Length of Day


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Length of Day

 

the interval of time between sunrise and sunset, during which the sun is above the horizon. The length of day depends upon the geographic latitude of a place and upon the inclination of the sun. At the equator, the length of day is constant and equals 12 hours. In the northern hemisphere, the length of day is more than 12 hours during the positive inclination of the sun (that is, in the spring and summer) and less than 12 hours during the negative inclination of the sun (in the autumn and winter). At the equinoxes (spring and autumn), the day equals the night (if one does not consider refraction) everywhere on the earth. The longest day is the summer solstice and the shortest is the winter solstice. Within the polar circles, the length of day in the summer can exceed 24 hours (the polar day), and at the poles daytime lasts six months.

References in classic literature ?
An astrolabe was an instrument used in astronomy to find out the distance of stars from the earth, the position of the sun and moon, the length of days, and many other things about the heavens and their bodies.
If you fly to the Canadian city of Calgary, the length of day changes by nearly nine whole hours.
This is because the length of day is not constant but depends on the epoch in which it is measured.
They also found the earthquake decreased the length of day by 2.
A study of the period 1964-1987 shows that the ENSO has twice the strength of the QBO in affecting the length of day.
Planet Length of year Length of day Your age Your age (in Earth days) (in Earth hours) in Earth in Earth Years Days Mercury 87.
Scientists have long known that the earth's rotation rate, which determines the length of day, can be sped up or slowed down by winds blowing on mountains.
The two mesh with lovely accuracy; the problem is that the length of day is infinitesimally slowing - and so once in a while, when the International Earth Rotation and Reference System Service decrees - most recently on Dec.
After incorporating newly available stratospheric wind data, the meteorologists conclude that "tropospheric plus stratospheric winds can fully account for seasonal, nontidal changes in the length of day [or rotation rate] without invoking other geophysical processes.
Pity the houseplants, as many of them are native to the equatorial areas of the world, where the length of day and of night remains nearly equal year-round.