PREPARATION OF CHARTS IBO= Mil 
Whenever two temperature values occur atthe same pressure 
(as when the balloon is forced down and reascends), both values 
will be plotted on the adiabatic chart ifthe difference is 1°C or 
more. The temperature curve for the first ascent will end, 
and for the last ascent resume, at their corresponding tem- 
peratures. Use the colder temperature for purposes of trans- 
mission and tabulation. If the difference is lessthan 1°C, the 
colder temperature will be plotted and the warmer value ig- 
nored. 
4.4 Relative Humidity. On each significant level plot the corresponding 
value of relative humidity, and connect each successive point with a 
straight line. Enter ''M" on significant levels at the 50 percent line to 
indicate missing humidity. No entry will be made when the temperature 
is colder than -40.0°C. 
a. 
= i= (99) 
Neither dashed nor solid lines will be drawn through strata 
more than 50 mb. in extent whose dataare classified as mis- 
sing. When the surface relative humidity is not evaluated be- 
cause the dry-bulb temperature is colder than - 35°F (-37.2°C), 
the relative humidity will be regarded as missing from the 
surface to the first usable humidity contact anda line will not 
be drawn regardless of the thickness of this stratum. 
A solid line will be drawn through missing RH data 50 mb or 
less in extent whenever the missing portion is ignored (see 
DBAS iosc e))r 
Whenever two values of relative humidity occur at the same 
pressure (as when the balloon is forced down and reascends), 
both values will be plotted onthe adiabatic chart. The relative 
humidity curve for the first ascent will end, and for the last 
ascent resume, at their respect values. The value to be used 
in all computations, etc., pertaining to this level, will be the 
value corresponding to the temperature selected in accordance 
with §B5-4.3 (d). 
When the relative humidity curve terminates at the highest 
level on WBAN-31A, this single value will notbe replotted on 
WBAN-31B. 
The completed relative humidity curve will be labeled ''RH"' 
at the top and bottom of the curve on each chart. Where the 
curves are broken because of missing data, the broken ends 
will not be labeled. When the humidity is missing for the 
FMH#3 
