. The Bell System technical journal . pendicular to the plane of its orbit about the sun. As I heearth revolves about the sun, the sunlit hemisphere gradually extendsfarther and farther northward in the si>ring months and by the summersolstice reaches well l)eyond the north pole, as indicated in Fig. !).As the earth continues to revolve about the sun, the sunlit hemisj^hererecedes southward until at the winter .solstice it fails considerablyshort of the north pole and extends correspondingly beyond thesouth pole. Since the transatlantic path lies fairly high in the north-ern latitude, it is
. The Bell System technical journal . pendicular to the plane of its orbit about the sun. As I heearth revolves about the sun, the sunlit hemisphere gradually extendsfarther and farther northward in the si>ring months and by the summersolstice reaches well l)eyond the north pole, as indicated in Fig. !).As the earth continues to revolve about the sun, the sunlit hemisj^hererecedes southward until at the winter .solstice it fails considerablyshort of the north pole and extends correspondingly beyond thesouth pole. Since the transatlantic path lies fairly high in the north-ern latitude, it is not surprising that the transmission conditions dis- ih:i\\ric 4f lliis seasonal iii-thifiue ill shiflinjj the diurnal transmissiim rharailerislic is ln-ttershown in l\^. 10. This tij^ure consists of the same monthly averagediurnal ciirNes ,is an- .issemhled in Fig. 8, arranged one aliove thecitlur instead of side h\ Kig. 9—Signal lii-lil Jiiiic—.Night conditions showiiii; proximity of transmissionpath to sunlit heniisphcrc In particular, there should be noted: 1. The time at which the sunset dip occurs changes with the changein time of sunset. 2. Similarly, the time at which liie morning drop in field streiigtlioccurs changes with the time of sunrise. 3. The period of high night-time values, boinided between thetime of sunset in the Inited States anil the time of sunrise in ICiiglaiid,is much longer in the winter than in the summer months. It is also to be observed that, as a rule, full night-time values ofsignal field strength are not attained until some time after sunset atthe western terminal and that they begin to decrease before sunriseat the eastern terminal. In other words, the daylight effects appearto extend into the period in which the transmission path along theearths surface is unexposed to direct rays of the sun. The effectof this is that with the advance of the season from winte
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
