Metro-01
Review of Basic Meteorological Principles
E. Jet stream 1.1.1.3.5
Fig 9: Polar and
1. Forms in tropopause - the boundary between the troposphere and
Subtropical Jet Streams
the stratosphere
a. Height varies from 65,000 ft at the equator to 20,000 ft or less
at the poles
b. Tropopause drops by steps between arctic and polar airmasses
and another drop between the polar and tropical airmasses
c.
Between the polar and arctic "layers," the Polar Front Jet
Stream forms; between the polar and tropical "layers," the
Subtropical Jet Stream is formed
(1) Polar jet stream is the primary North American jet stream
(2) Subtropical jet stream found between 25 degrees and
30 degrees North latitude
NOTE: From the Hawaiian Islands eastward to southern
Florida, the Subtropical Jet Stream sometimes drifts north
and merges with the Polar Jet Stream.
2. Jet stream characteristics
Fig 10: Jet Stream
Profile
a. They are a narrow, shallow band of strong westerly winds of
50 kts or more
(1) Strength of the jet stream is stronger in the winter than in
the summer
(2) Wind speeds up to 300 kts have been recorded
(a) Summer: average 75-100 kts
(b) Winter: average 150-225 kts
b. Jet streams wander vertically and horizontally around the
Fig 11: Polar Jet
hemisphere in wave-like patterns
Stream
(1) Jet streams in northern hemisphere are matched in
southern hemisphere
(2) They are stronger in some areas than others
(3) They rarely encircle entire globe as a continuous river of
wind
(a) Most frequently found in 1,000- to 3,000-mile
segments
(7-97) Original
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