refractive index profiles, ~.e , they are conducive to anomalous
prop?gatioll effects. The a priori probability of su'..:h a result, from
a truly random sample of dates-times~places is roughly on the order
of one chance in 200,000 (assuming that the probability of clear
weather is roughly 0.5 in any single case).
(2) Of the 19 cases, all but two occur during the night.
Although AP often occurs durin~ the daytime, the nighttime hours are
generally reare favorable, and tend to greatly increase the a p~iori
probability of encountering AP.
(3) In the 11 cases for which pertinent meteorological data are
available, in every case the refractive index profile is favorable,
to a greater or Ie ser dvgree, for the presence of anomalous propagatloll
effects. The weakest case, the data for SilveJ' Hill, 19 .Jul>' 1952,
(see p. 47). where inadequacies in the data were pointed out, has
- 1
a near-super~refractive surface luyer (gradient -81 ppm. km ) and an
elevated subrefractive layer. Of the remaInIng 11 profilps, seven
showing decting gradients (-157 ppm, km -lor greater negative value)
and four show super-refractive gradients ( 00 to -157 ppm. km- 1).
Since the a pl"l:ori probabi li ty of the OCCllueilCC of such proflles is
on the order of 0.25 (Bean, 196ob), the a pY'iol"i probability of this
resu'.t, give:, a truly r'i\ndom sample, is on the order of one in IOU
In overall summary of these rt~sul ts, us they pertain to an(.lnlalous
propu~atioli of radio or optical waves, it Beems that where the obser-
vational data pointed to anomalous propagation as the probable cause
of un UFO incident, the meteorological Jut!/. UTe overwhelmingly 1n
favor of the plausibility of the AP hypothp.sis. Tha, this result
coulJ have been only coinciJental has been shown to \H' 0;:' Iy remotely
probabll'.
,t. Conclusions Hnd ReCOllll11",ndatiolls for Further Work-_._----.... _--_.~._.-.. __.._------.....-------------
The following conclusions can be stat()u us a result of the investi-
gation reported in thi!; chapter:
refractive index profiles, ~.e • they are conducive to anomalous
prop2gatioll effects. The a pnori probability of sU'.;h a result, from
a trU!f random sample of dates-times-places is roughly on the order
of one chance in 200,000 (assuming that the probability of clear
weather is roughly O.S in any single case).
(2) Of the 19 cases, all but two occur during the night.
Although AP often occurs during the daytime, the nighttime hours Bre
general Iv more favorable, and tend to greatly increase the a priori
probability of encountering AP.
(3) In the 11 cases for which pertinent meteorological data are
available, ill every case the refractive index profile is favorable,
to a greater or Ie ser d~gree, for the presence of anomalous propagatioll
effects. The weakest case, the urlta for Silv<!J' Hill, 19 ,July 1952,
(see p. 47), where inadequacies in the data were pointed out, has
- 1
a near-super-refractive surface layer (gradient -81 ppm. km ) and an
elevated subrefractive layer. Of the remaining 11 profil~s, seven
-1
showing decting ~radients (-157 ppm, km or greater neRKtiv~ value)
-1
and four show super-refractive gradients ( 00 to -157 ppm. km ).
Since the a prl:ori probability of the occuuence of such profiles is
on the order of 0.25 (Bean, 196bb), the Cl }YrioY'i probability of this
rcsu'. t, gi ve:l a truly r<lndom sample, is on the order of one in 10v.
In overall ~ummary of these rl~sul ts, U5 they pertaln to anomalous
propu&ation of radio or optical waves, it acems that where the obser-
vational data pointed to anomalous propagation as the probable cause
of un UFO incident, the meteorological uuta ure overwhelmingly 1n
favor of the plausibility of the AP hypothesis. Tha. this result
coulu have been only cnincilientul has been shown to \)(' ,;,'Iy remotely
probable.
·1. CO}lc~':lsi_~ llnd ~~_t~~~.!2.~~!..l)lIS fo.!_J.:~_~theJ' W()r~
The following cunclusions can be stated us a result of the investi-
gation reported in this chapter: