c. Stabilized Cloud-Top Angle or Cloud-Bottom Angle.
The yield estimation (flash-to-bang time versus stabilized cloud-top
angle or stabilized cloud-bottom angle) nomogram (Figure 2-3) is used to
determine yield from distance-to-ground zero (or flash-to-bang time) and
either stabilized cloud-top or cloud-bottom angle measurements.
The
right hand scale gives the flash-to-bang time in seconds on the left side
and distance in kilometers to ground zero on the right side. The center
scale is the cloud-top angle or cloud bottom angle, measured in mils on
the left of the scale and in degrees on the right of the scale. The left
hand scale is actually two scales. On the left of the left hand scale
are listed the yields to be read when using the stabilized cloud bottom
angle measurements and on the right is the yield when using cloud-top
angle measurements.
To use Figure 2-3, place a hairline through the point on the right hand
scale representing distance-to-ground zero, or flash-to-bang time, and
through a point in the center scale representing either the cloud-top
angle measurement or the cloud-bottom angle measurement. At the point of
intersection of the hairline and the left hand scale, read the yield. If
a cloud-top angle measurement is used on the center scale, read the yield
on the right side of the left hand scale entitled "Yield (Cloud Top)." If
a cloud-bottom angle measurement is used, read the yield on the left side
of the left hand scale entitled "Yield (Cloud Bottom)."
For example, an observer reports a flash-to-bang time of 120 seconds,
angle to cloud top of 300 mils. Place a hairline from 120 seconds on the
flash-to-bang time scale through 300 mils on the left side of the angle
scale; the yield is read as 50 KT on the right side (cloud top) of the
yield scale. The observer may have reported a cloud-bottom angle of 200
mils. In this case, place the hairline from 120 seconds on the flash-to-
bang time scale through 200 mils on the left side of the angle of the
yield scale; the yield is read as 60 KT. It is emphasized that these
yield calculations are field estimates.
CM2307
2-6
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