Abstract
LONDON Royal Society, November 7. F. W. G. WHITE and L. W. BROWN: Some measurements of the reflection coefficient of the ionosphere for wireless waves. The Breit and Tuve technique for ionospheric investigation is employed, the sender-receiver system being calibrated so that the reflection coefficient may be determined for a wave of any frequency within the range 2-80-6-50 Mc/s, from the relative amplitudes of the direct and the singly reflected atmospheric waves. Examples of measurements, made at noon during the period November 1934-May 1935, show that the total absorption suffered by the waves is very much dependent upon the critical phenomena at the transition of reflection from one region to another. The influence of the absorbing regions is estimated from the results. Estimates, based upon Appleton's theoretical formula, of the collisional frequency of the electrons with gas molecules in the F2 ionised region of the upper atmosphere, are made. The collisional frequency is of the order 5 × 103 per second at a height of approximately 250 km. above the surface of the earth. J. P. GOTT: The electric charge collected by water-drops falling through a cloud of electrically charged particles in a vertical electric field. Measurements were made of the charge collected by a large water drop falling through a jet of the cloud containing equal numbers of positively and negatively charged cloud particles in a vertical electric field maintained between two horizontal field plates. When the upper plate was positive, the drop collected a negative charge, and when the upper plate was negative the drop collected a positive charge. This is in agreement with a theory proposed by Wilson in connexion with the mechanism of thunderclouds. The quantitative agreement is as close as could be expected from the experimental arrangement. The experiments also afforded a test of the mechanism suggested by Elster and Geitel. If any charge was collected by the operation of this mechanism, it was too small to be observed.
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Societies and Academies. Nature 136, 806 (1935). https://doi.org/10.1038/136806b0
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DOI: https://doi.org/10.1038/136806b0