2.
Nuclear Burst Parameters for Yield Estimation.
Nuclear burst parameters have been correlated with yield and are presented
in nomograms, each of which is an independent means of determining an
estimated yield (Figures 1-3 and 1-4). An estimated yield can be determined
from nomograms, if any of the following combinations of burst parameters
(listed in order of decreasing reliability) are known.
Distance to ground zero (or flash-to-bang time) and nuclear burst
angular cloud width, measured 5 minutes after detonation.
Stabilized cloud-top or cloud-bottom height.
Distance to ground zero (or flash-to-bang time) and stabilized
cloud-top or cloud-bottom angle.
Illumination time (least reliable).
A primary measurement is the time from "flash-to-bang".
This is the time
interval, in seconds, between the detonation, "blue-white flash," and
arrival of the sound of the explosion or the shock wave at the observer's
position. The sound of the explosion travels at an average velocity of 350
meters (1122.8 ft.) per second. The distance, in meters, from an observer
to ground zero can be estimated by multiplying the flash-to-bang time in
seconds by 350.
Divide the product by 1000 to obtain the distance in
kilometers from the explosion to the observer. The distance may be obtained
directly from the nomogram using the scales on the right side, as shown in
Figure 1-4.
A second measurement is the azimuth from the observer to the mushroom stem
or cloud center. This reading should be made immediately after the passage
of the shock wave or bang from the explosion. This measurement is reported
to the TOC of higher headquarters to assist in locating ground zero. The
width of the nuclear cloud burst is measured by an observer 5 minutes after
the time of detonation.
This angular dimension is measured in mils or
degrees.
Two important cloud angle measurements are (1) stabilized cloud-top angle
and (2) stabilized cloud-bottom angle. Each of these measurements is made
approximately 10 minutes after the burst.
The stabilized cloud-top angle is the vertical angle in mils or degrees
measured from ground level to the top of the cloud.
Likewise, the
stabilized cloud-bottom angle is the vertical angle in mils or degrees
measured from ground level to the intersection of the stabilized cloud and
the stem (Figure 1-2).
CM5206
1-4
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