Weather Maps

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Much information is needed to interpret what is
happening with the atmosphere.
Need to condense this information in a small space
Need to show the geographic characteristics of
this data
Weather maps can both display this data and
summarize the patterns
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Station Model Allows the data to be plotted in a
condensed and usable format
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Location of the station on the map.
The name of the location or airport abbreviation
might be given nearby.
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Temperature information in degrees Fahrenheit.
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Dew Point Temperature in degrees Fahrenheit.
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Wind direction A staff is rotated around the
station.
Remember, winds are identified as the direction
FROM which they come. This would be a west
northwest wind or about 290º.
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Wind Speed Attached to the staff are symbols for
speed.
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The coding for the wind speed symbols can be
generalized as
half staff about 5 knots
full staff about 10 knots
these are additive for the total amounts three
full staffs30 knots
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Current Barometric Pressure
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Barometric Pressure is VERY important!
average barometric pressure at sea level is
1013.25 mb.
current barometric pressure is reported to the
nearest TENTH
BUT, they dont want to waste space
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average barometric pressure at sea level is
1013.25 mb.
barometric pressure varies around this value
about 30 1043
somewhat higher
1013.3
somewhat lower
- about 30 983
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average barometric pressure at sea level is
1013.25 mb.
barometric pressure varies around this value
they do not PRINT the beginning number or numbers
1013.3
---- 13.3
they, also, do not PRINT the decimal point, but
report to the nearest TENTH
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From the three numbers, you must INTERPRET
whether the preceding value is 10 or 9 Which
would make the value most realistic?
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add the decimal point and then consider which, a
10 or a 9 places the value NEAREST to the average
pressure of 1013.25 mb.
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(1013.3)
What is the pressure?
084
08.4
1008.4
962
96.2
996.2
281
28.1
1028.1
987.5
875
87.5
322
32.2
1032.2
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Not only is the pressure itself important, but so
is the way the pressure has been changing. So,
more information may be given and must be coded.
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How has the barometer been changing?
it is higher now than in the past - it is lower
now than in the past
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How much the pressure has changed
the amount of change in the past three
hours again, reported in TENTHS without the
decimal
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What has the pressure been doing? Shown
diagrammatically
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Total amount of cloud
graphic depiction of percentage of the sky
covered by clouds
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about 60
no clouds
about 10
about 75
about 25
about 80
completely overcast
about 40
sky obscured
about 50
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Symbol positions to identify the cloud types
Cloud types tell much about the weather
conditions. The cloud types are identified by
symbols, and classed as low, middle, and high
clouds.
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How much of the sky is covered by low and middle
cloud cover?
low or middle cloud cover
What amount, in tenths, of the sky is covered by
low or middle clouds. This is a coded number
with the percentage close to the printed number.
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What is the present weather?
low or middle cloud cover
The current weather is very important. A
detailed set of symbols provides weather
descriptions.
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Samples of present weather symbols.
rain
fog

snow
haze
slight rain showers
thunderstorm
,
drizzle
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ice or snow pellets
lightning
cloud development not observed
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100 different symbols provide details about the
PRESENT WEATHER.
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The visibility is especially important for pilots.
low or middle cloud cover
Visibility is given in miles and fractions
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The past weather uses symbols.
,

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Time precipitation began or ended
Coded for how many hours ago the precipitation
began or ended. Again, the code is close to the
number of hours.
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The amount of precipitation
amount
Amount of precipitation is plotted in inches to
the nearest hundredth of an inch.