The Lunar Tide in the Atmosphere

Abstract

TIDAL theory was first applied with any success to the atmosphere by Laplace, and he also first attempted to determine the tidal variation of pressure from barometric observations. His material consisted of 4752 measurements of the height of the mercury column at Brest (lat. 49° N.). These were far too few for the purpose, however, and his result, given in tome v. of the “Mecanique Céleste,” cannot be regarded as a determination of the quantity sought for, which is much smaller than Laplace's value. Another lunar reduction of barometric data from Brest was made ! about thirty years ago by Bouquet de la Grye, but his series of observations (consisting of hourly values extending over a few years), while larger than that used by Laplace, still seems to have been inadequate. He arrived at a lunar daily inequality of pressure which was not by any means nearly semidiurnal in type, though the semidiurnal component—0.020 sin (2t+ 100°) mm. of mercury—was larger than the probable true value of the tidal variation at Brest.