Radar
RAdio Detection And Ranging
First Warn 5
Pinpoint Doppler Radar
At MBS
A Bit of History
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Has its roots in radio
In 1934, after a plane disrupted radio
communication, the idea for using pulses of
energy for target detection was born
Developed during WWII for military purposes
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Britain's initial goal was a “Death Ray”
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Used to track warships and airplanes
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Radar operators annoyed at “weather always getting in the
way” Rain often obstructed the detection of advancing enemy
attackers
First weather radar developed in England and tracked a rain
shower on Feb 20th, 1941
Radar technology has greatly advanced since then, mainly due
to high-speed computers
How does the radar work?
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Receives Weather information based on Returned
Energy.
Radar emits a burst of energy (Green) and if it strikes
an object (Blue) The energy is scattered in all
directions. A small fraction is directed back toward the
radar.
How does the radar work?
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Computers analyze the strength of the returned
pulse, the time it takes to travel to the object
back and the phases shift of the pulse. We can
see where something is.
The Doppler Radar
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The Doppler Effect: Change in the frequency of
waves because of motion.
Most people can recognize the Doppler Effect as
the sound of a passing car.
The Doppler Radar
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As a car passes the pitch of the horn changes from High
to Low. As the car approaches the sound waves are
compressed. As it moves away they stretch.
Compressed waves produce a higher pitch, stretched
waves produce lower pitch.
The Doppler Radar
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Doppler Radar uses this concept
The computer can tell if the object is
moving towards or away from the radar
and how fast
it is moving
Rain that isn’t Rain
The Radar is so accurate that is detects all
sorts of things such as bugs and birds.
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Echoes from migrating birds regularly appear
during nighttime between late Feb to late May.
Insects are sometimes
apparent during July
and August.
Rain that isn’t Rain
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Ground Clutter
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Portion of radar beam hits buildings, trees, hills
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Also can be due to dust, aerosols in the air near the radar
Gives false indication that precipitation is present.
Rain that isn’t Rain
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Virga
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Radar detects precipitation occurring at upper levels,
but not making it to the ground
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Precipitation quickly evaporates in dry air below cloud
How often are the images updated?
Some types of radar update every 5 to 10
minutes. But the First Warn 5 Radar at MBS
is a live radar that updates continuously!
Intensity usually depicted on
computer image by scaling
various colors
• Reds/purples = heavier precipitation
• Yellow = moderate
• Blues/greens = lighter precipitation
Radar During Storms
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We switch to a different type of Radar that
shows wind velocity
 Red = Moving away from Radar
 Green = Moving toward Radar
Radar During Storms
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What does it mean when Red and Greens
are right next to each other?
Radar During Storms
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A hook echo is a clue to the Meteorologist that a
supercell has the potential to produce a tornado.
Radar During Storms
October 18th 2007
Radar During Storms
Black Lake Tornado
•EF1 Tornado Classification
•Winds up to 94 mph
• It destroyed a barn just north of
M-68, leaving sporadic damage
around Black Lake.