23857122-0457-180273-0367

a Je channel and so leads to a diminution of space charze from the environment of the path but an immediate in-~ crease Of ionization along its path. Following the passage of the phenomenon, ionization will decay by recombination. Nearby Air or Other Craft All metallic aircraft which are struck by true light- ning generully have scorch marks, pits, or holes burned through the skin. The holes rarely exceed one inch in diameter. (See N.A.C.A. Technical Note 1001). Portions of nonemetellic material im contact with the area struck may be burnt or explosively separated from the metal to which the materiai is attached. When radio antennae are struck or the lightning arrester does not function as f 4 e ’ i 4 1s : " Aaaed pa: rien me a - Ra ATA anwénman atran -¢ — aesLy IUy Uamea 3 GO Lala WMP ke a ined OL ten OhOl on Bs S ® Ay Temporary blinding of pilots looking directly at the flash due to the stroke to some exterior portion of the aircraft such as the nose of the fuselage may introduce some hazard. As a rule the temporary blinding is ef- fective from about 10 seconds to a larger fraction of a minute, but in one extreme case a copilot was reported to have been temporarily blinded for about & minutes. Several oases of temporary blinding of about 3 minutes have been reported. oe 4 The Weather Bureau has not received any reports of acci- dents in which an airplane Mia said to have suffered contact with "ball lightning. Judging by the phenomenon called by that name and experienced at the surface, the aircraft damage to be expected by such contact would probably be less severe than that caused by a typical genuine lightning stroke. That type of so-called "ball lightning" which is actually an intense corona discharve a & 13) ~ 8, would not cause any mechanical damage to non-inflammable exposed materials, but would hamper radio communications by producing static similar to the kind termed "precipi- tation static." A real lightning stroke to a non-metallic object on the ground often causes an explosive disruptive effect on the object and will cause burning of inflammable materials. Contact of so-called “bail lightning” may have physical effects on exposed persons varying from negligible to Declassification Authority: NND 57565