Sunspots Affect Radio Wavelengths

Northern Advocate, 9 April 1943, Page 6

Sunspots Affect Radio Wavelengths

LONDON, April 8

An experiment with an important bearing on long-distance radio broadcasting was described by Sir Edward A. Appleton, when lecturing before the Institute of Electrical Engineers. He said the work began in 1931, when he, in co-operation with Mr R. Naismith, devised a radio method of measuring the concentration of electricity in the atmosphere 60 to 160 miles above ground. They suspected, after two years that this electron concentration was varying, in sympathy with the appearance of sunspots, and realised the need for observation of a complete sunsnot cycle of just over 11 years. Observations were now being made in other parts of the world, but British records were the longest available, and it was expected to show that some of the ultra-violet light emitted from the sun increased as much as 120 per cent as sunspot activity changed from minimum to maximum conditions. But the light thus changed was absorbed in the upper atmosphere and therefore was not detectable from the ground. International Agreement Needed Sir Edward Appleton concluded: It is now certain that the range of shortwave lengths available for long-dis-tance radio broadcasting increases very substantially with solar activity. Therefore it is certainly necessary that international allocation of such wavelengths after the war should take account of variations during the sunspot cycle indicated by these new re-