noun
definition
A flower that opens only in the day.
definition
A book containing canonical offices performed during the day, hence not matins.
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A diary or journal.
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A daily news publication.
adjective
definition
Happening or occurring during daylight, or primarily active during that time.
example
Most birds are diurnal.
definition
Said of a flower open, or releasing its perfume during daylight hours, but not at night.
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Having a daily cycle that is completed every 24 hours, usually referring to tasks, processes, tides, or sunrise to sunset; circadian.
definition
Done once every day; daily, quotidian.
definition
Published daily.
Examples of diurnal in a Sentence
Take a base attached to the centre of the earth, but without this diurnal rotation.
The species of the genus Lemur are diurnal, and may be recognized by the length of the muzzle, and the large tufted ears.
This type of colouring is also found in genera of quite distinct sub-families of butterflies, namely in Danainae and Pierinae, as well as in some diurnal moths, all of which occur in the same district as the Ithomiinae.
The climate, influenced by the high elevation, is characterized by long and severe winters and short summers with great diurnal extremes of temperature.
The most important unofficial contemporary works are the Histories of John Knox, Bishop John Lesley, George Buchanan, and Robert Lindsay of Pitscottie; the Diurnal of Remarkable Occurrents from the death of James IV.
For instance, the velocity of propagation of a wave having a period of a day is nearly twenty times as great as that of a wave with a period of one year; but on the other hand the penetration of the diurnal wave is nearly twenty times less, and the shorter waves die out more rapidly.
Annual and Diurnal Variations.-At Wolfenbi ttel, Elster and Geitel found A vary but little with the season.
The diurnal mountain winds are very strongly marked on the Himalaya, where they probably are the most active agents in determining the precipitation of rain along the chain - the monsoon currents, as before stated, not penetrating among the mountains.
A more considerable defect is due to the earth having a diurnal rotation relative to a Newtonian base, and this is never wholly ignored.
Practically clocks are regulated by reference to the diurnal rotation of the earth relatively to the stars, which affords a measurement on the repetition principle agreeing with other methods, but more accurate than that given by any existing clock.
Diurnal Variation.-The apparent daily period at most stations is largely determined by the influence of daylight on the visibility.
It is only during winter and in high latitudes that we can hope to ascertain anything directly as to the real diurnal variation of the causes whose influence is visible at night as aurora.
Whilst daylight is the principal cause of the diurnal inequality, it is not the only cause, otherwise there would be as many auroras in the morning (forenoon) as in the evening (afternoon).
The preceding remarks relate to auroras as a whole; the different forms differ considerably in their diurnal variation.
The water-rat is perhaps the most often seen of all English mammals, owing to its diurnal habits.
This construction assumes that the sun describes daily a small circle about the pole of the celestial sphere, and ignores any diurnal variation in the declination.
For his demonstration in 1851 of the diurnal motion of the earth by the rotation of the plane of oscillation of a freely suspended, long and heavy pendulum exhibited by him at the Pantheon in Paris, and again in the following year by means of his invention the gyroscope, he received the Copley medal of the Royal Society in 1855, and in the same year he was made physical assistant in the imperial observatory at Paris.
On the north, the Himalaya range and the plateau of Afghanistan shut it off from the climate of central Asia, and give it a continental climate, the characteristics of which are the prevalence of land winds, great dryness of the air, large diurnal range of temperature, and little or no precipitation.
On the south the ocean gives it an oceanic climate, the chief features of which are great uniformity of temperature, small diurnal range of temperature, great dampness of the air, and more or less frequent rain.
Where accurate differential observations or photographs involving other than instantaneous exposures have to be made, the additional condition is required that the optical axis of the telescope shall accurately and automatically follow the object under observation in spite of the apparent diurnal motion of the heavens, or in some cases even of the apparent motion of the object relative to neighbouring fixed stars.
The results were, however, always untrustworthy owing to annual and diurnal changes in the instrument.
There are brisk diurnal sea-breezes, and seasonal trades and counter-trades.
Diurnal currents of wind, which are established from the plains to the mountains during the day, and from the hills to the plains during the night, are impqrtant agents in distributing the rainfall.
As he travels South, his zenith moves along the celestial sphere, and the circles of diurnal rotation become oblique to the horizon.
Finally, at the south pole the circles of diurnal revolution are again apparently horizontal, but are described in a direction apparently (but not really) the reverse of that near the north pole.
The other two systems, including the vernal equinox, are fixed on the celestial sphere, and so seem to us to perform a diurnal revolution from east towards west.
In astronomical practice is introduced a day, termed " sidereal," determined, not by the diurnal revolution of the sun, but of the stars.
The unceasing diurnal motion of the image of any heavenly body relative to the cross threads of a telescope makes a direct accurate measure of any co-ordinate except the declination almost impossible.
By revolving on this axis it follows a star in its diurnal motion, so that the star is kept in the field of view notwithstanding that motion.
His last telescopic discovery - that of the moon's diurnal and monthly librations - was made in 1637, only a few months before his eyes were for ever closed in hopeless blindness.
The transformation from apparent to topocentric consists of allowing for diurnal aberration.
They are predominantly diurnal (daytime) and feed on a variety of heathland plants.
Nocturnal intake rates were higher than diurnal intake rates owing to the consumption of more large earthworms at night.
Chart 2 is a diurnal nativity with the Sun in Aries.
Her slow steady plod is provided by the diurnal movement of the night sky.
The last group in the diurnal raptors is the true falcons.
In contrast diurnal species have a tau of greater than 24 hours.
In general there is far more diurnal and altitude related temperature variation than seasonal.
It presents a remarkable resemblance to the adjacent curve, which gives the diurnal variation at mid-winter at the Bureau Central.
The alteration that takes place in the regular diurnal inequality throughout the year is best seen by analysing it into a Fourier series of the type c 1 sin (t+ a l) +c2 sin (2t+ a 2)+c 3 sin (3t+a3)+c4 sin (4t+a 4)+..
Diurnal Variation.-At Karasjok Simpson found the mean values of I + and I_ throughout the whole year much the same between noon and I P.M.
At KremsmunsterZolss (41) finds a considerable similarity between the diurnal variations in q and in the potential gradient, the hours of the forenoon and afternoon maxima being nearly the same in the two cases.
Also the times of beginning and ending are difficult to define exactly, so that several elements of uncertainty exist in data as to the seasonal or diurnal variation.
For, on account of the diurnal motion, the direction of the axis of the telescope when pointed to a star is always changing, so that, to follow a star with an altazimuth mounting, the observer requires to move continuously the two handles which give slow motion in altitude and azimuth.
Now direct the telescope to a star near the equator and so that the star's image in its diurnal motion shall pass across the intersection of the two webs which mark the axis of rotation of the micrometer box.
Then, as the diurnal motion causes the star-image to travel away from the axis of rotation, the micrometer box is rotated till the image of the star when at a considerable distance from the axis is bisected by the position-web.
The micrometer is now clamped in position-angle by the clamp C, the star again brought back to the axis, and delicate adjustment given in position-angle by the slow-motion screw M, till the star-image remains bisected whilst it traverses the whole length of the position-web by the diurnal motion only.
Euphratean exploration has so far brought to light no traces of ecliptical partition by the moon's diurnal motion, unless, indeed, zodiacal associations be claimed for a set of twenty-eight deprecatory formulae against evil spirits inscribed on a Ninevite tablet.4 The safest general conclusions regarding this disputed subject appear to be that the sieu, distinctively and unvaryingly Chinese, cannot properly be described as divisions of a lunar zodiac, that the nakshatras, though of purely Indian origin, became modified by the successive adoption of Greek and Chinese rectifications and supposed improvements; while the manazil constituted a frankly eclectic system, in which elements from all quarters were combined.
The regular variations in pressure of the air indicated by the barometer and the annual and diurnal oscillations are as well marked in the Himalaya as elsewhere, but the amount of vapour held in suspension diminishes so rapidly with the altitude that not more than one-sixth (sometimes only one-tenth) of that observed at the foot of the mountains is found at the greatest heights.
These efforts have been very effective in removing the influence of the diurnal cycle from pulsation period measurements.