diurnal adj
1. belonging to or active during the day; "diurnal animals are active during the day"; "diurnal flowers are open during the day and closed at night" [ant: nocturnal]
2. having a daily cycle or occurring every day; "diurnal rhythms"; "diurnal rotation of the heavens"; "the diurnal slumber of bats"

Parallax \Par"al*lax\, n. [Gr. ? alternation, the mutual inclination of two lines forming an angle, fr. ? to change a little, go aside, deviate; ? beside, beyond + ? to change: cf. F. parallaxe. Cf. Parallel.]
1. The apparent displacement, or difference of position, of an object, as seen from two different stations, or points of view.
2. (Astron.) The apparent difference in position of a body (as the sun, or a star) as seen from some point on the earth's surface, and as seen from some other conventional point, as the earth's center or the sun. Annual parallax, the greatest value of the heliocentric parallax, or the greatest annual apparent change of place of a body as seen from the earth and sun; as, the annual parallax of a fixed star. Binocular parallax, the apparent difference in position of an object as seen separately by one eye, and then by the other, the head remaining unmoved. Diurnal, or Geocentric, parallax, the parallax of a body with reference to the earth's center. This is the kind of parallax that is generally understood when the term is used without qualification. Heliocentric parallax, the parallax of a body with reference to the sun, or the angle subtended at the body by lines drawn from it to the earth and sun; as, the heliocentric parallax of a planet. Horizontal parallax, the geocentric parallx of a heavenly body when in the horizon, or the angle subtended at the body by the earth's radius. Optical parallax, the apparent displacement in position undergone by an object when viewed by either eye singly. --Brande & C. Parallax of the cross wires (of an optical instrument), their apparent displacement when the eye changes its position, caused by their not being exactly in the focus of the object glass. Stellar parallax, the annual parallax of a fixed star.

Diurnal \Di*ur"nal\, a. [L. diurnalis, fr. dies day. See

See more meaning on Diurnal...

• Diurnal: Diurnal ("daily ") may refer to: Diurnality , the behavior of animals and plants that are active in the daytime. Diurnal motion , the ...
• Diurnality: Animals that are not diurnal might be nocturnal (active at night) or crepuscular (active primarily during twilight , i.e., ...
• Diurnal motion: Diurnal motion is an astronomical term referring to the apparent daily motion of star s around the Earth , or more precisely around the ...
• Diurnal temperature variation: Diurnal temperature variation is a meteorological term that relates to the variation in temperature that occurs from the highs of the day ...
• Diurnal cycle: A diurnal cycle is any pattern that recurs every 24 hours as a result of one full rotation of the Earth In climatology , the diurnal cycle ...
• Diurnal phase shift: In telecommunication , diurnal phase shift is the phase shift of electromagnetic signals associated with daily changes in the ionosphere . ...

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