7/v'./.V.V.///„/iV//l" A'.//>/() TF.l.lil'IIOXi: I K.IXS.UISSlOX 481 



rise in Kn^land. TIuto is a certain deviation, however, wliirh it is 

 well to {M>int out. Durinj; the sutnnier months the rise in niRht-time 

 static starts several hours iK'fore and reaches hi^;h values at about 

 hUnset in En^iand, whereas in the winter-time, the niKht-timcstatic 

 Ijcgins to rise at ai)out sunset and reaches high values several houf.v 

 Liter. .\ similar elTect is ol)ser\ed for the sunrise <-oiiditioii wherein 



FcaxuAOt 



UiKN 

 MT 



tUCUST 



NOV cue CR 

 DccnetPt 



■ooi usMioai nooi 



Fig. 18— Seasonal variation in dislrihution of {laytimc and night time noise with 

 respect to sunset and sunrise. New Southgate, England — 1923-1924 



the reduction of static sets in during the summer months about the 

 time of sunrise, reaches low daylight values several hours later, and 

 in the winter the reduction commences se\eral hours before sumise 

 and reaches low daylight values at sunrise. In other words, the rise 

 to high night-time values occurs earlier with respect to sunset in the 

 summer than in the winter, and conversely the fall from high night- 

 time static to the lower daylight values occurs later with respect to 

 sunrise, in the summer than in the winter. 



This is more definitely brought out in Fig. 18 which combines 

 the data for all frequencies measured. The dash-lines associated 

 with the sunset curves, delineate the beginning and the attainment 

 of the night-time increases and those associated with the sunrise 

 curve delineate the Ix-ginning and the attainment of the low daylight 

 values. This discloses the fact that sunset and sunrise at the receiving 



