PREPARATION OF CHARTS B5-15 
pressure data block corresponding to the next higher standard 
isobaric surface. This sumis the altitude of that standard iso- 
baric surface above mean sea ievel. 
7.1 Thickness of Layers Between Standard Isobaric Surfaces. The 
standard isobaric surfaces are listedin Table 7, and are printed as heavy 
horizontal lines on WBAN-31( ). The thickness of each layer will be 
computed either by means of height tabs printed on the charts, or by 
means of Table 7. Preference is given to the first of the two methods. 
A height tab scale is provided for most of the strata. Each division of 
the scale is equal to 10 geopotential meters, and the spacing between the 
tabs is sufficient for the scale to be read to the nearest whole meter with 
an accuracy of +2 meters. To find the thickness of the stratum, use the 
point on the height tab scale corresponding to the mean virtual tempera- 
ture. If the thickness tabs are omitted, or appear in error (see JA4-1.1), 
Wes 
S19 
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PSN CHEESE HEE 
SOSRS/USNANGSSRSUSORERGSHEENWERRRERS. Ai 
ctl ha a ama pit tt 950 = 
ee NE LL at geeccca oer = 
a | A a Seaaee= 
AOA ees’ cH pty PINE Tee 
ee ine aff 
SESESSSSSRSRREN SU LEESEEES 2 
oo EOeeeeeeee 
PELE EPpy TEE Hr iso 
nal a PEE 30 Tene 
Figure B5 - 6, Determination of Thickness of Stratum 
1-1-69 FMH#3 
