Compare Frenchprojection zénithale (1866 or earlier).
Meaning & use
1877–
Any of a class of map projections in which a portion of the globe is projected on to a plane tangential to a point on that portion, usually made the centre of the map; also called azimuthal projection.
Common forms are the zenithal (or azimuthal) equal-area projection, devised by the Swiss mathematician Johann Heinrich Lambert in 1772, and the zenithal (or azimuthal) equidistant projection.
1877
Lambert's Zenithal Projection resulted in a far less amount of distortion than those of Sanson or Bonne.
Geogr. Magazine March 81/2
1882
The name zenithal projections is..derived from the fact that they can always be considered as the representation of the hemisphere situated above the horizon of the given point, and having the zenith for pole.
T. Craig, Treat. on Projections v. 89
1974
Gnomic map, type of zenithal projection in which the Earth's grid is projected by radials from a point at the centre of the sphere into a tangent plane so that all great circles are represented by straight lines.
Encyclopædia Britannica Micropædiavol. IV. 587/3
2004
We derive the exact..transformations for the zenithal projections most commonly used in astronomy.
Publications of Astronomical Society of Pacificvol. 116 971/1
zenithal projection typically occurs fewer than 0.01 times per million words in modern written English.
zenithal projection is in frequency band 2, which contains words occurring between 0.001 and 0.01 times per million words in modern written English. More about OED's frequency bands
Frequency data is computed programmatically, and should be regarded as an estimate.
Frequency of zenithal projection, n., 1890–2010
* Occurrences per million words in written English
Historical frequency series are derived from Google Books Ngrams (version 2), a data set based on the Google Books corpus of several million books printed in English between 1500 and 2010.
The overall frequency for a given word is calculated by summing frequencies for the main form of the word, any plural or inflected forms, and any major spelling variations.
For sets of homographs (distinct entries that share the same word-form, e.g. mole, n.¹, mole, n.², mole, n.³, etc.), we have estimated the frequency of each homograph entry as a fraction of the total Ngrams frequency for the word-form. This may result in inaccuracies.
Smoothing has been applied to series for lower-frequency words, using a moving-average algorithm. This reduces short-term fluctuations, which may be produced by variability in the content of the Google Books corpus.
Decade
Frequency per million words
1890
0.0029
1900
0.0031
1910
0.0038
1920
0.0038
1930
0.0046
1940
0.0042
1950
0.004
1960
0.0037
1970
0.0033
1980
0.0023
1990
0.0021
2000
0.0013
2010
0.0012
Originally published as part of the entry for zenithal, adj.