| 释义 |
ˌsemi-diˈurnal, a.
[semi- 6 a.]
1. Astron. Pertaining to, consisting of, or performed in, half the time between the rising and setting of a celestial body. Chiefly in semi-diurnal arc.
1594Blundevil Exerc. iii. xviii. (1597) 154 It deuideth the artificial day and artificiall night each of them into two parts, that is to say, into two semi-diurnall and into two seminocturnall parts. Ibid. l. 176 b, There will remaine 9. houres 4′8. which is the length of the artificiall day, when the Sunne is in the first degree of Scorpio, the one halfe wherof is called the semi-diurnall Arke of that artificial day. 1664Wakely Mariners-Compass rectified (1694) 93 Astronomical Tables of Semidiurnal and Seminocturnal Arches. 1725Watts Geog. & Astron. xix, The difference between the sun or star's semidiurnal arc and a quadrant or ninety degrees. 1852Hind Astron. Vocab. 52 Semi-diurnal Arc, is half the arc described by a heavenly body between its rising and setting. 1867G. F. Chambers Astron. Vocab. 801.
2. Occurring every twelve hours. Chiefly of the tides.
1794R. J. Sulivan View Nat. I. 414 The tides are semi-diurnal polar effusions, as the general currents of the ocean are semi-annual. 1813J. Forbes Oriental Mem. I. 309 The sole cause then of these semidiurnal breezes, being the capacity which the earth has for acquiring a higher temperature than that of the sea. 1866Lockyer Guillemin's Heavens 59 The semi-diurnal oscillatory movement of the waters of the ocean,—the tides.
3. Ent. Partly diurnal, flying at twilight.
In recent Dicts. |