summer they push northward to latitudes of 30 degrees and 70 degrees north, with wind speeds averaging 75 miles per hour. jet stream info has recorded winds over 200 miles per hour.
However, wind speed has to be higher than 69 miles per hour in order to call it a jet stream. Jet streams do not move in a straight line, but flows in a westerly wave like formation.
What's Up?There are also weaker jet streams that form in the northern skies, high in the Stratosphere, during the polar winter. These weak Polar Night jet streams, and the weak Tropical Easterly Jet stream over Africa, Southeast Asia, and India during the summer, vary in time and position depending on the seasons and the shape of the landmass.
Thermal wind doesnít tell us why winds are organized into jet streams, but there are two factors to take into consideration. One is the development of cyclonic disturbances that form a front, an air mass boundary.
The polar front jet stream has cyclonic small wind disturbances in a large wind flow that can produce turbulent conditions called eddies. We see eddies of this sort when warmer air lies poleward of warmer air. Analogously, in an oceanic circulation an eddy forms when a movement of water forms where currents meet obstructions.
Jet streams are an integral part of our everyday lives. They serve as a prime indicator of how the weather in our area is going to change. With jet streams and other data, meteorologists determine if it is going to be hot, cold, sunny, or cold.
The next time you watch the weather on TV, keep your eyes on the way the jet stream in your area is moving and what large scale affects it is predicted to cause.
Hereís a bit of interplanetary jet stream info. Jet streams do not happen just here on our planet, but each planet has it own set of jet streams. What can be quite obvious from space photos? The atmosphere of Jupiter has multiple jet streams, forming in the same banded structure as the Earth's jet streams.
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