se
cist
ceetate
axis; and if the wind shear is greater than 120° then
crattin Mitcerriiatl
the fall-out area from the mushroom is circular,
This
ellipse would be centered at a point 7500 ft below the
tep af the mushroom, and it will be referra. to as
Ellipse A.
Within Ellipse A draw 4 second elliptical
area and call this Ellipse B.
The major axis of Hllipse
Bis 1/2 the major axis of Ellipse A, and the ratios of
majer to minor axis for the two ellipses are the same.
Fall-out Prom Stem
Draw an elliptical area from ground sero to a point
representing 25,000 ft msl level on the wind vector
plot.
The minor aris is 1/4 the major axis.
This rec-
tangular or elliptical area is called Ellipse ©,
within
Ellipse C draw Ellipse D starting from ground zero to
en Diener ee
a point representing the 20,000 ™ msl level on the
Wind vector plot with minor axis 1/4 major axis.
Similarly draw Ellipse E from ground zero to 15,000
ft mal level.
Fall-out Connecting Stem and Mishroom Areas.
The fall-out outside of the stem and mushroom areas
cannot be drawn by any specified methods,
However, the
———o
general fall-out from ground zero sut to 150 niles
appears to cover a pie-shaped area with an apex angle
of 15 to 30°.
It 1s recommended that this procedure
pi
be following in the construction of the fcrecast fall-out
¢ 23 B4g7 f ia
AAR
(7+)
CUSSED
3eeitiiip