560:, the relative increased reflection of solar radiation of snow and ice). Even at the summer solstice, when the Sun reaches its highest point above the horizon at noon, it is still only 23.44° above the horizon at the poles. Additionally, as one approaches the poles the apparent path of the Sun through the sky each day diverges increasingly from the vertical. As summer approaches, the Sun rises and sets become more northerly in the north and more southerly in the south. At the poles, the path of the Sun is indeed a circle, which is roughly equidistant above the horizon for the entire duration of the daytime period on any given day. The circle gradually sinks below the horizon as winter approaches, and gradually rises above it as summer approaches. At the poles, apparent sunrise and sunset may last for several days.
904:
267:
245:, when the continuing rotation of the Earth causes the Sun's disc to disappear below the horizon to the west. Because the Sun is a luminous disc as seen from the Earth, rather than a point source of light, sunrise and sunset are not instantaneous and the exact definition of both can vary with context. Additionally, the Earth's atmosphere further bends and diffuses light from the Sun and lengthens the period of sunrise and sunset. For a certain period after sunset and before sunrise, indirect light from the Sun lightens the sky on Earth; this period is often referred to as
129:
539:
horizon. There will also be days when the Sun never rises above the horizon. This number will be fewer, but close to the number of days in the summer where the sun doesn't set (for example the sunrise is usually a few days before the spring equinox and extends a few days past the fall equinox). This phenomenon of more daylight than night is not unique to the poles. In fact, at any given time slightly more than half of the earth is in daylight. The 24 hours of summer daylight is known as the
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764:
988:
141:
39:
952:
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Although the daytime length at the
Equator remains 12 hours in all seasons, the duration at all other latitudes varies with the seasons. During the winter, daytime lasts shorter than 12 hours; during the summer, it lasts longer than 12 hours. Northern winter and southern summer concur, while northern
233:
with the direction of sunlight), and so the length of the daytime period varies from one point on the planet to another. Additionally, since the axis of rotation is relatively fixed in comparison to the stars, it moves with respect to the Sun as the planet orbits the star. This creates seasonal
597:
are located, the seasonal difference is smaller, but still results in approximately 4 hours difference in daylight between the winter and summer solstices. The difference becomes less pronounced the closer one gets to the equator. An approximation to the monthly change can be obtained from the
538:
Around the poles, which coincide with the rotational axis of Earth as it passes through the surface, the seasonal variations in the length of daytime are extreme. In fact, within 23.44° latitude of the poles, there will be at least some days each year during which the sun never goes below the
551:
marks the boundary. These boundaries correspond to 66.56° north or south latitude, respectively. Because the sky is still bright and stars can't be seen when the sun is less than 6 degrees under the horizon, 24-hour nights with stars visible all the time only happen beyond 73° north or south
214:. The area subjected to direct illumination is almost exactly half the planet; but because of atmospheric and other effects that extend the reach of indirect illumination, the area of the planet covered by either direct or indirect illumination amounts to slightly more than half the surface.
517:
On the
Tropical Circles, the Sun is directly overhead only once per year, on the corresponding solstice. At latitudes closer to the Equator and on the Equator itself, it will be overhead twice per year (on the equinoxes in the case of the Equator), leading to the
292:
A plot of hours of daylight as a function of the date for changing latitudes. This plot was created using the simple sunrise equation, approximating the sun as a single point and does not take into account effects caused by the atmosphere or the diameter of the
386:
to be cold. The slight effect of daylight hours on average seasonal temperature can be seen with the poles and tropical regions. The poles are still cold during their respective summers, despite seeing 24 hours of daylight for six months, while the
283:
481:
because the Sun's path across the sky is so nearly perpendicular to the horizon. On the equinoxes, the solar disk takes only two minutes to traverse the horizon (from top to bottom at sunrise and from bottom to top at sunset).
584:
are located, the difference in the length of the day from summer to winter can be very noticeable: the sky may still be lit at 10 pm in summer, but may be dark at 5 pm in winter. In the lower middle latitudes where southern
555:
At and near the poles, the Sun never rises very high above the horizon, even in summer, which is one of reasons why these regions of the world are consistently cold in all seasons (others include the effect of
370:. While increased daylight can have some effect on the higher temperatures in the summer, most of temperature rise results from the directness of the Sun, not the increased daylight. The high
252:
Certain groups, such as
Earthly astronomers, do not consider daytime to be truly ended until the Sun's disc is actually well below the Earth's horizon, because of this indirect illumination.
506:, because when it was named, the Sun passed overhead at this location at the time of year when it was near the constellation of Cancer. The equivalent line of south latitude is called the
221:
of Earth experiencing daytime at any given instant changes continuously as the planet rotates on its own axis. The axis of the Earth's rotation is not perpendicular to the plane of its
287:
286:
288:
510:, for similar reasons. The sun enters and leaves each zodiacal constellation slightly later each year at the rate of about 1 day every 72 years. For more information, see
285:
183:
facing the Sun. In direct sunlight the movement of the sun can be recorded and observed using a sundial that casts a shadow that slowly moves during the day. Other
407:, the daytime period always lasts about 12 hours, regardless of season. As viewed from the Equator, the Sun always rises and sets roughly vertically, following an
49:
712:
202:
Very broadly, most humans tend to be awake during some of the daytime period at their location, and asleep during some of the night period.
284:
572:, far from both the Equator and the poles, variations in the length of daytime are moderate. In the higher middle latitudes where
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and the day of the year. Latitude 40° N (approximately New York City, Madrid and
Beijing) is highlighted as an example.
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107:
79:
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851:
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is the time elapsed between beginning and end of the daytime period. Given that Earth's own axis of rotation is
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20:
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of the celestial sphere from the
September equinox to the March equinox. On the equinoxes, the equatorial Sun
1008:
698:
27:
383:
271:
128:
241:, when the Earth's rotation towards the east first causes the Sun's disc to appear above the horizon, to
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The period of daytime from the standpoint of a surface observer is roughly defined as the period between
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The fact that the equatorial Sun is always so close to the zenith at solar noon explains why the
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contains the warmest regions on the planet overall. Additionally, the
Equator sees the shortest
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The tropics occupy a zone of Earth's surface between 23.44° north and 23.44° south of the
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of due east and sets within 23.44° south of due west. The Sun's path lies entirely in the
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variations in the length of the daytime period at most points on the planet's surface.
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199:, also experience daytime, but this article primarily discusses daytime on Earth.
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502:) on at least one day per year. The line of 23.44° north latitude is called the
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622:; the magnitude of variation is about 30 minutes over the course of a year.
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from the March equinox to the
September equinox, but lies entirely in the
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of due east, and sets within 23.44° north of due west. From the
September
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remains warm throughout the year, with only 12 hours of daylight per day.
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phenomenon. Outside the tropics, the Sun never passes directly overhead.
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350:. Their tilt toward the Sun leads to more than half of the day seeing
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The same Rule of
Twelfths can be applied to the duration of the days.
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16:
Period of a day in which a location experiences natural illumination
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to be warm, while low angles (barely above the horizon) causes the
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in the sky, varies with the seasons. This variation is called the
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Approximately half of Earth is illuminated at any time by the
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that is famous in some northern countries. To the north, the
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of solar rays, the longer period of daytime itself, and less
56:
26:"Length of day" redirects here. Not to be confused with
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on the planet's surface, depending on the observer's
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Daytime length variations with latitude and seasons
346:. Areas tilted toward the Sun are experiencing
547:marks this 23.44° boundary. To the south, the
706:
494:. Within this zone, the Sun will pass almost
8:
65:introducing citations to additional sources
438:to the March equinox, the Sun rises within
354:and warmer temperatures, due to the higher
713:
699:
691:
163:during which a given location experiences
338:, the length of daytime varies with the
330:23.44° to the line perpendicular to its
55:Relevant discussion may be found on the
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658:
7:
666:McAdam, Marcus (14 November 2019).
395:summer and southern winter concur.
191:that rotate relative to a luminous
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48:relies largely or entirely on a
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144:A daytime sky with white clouds
1:
134:Brisbane Water National Park
614:, when the Sun reaches its
512:precession of the equinoxes
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259:
171:. Daytime occurs when the
25:
18:
760:
606:Variations in solar noon
378:) of the Sun causes the
175:appears above the local
21:Daytime (disambiguation)
430:, the Sun rises within
28:Day length fluctuations
668:"The Rule of Twelfths"
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312:Earth daylight on the
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301:Earth daylight on the
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145:
137:
610:The exact instant of
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159:is the period of the
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632:Daylight saving time
165:natural illumination
61:improve this article
19:For other uses, see
564:At middle latitudes
508:Tropic of Capricorn
672:Mc2Photography.com
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295:
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195:, such as a local
189:natural satellites
146:
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1014:Time in astronomy
890:
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647:Sunshine duration
496:directly overhead
428:September equinox
314:December solstice
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642:Sunrise equation
620:equation of time
600:rule of twelfths
570:middle latitudes
549:Antarctic Circle
534:Around the poles
504:Tropic of Cancer
448:celestial sphere
324:daytime duration
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270:Day length as a
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206:Characteristics
155:as observed on
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486:In the tropics
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399:At the Equator
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320:Daytime length
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59:. Please help
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847:Belt of Venus
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830:Brahmamuhurta
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824:Witching hour
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637:Solar eclipse
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616:highest point
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545:Arctic Circle
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471:tropical zone
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452:southern half
449:
445:
444:northern half
441:
437:
433:
429:
425:
424:March equinox
420:
418:
414:
413:perpendicular
410:
409:apparent path
406:
398:
396:
392:
390:
385:
384:polar regions
381:
377:
373:
369:
365:
361:
357:
353:
349:
345:
341:
337:
334:, called the
333:
332:orbital plane
329:
325:
321:
315:
310:
304:
303:June solstice
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78: –
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72:Find sources:
66:
62:
58:
52:
51:
50:single source
46:This article
44:
40:
35:
34:
29:
22:
981:Solar System
872:Midnight sun
828:
730:
681:
675:. Retrieved
671:
661:
609:
595:South Africa
567:
554:
541:midnight sun
537:
525:
521:Lahaina Noon
519:
516:
489:
468:
440:23.44° south
432:23.44° north
421:
402:
393:
374:(around the
323:
319:
318:
246:
236:
216:
209:
201:
193:primary body
167:from direct
152:
148:
147:
114:
104:
97:
90:
83:
71:
47:
969:Outer space
957:Spaceflight
877:Polar night
852:Golden hour
721:Parts of a
225:around the
136:, Australia
132:Sunrise in
1003:Categories
857:Terminator
677:2021-03-11
653:References
612:solar noon
587:California
552:latitude.
464:solar noon
456:culminates
368:atmosphere
360:absorption
356:directness
260:See also:
229:(which is
219:hemisphere
181:hemisphere
117:March 2021
87:newspapers
933:Astronomy
867:Moonlight
801:Blue hour
749:Afternoon
500:culminate
422:From the
411:close to
76:"Daytime"
57:talk page
862:Daylight
819:Midnight
773:Twilight
626:See also
574:Montreal
364:sunlight
352:daylight
344:latitude
336:ecliptic
276:latitude
272:function
262:Sun path
248:twilight
231:parallel
169:sunlight
993:Science
921:Weather
895:Portals
840:Related
786:Sunrise
754:Evening
739:Morning
731:Daytime
582:Ushuaia
492:Equator
475:sunrise
458:at the
446:of the
436:equinox
426:to the
417:horizon
415:to the
405:Equator
403:At the
389:Equator
380:tropics
366:in the
340:seasons
239:sunrise
185:planets
177:horizon
149:Daytime
101:scholar
791:Sunset
558:albedo
479:sunset
460:zenith
376:zenith
372:angles
348:summer
328:tilted
243:sunset
103:
96:
89:
82:
74:
945:Stars
811:Night
591:Egypt
578:Paris
223:orbit
157:Earth
108:JSTOR
94:books
796:Dusk
781:Dawn
744:Noon
593:and
580:and
498:(or
293:sun.
217:The
197:star
187:and
80:news
723:day
568:At
524:or
477:or
362:of
322:or
274:of
227:Sun
212:Sun
173:Sun
161:day
153:day
151:or
63:by
1005::
680:.
670:.
602:.
589:,
576:,
514:.
466:.
419:.
897::
714:e
707:t
700:v
250:.
119:)
115:(
105:·
98:·
91:·
84:·
67:.
53:.
30:.
23:.
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