National Geographic : 1946 Sep
S.. . .. ppears dark t A1 ere '5 ov Sr (>? Sounding Balloon 25 lDra n b lr\'in ] .*llei an *^do OZ*ONE LA.YE"R. .. Q. Diagram of Atmosphere to 300-mile Height Shows New World Aloft Now Being Explored . :;;:On way down they create reflecting layers of ionosphere (E, , F) which bend long-distance radio beams back" +:' "" S pt Airplane 13.7 Miles. . . . o. *. . . ' F1 0 - 6 . :..* f 1 e . . . * I . c*; -, * . I)ran by Irvin E. Alpcmaiii Diagram of Atmosphere to 300-mile Height Shows New World Aloft Now Being Explored Cosmic rays penetrate to earth's surface. Ultraviolet rays from sun mostly reach only to ozone layer (below). On way down they create reflecting layers of ionosphere (E, F1 , F 2) which bend long-distance radio beams back toward earth. Particles from sun produce aurora and disturb ionosphere. Aurora is seen from 50 to 600 miles aloft, but most often at altitudes shown here. Heights in miles are on a scale decreasing upward.