THE PRESENT STATUS OF RADIO ATMOSPHERIC 
DISTURBANCES? 
By L. W. AUSTIN 
Laboratory for Special Radio Transmission Research? 
Our knowledge concerning atmospheric disturbances is still very 
meager. The observed facts may be catalogued as follows: (1) 
In general, atmospherics are stronger at the longer wave lengths. 
(2) Except for the effects of local storms, they are nearly always 
stronger in the afternoon and night, while for the higher frequencies 
this increase in strength is confined usually to the night alone. (38) 
They are stronger in summer than in winter, (4) in the south than 
in the north, and (5) on the land than on the ocean. (6) A large 
proportion of them appear to be directive; that is, to come from 
definite regions, or centers, as mountain ranges, rain areas, or thun- 
derstorms. It is also reasonably certain that (7) at least most of 
the long-wave disturbances travel along the earth with a practically 
vertical wave front,’ like the signals; (8) that a considerable portion 
are oscillatory in character, though a certain portion are nonoscilla- 
tory and give rise to shock oscillations in the antenna at all wave 
lengths; and (9) that disturbances sometimes occur simultaneously 
at stations thousands of miles apart.* 
The crigin of the ordinary rumbling disturbances (grinders) has 
been the subject of many conjectures. Eccles ® believed at one time 
that he had found the source of this type of disturbance, as far as 
England was concerned, in distant thunderstorms, especially in 
Western Africa. “DeGroot ® has suggested that the grinders are due 
to the bombardment of the upper atmosphere by electrons from the 
sun or charged cosmic dust. The idea that this type of disturbance 
1Presented at the annual meeting of the Section of Terrestrial Magnetism and Elec- 
tricity of the American Geophysical Union, Washington, D..C., Apr. 30, 1925. Published 
by permission of the Director of the Bureau of Standards of the U. S. Department of Com- 
merce. Reprinted by permission from Journal of the Washington Academy of Sciences, 
vol. 16; No. 2, Jan. 19, 1926. 
2 Conducted jointly by the Bureau of Standards and the American Section of the Inter- 
national Union of Scientific Radio Telegraphy. 
3 Jour. Wash. Acad. Sci., 11: 101. 1921. 
£M. Baumler, Jahrb. d. Drabtlosen Teleg., 19: 325. 1922. This matter of simultaneous 
crashes needs further investigation since a certain number of such coincidences may eyi- 
dently occur by chance. 
5 Electrician (London), 69: 75. 1912. 
SPrOC., 1. uBies Won Oise h e- bo b< 
203 
