geoid

geoidi, geoidipinta puhekieltä The shape that the surface of the oceans of the Earth would take under the influence of the Earth's gravity and rotation alone, extending also through the continents, disregarding other factorNoun factors such as winds and tides; that is, a surface of constant gravitational potential at zero elevation.
(quote-book)|seriesvolume=no. 48|location=Washington, D.C.|publisher=w:United States Government Publishing Office|Government Printing Office|year=1888|page=15|pageurl=https://books.google.com/books?id=dIAfAAAAYAAJ&pg=PA15|oclc=459138679|passage=The problem of the form and dimensions of the sea level surface of the earth has been one of peculiar difficulty. The combined efforts of the ablest mathematicians of the past two centuries, supplemented by the most laborious and costly geodetic measurements have yielded us the first approximation only to the complete solution. (..) This spheroid, or reference ellipsoid, as it is sometimes called, has its minor axis coincident with the earth's axis of rotation and is usually regarded as sensibly fixed in position and dimensions. With respect to it the actual sea surface or geoid must be imagined to lie partly above and partly below by small but unknown amounts, the determination of which, if possible, will constitute a second approximation to the figure of the earth.
(quote-book) Publication; no. 1357|location=Washington, D.C.|publisher=American Geophysical Union of the (w)—w:National Research Council (United States)|National Research Council|year=1966|page=87, column 2|pageurl=https://books.google.com/books?id=ckQrAAAAYAAJ&pg=PA87|oclc=976894946|passage=In an earlier paper at Berkeley last year Durbin, 1963, I suggested correlations between the local crust and the corresponding geoid undulation. Comparisons of crustal thickness with various geoids (gravimetric, astrogeodetic, and satellite) showed a general compatibility, not only in the United States but also in various other parts of the world.
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puhekieltä (l)