Sunrise effects inFregion from high speed ionospheric recordings

Abstract

High-speed recordings of the ionosphere from May 5 to June 10, 1949, reveal that time of initial “sunrise effect” followed ground sunrise in all instances. The average time-interval was approximately 15 minutes. At the first part of the observing period the observations were farthest removed from time of ground sunrise. Early in June, however, the observations approached time of ground sunrise. Scattered values appear to deviate in groups several minutes above or below a smooth curve. Such time fluctuations may be attributed to variations of absorption coefficient of the gas through which the ionizing radiation passes.