SECTION VIII
CORRECTION AND CONVERSION TABLES
29.
General
When using the single base and leapfrog methods of altimetry, corrections are required for air temperature,
relative humidity, altitude, and latitude. This section provides instructions on the use of the tables that are required to
make the above mentioned corrections. These tables are supplied with the altimeter on 4 x 6 inch plastic cards, stored in
the cover. An individual instrument temperature correction graph is hinged in the cover. In addition, this section provides
for converting inches pressure to meters altitude when calibrating the altimeter with a mercurial barometer.
30. Table I, Air Temperature and Relative Humidity Correction
Table I combines the correction factors for air temperature and relative humidity. The wet and dry bulb temperatures are
obtained with the sling psychrometer. Knowing the wet and dry bulb temperatures the correction factor can be determined
from the table. For example, assume altimeter A reads 900 meters and B 1,100 meters (both corrected for instrument
calibration), average dry bulb reading 800 F. and average wet bulb reading 600 F. Find 80 along dry bulb temperature
column, follow across to 60 of wet bulb temperature column. Read correction factor 1.063. Corrected altitude difference =
(1,100-900) (1.063) = 212.6
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