Training Guide in Surface Weather Observations - Multiple Choices

. If an altimeter setting indicator is not used:
1. Obtain the station pressure from the precision aneroid barometer,
microbarograph, mercurial barometer, or Digiquartz standard.
2. Using the above station pressure, determine the corresponding altimeter
setting by use of the pressure reduction calculator or from altimeter setting
tables.
4. Sea-level Pressure:
a. If a pressure reduction calculator is available:
1. Determine the station pressure to the nearest 0.005 inch or 0.1 hPa.
2. Compute the mean of the current temperature and the temperature 12 hours
previously.
3. Select the “r” value from the table furnished to your station that corresponds to
the mean temperature computed above.
4. Following instructions printed on the calculator, use the “r” value selected
above and the station pressure, as determined in (1) above, to calculate the
sea-level pressure to the nearest 0.1 hPa.
b. If a pressure reduction computer is not available:
1. Determine the station pressure to the nearest 0.01 inch or 0.1 hPa.
2. Compute the mean of the current temperature and the temperature 12 hours
previously.
3. Using the station pressure and the mean temperature found above, determine
the sea-level pressure to the nearest 0.1 hPa from reduction tables. (If the
reduction tables are in inches, use conversion tables to obtain hectopascals.)
B. When evaluation of meteorological data has been completed, enter the following nonmeteorological
data on MF1M-10:
1. Type of observation (column 1)
2. Time of the observation (column 2)
3. Your initials (column 15)
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