GIANNETTA WEATHER

Bath, Pa,



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**The Jet Stream**

 





Meteorology              Charles A. Giannetta
                         Meteorologist - Professor 
 
"Jet Streams & Weather"


 
   The jet streams are belts of high speed winds occurring at about 5 to 10 miles
above the earth and may occur at higher or lower levels. These winds blow at 
speeds of 150 to 300 miles per hour. Speeds to 400 mph have been reported.

   The streams of high winds blow from west to east about the Northern Hemisphere.
They may be 2,000 to 3,000 miles long. 300 to 400 miles wide and 10,000 to 20,000
feet thick as they serpentine around the globe.

   The jet streams were first encountered by military aircraft during 
World War II, but prior to that they were suspected to exist due to the 
observations of fast moving high cirrus clouds. Pilots flying west fly to avoid 
them, when flying east will try to fly along with the jet stream to get an added
boost of speed.

   The jet stream moves from side to side around the earth wandering north and 
south depending on the season. In winter in the Northern Hemisphere they move
south to blow hardest at about 30 to 35 degrees north latitude or over the 
United States area. In summertime the core of the jet stream lies about 40 to 
45 degrees north latitude. Similar jet stream movements also appear in the 
Southern Hemisphere.

   Mush has been learned about the jet streams, but an exact explanation for 
their origin is still lacking. One theory is that the jet streams may form by 
coming together of larger streams of equatorial and polar air masses at great
heights.

   When these cold and warm air masses are side by side, there is a resulting
difference of pressure and temperature and may cause a strong circulation which
becomes  a jet. In North America, the North Atlantic and Europe, observations
have been sufficient to detect jets and forecast their behavior.

   The jet streams are closely related to the polar front which separates tropical
and polar air masses at about 60 degrees north latitude. The polar front is a 
continuous breeder of weather of the temperate zones.

   The jet stream seems to play an important part in the formation, steering and
intensifying of weather phenomena such as cyclones, hurricane tracks and abnormal
weather spells.




"Jet Winds"

1...Jet winds are caused by differences in temperature and or differences in pressure.
2...Jet Winds usually occur at heights of 30,000 to 60,000 feet on average.
3...Jet winds were first encountered by high flying aircraft during World War II.
4...Jet winds occur at speeds of 30 mph and can reach speeds of 400 mph.
5...The jet winds usually move form west to east, however, they do move north and south.
6...The jet winds in the summer time are usually located at about 45 degrees N. Lat.
7...During the winter months, the jet winds move as far south as Florida.
8...The jet winds maybe 500 to 3,000 miles long. 50 to 500 miles wide. ....5,000 to to 30,000 ft. in height.
9...The jet winds mover around the hemisphere in a "Snake-Like" maner.
10..The jet winds are also know as the Jet Stream.

"Copyright" 1998-2014 Charles A. Giannetta



The jet streams are belts of high speed winds occurring at about five to ten miles above the earth and occur at higher or lower levels. These winds move at speeds of up to 150 to 300 miles per hour. Speeds of 400 mph are not uncommon.

These areas of high winds may be 2,000 to 3,000 miles long, 300 to 400 miles wide, as they move from west to east in the Northern Hemisphere. Similar jet streams occur in the Southern Hemisphere, however, their movement is from east to west.

Pilots flying military aircraft during World War II first flew into these jet streams. Now, when pilots flying in the Northern Hemisphere, fly west they try to avoid them, however, when flying east they try to fly along with the jet stream.


As these jet streams move around the globe, they meander side to side.

In the Northern Hemisphere, there are two areas of jet winds. One area occurs at about 30 to 35 degs. N. Lat. and another at about 40 to 45 degs. N. Lat.

During the summer months, an area of jet wind is usually located over the United States/Canadian border. In the winter this jet stream moves south to over the southern United states. This jet stream is closely related to the arctic front which separates tropical and polar air masses. The polar front is a constant breeder of weather in the temperature zones in which the United States is located.

The jet stream plays an important roll in the steering and formation of weather such as, cyclones, hurricane tracks and abnormal weather conditions.

Choose here to view graphic of Jet Winds


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© 1998 Charles A. Giannetta

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