Identifier: smithsonianmisce821931sm (find matches)
Title: Smithsonian miscellaneous collections
Year: 1862 (1860s)
Authors: Smithsonian Institution
Subjects: Science
Publisher: Washington : Smithsonian Institution
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Smithsonian Libraries

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land, Oregon, preceded those at Toronto by about0.75 year. The difi^erence in longitude is 43°. At that rate the epochwould move about 150° of longitude in one period, or approximatelyaround the world in two periods. The charts given by Dr. Weickmann in his study of the 24-dayperiod referred to previously do- not show the drift in longitude soclearly as the drift in latitude. However, in his charts there arefound centers of maximum departure which show a drift in longi-tude. A center in the Aleutian Islands on December 10, 1923, movedeastward across Canada to Labrador in 11 days, which is at the rateof about one period for 180° of longitude; but a center near Green-land moved eastward to northern Siberia and then retreated. The longitude drift of the waves is, hence, not so clearly definedas the latitude drift; but there is undoubtedly a trend which may bestated as follows: ^ Monthly Weather Review, Vol. 52, No. i, p. 39, Jan., 1924. 28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
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iG. 18.—Departures of pressure in 7.5-year period, epochs i(1889, 1891. NO. 7 Till-: ATMOSTHERE AND THE SUN CLAYTON 29 Laiv of longitude displacement of periodic zuavcs.—Periodic wavestend to drift eastward at a rate of 180° of longitude in one period,whatever the length of the periofl. The centers of greatest departureare found in high latitudes, 60° to 80° from the Equator. There are several factors which make this drift toward the eastdifificult to follow. First there are the factors depending on solarchanges descrihed in the latitude efifect and which are nearly instan-taneous with solar changes. There are also seasonal factors andprobably others which influence the results. Examining the successive charts in figure 18 it is found that themagnitude of the departures in the 7.5-year period decreased rap-idly as the central areas passed into Siberia and increased againover Kamchatka. This enhanced intensity in the departures coincidedwith a maximum of solar activity as will b

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