571:, 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.
915:
278:
256:, 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
140:
550:
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
320:
309:
927:
775:
999:
152:
50:
963:
987:
939:
975:
951:
405:
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
244:
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
608:
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
549:
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
562:
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
225:. 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.
528:
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
303:
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
397:
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
294:
492:
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).
595:
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
566:
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
381:. 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
263:
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.
517:, 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
232:
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
298:
297:
299:
521:, 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
296:
194:
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
418:, 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
60:
723:
213:
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.
295:
583:, far from both the Equator and the poles, variations in the length of daytime are moderate. In the higher middle latitudes where
277:
382:
75:
462:
454:
905:
716:
144:
289:
and the day of the year. Latitude 40° N (approximately New York City, Madrid and
Beijing) is highlighted as an example.
522:
118:
90:
1024:
862:
337:
is the time elapsed between beginning and end of the daytime period. Given that Earth's own axis of rotation is
97:
31:
465:
of the celestial sphere from the
September equinox to the March equinox. On the equinoxes, the equatorial Sun
1019:
709:
38:
394:
282:
139:
252:, when the Earth's rotation towards the east first causes the Sun's disc to appear above the horizon, to
248:
The period of daytime from the standpoint of a surface observer is roughly defined as the period between
104:
919:
319:
308:
642:
370:
191:
774:
86:
991:
926:
518:
450:
378:
241:
203:
979:
967:
867:
480:
The fact that the equatorial Sun is always so close to the zenith at solar noon explains why the
484:
contains the warmest regions on the planet overall. Additionally, the
Equator sees the shortest
657:
438:
324:
199:
943:
652:
630:
610:
580:
559:
514:
458:
442:
366:
537:
501:
The tropics occupy a zone of Earth's surface between 23.44° north and 23.44° south of the
453:
of due east and sets within 23.44° south of due west. The Sun's path lies entirely in the
1003:
931:
892:
678:
245:
variations in the length of the daytime period at most points on the planet's surface.
151:
1013:
857:
840:
834:
647:
555:
434:
423:
342:
313:
111:
998:
955:
882:
605:
551:
531:
210:, also experience daytime, but this article primarily discusses daytime on Earth.
887:
626:
513:) on at least one day per year. The line of 23.44° north latitude is called the
510:
466:
49:
622:
597:
474:
338:
17:
877:
811:
759:
633:; the magnitude of variation is about 30 minutes over the course of a year.
461:
from the March equinox to the
September equinox, but lies entirely in the
445:
of due east, and sets within 23.44° north of due west. From the
September
402:
remains warm throughout the year, with only 12 hours of daylight per day.
872:
829:
783:
584:
541:
phenomenon. Outside the tropics, the Sun never passes directly overhead.
419:
374:
362:
354:
346:
286:
272:
258:
179:
175:
796:
764:
749:
592:
502:
485:
481:
446:
427:
415:
399:
390:
249:
187:
361:. Their tilt toward the Sun leads to more than half of the day seeing
801:
693:
The same Rule of
Twelfths can be applied to the duration of the days.
568:
506:
489:
470:
386:
358:
350:
253:
229:
195:
27:
Period of a day in which a location experiences natural illumination
950:
393:
to be warm, while low angles (barely above the horizon) causes the
821:
629:
in the sky, varies with the seasons. This variation is called the
601:
588:
318:
307:
292:
276:
233:
167:
150:
138:
701:
806:
791:
754:
207:
705:
733:
237:
222:
221:
Approximately half of Earth is illuminated at any time by the
183:
171:
43:
554:
that is famous in some northern countries. To the north, the
369:
of solar rays, the longer period of daytime itself, and less
67:
37:"Length of day" redirects here. Not to be confused with
71:
903:
353:
on the planet's surface, depending on the observer's
850:
820:
782:
740:
267:
Daytime length variations with latitude and seasons
357:. Areas tilted toward the Sun are experiencing
558:marks this 23.44° boundary. To the south, the
717:
505:. Within this zone, the Sun will pass almost
8:
76:introducing citations to additional sources
449:to the March equinox, the Sun rises within
365:and warmer temperatures, due to the higher
724:
710:
702:
174:during which a given location experiences
349:, the length of daytime varies with the
341:23.44° to the line perpendicular to its
66:Relevant discussion may be found on the
910:
669:
7:
677:McAdam, Marcus (14 November 2019).
406:summer and southern winter concur.
202:that rotate relative to a luminous
190:, that is, anywhere on the globe's
25:
997:
985:
973:
961:
949:
937:
925:
913:
773:
59:relies largely or entirely on a
48:
473:, passing directly overhead at
155:A daytime sky with white clouds
1:
145:Brisbane Water National Park
625:, when the Sun reaches its
523:precession of the equinoxes
1041:
270:
182:. Daytime occurs when the
36:
29:
771:
617:Variations in solar noon
389:) of the Sun causes the
186:appears above the local
32:Daytime (disambiguation)
441:, the Sun rises within
39:Day length fluctuations
679:"The Rule of Twelfths"
327:
323:Earth daylight on the
316:
312:Earth daylight on the
305:
290:
156:
148:
621:The exact instant of
322:
311:
302:
280:
170:is the period of the
154:
142:
643:Daylight saving time
176:natural illumination
72:improve this article
30:For other uses, see
575:At middle latitudes
519:Tropic of Capricorn
683:Mc2Photography.com
328:
317:
306:
291:
206:, such as a local
200:natural satellites
157:
149:
1025:Time in astronomy
901:
900:
658:Sunshine duration
507:directly overhead
439:September equinox
325:December solstice
300:
137:
136:
122:
16:(Redirected from
1032:
1002:
1001:
990:
989:
988:
978:
977:
976:
966:
965:
964:
954:
953:
942:
941:
940:
930:
929:
918:
917:
916:
909:
777:
726:
719:
712:
703:
696:
695:
690:
689:
674:
653:Sunrise equation
631:equation of time
611:rule of twelfths
581:middle latitudes
560:Antarctic Circle
545:Around the poles
515:Tropic of Cancer
459:celestial sphere
335:daytime duration
301:
281:Day length as a
132:
129:
123:
121:
80:
52:
44:
21:
1040:
1039:
1035:
1034:
1033:
1031:
1030:
1029:
1010:
1009:
1008:
996:
986:
984:
974:
972:
962:
960:
948:
938:
936:
924:
914:
912:
904:
902:
897:
846:
816:
778:
769:
736:
730:
700:
699:
687:
685:
676:
675:
671:
666:
639:
619:
577:
547:
538:zero shadow day
499:
412:
293:
275:
269:
219:
217:Characteristics
166:as observed on
133:
127:
124:
81:
79:
65:
53:
42:
35:
28:
23:
22:
15:
12:
11:
5:
1038:
1036:
1028:
1027:
1022:
1020:Parts of a day
1012:
1011:
1007:
1006:
994:
982:
970:
958:
946:
934:
922:
920:Earth sciences
899:
898:
896:
895:
893:Zodiacal light
890:
885:
880:
875:
870:
865:
860:
854:
852:
848:
847:
845:
844:
837:
832:
826:
824:
818:
817:
815:
814:
809:
804:
799:
794:
788:
786:
780:
779:
772:
770:
768:
767:
762:
757:
752:
746:
744:
738:
737:
731:
729:
728:
721:
714:
706:
698:
697:
668:
667:
665:
662:
661:
660:
655:
650:
645:
638:
635:
618:
615:
576:
573:
546:
543:
498:
497:In the tropics
495:
411:
410:At the Equator
408:
331:Daytime length
268:
265:
218:
215:
135:
134:
70:. Please help
56:
54:
47:
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
1037:
1026:
1023:
1021:
1018:
1017:
1015:
1005:
1000:
995:
993:
983:
981:
971:
969:
959:
957:
952:
947:
945:
935:
933:
928:
923:
921:
911:
907:
894:
891:
889:
886:
884:
881:
879:
876:
874:
871:
869:
866:
864:
861:
859:
858:Belt of Venus
856:
855:
853:
849:
843:
842:
841:Brahmamuhurta
838:
836:
835:Witching hour
833:
831:
828:
827:
825:
823:
819:
813:
810:
808:
805:
803:
800:
798:
795:
793:
790:
789:
787:
785:
781:
776:
766:
763:
761:
758:
756:
753:
751:
748:
747:
745:
743:
739:
735:
727:
722:
720:
715:
713:
708:
707:
704:
694:
684:
680:
673:
670:
663:
659:
656:
654:
651:
649:
648:Solar eclipse
646:
644:
641:
640:
636:
634:
632:
628:
627:highest point
624:
616:
614:
612:
607:
603:
599:
594:
590:
586:
582:
574:
572:
570:
564:
561:
557:
556:Arctic Circle
553:
544:
542:
540:
539:
534:
533:
526:
524:
520:
516:
512:
508:
504:
496:
494:
491:
487:
483:
482:tropical zone
478:
476:
472:
468:
464:
463:southern half
460:
456:
455:northern half
452:
448:
444:
440:
436:
435:March equinox
431:
429:
425:
424:perpendicular
421:
420:apparent path
417:
409:
407:
403:
401:
396:
395:polar regions
392:
388:
384:
380:
376:
372:
368:
364:
360:
356:
352:
348:
345:, called the
344:
343:orbital plane
340:
336:
332:
326:
321:
315:
314:June solstice
310:
288:
284:
279:
274:
266:
264:
262:
260:
255:
251:
246:
243:
239:
235:
231:
226:
224:
216:
214:
211:
209:
205:
201:
197:
193:
189:
185:
181:
177:
173:
169:
165:
161:
153:
146:
141:
131:
120:
117:
113:
110:
106:
103:
99:
96:
92:
89: –
88:
84:
83:Find sources:
77:
73:
69:
63:
62:
61:single source
57:This article
55:
51:
46:
45:
40:
33:
19:
18:Length of day
992:Solar System
883:Midnight sun
839:
741:
692:
686:. Retrieved
682:
672:
620:
606:South Africa
578:
565:
552:midnight sun
548:
536:
532:Lahaina Noon
530:
527:
500:
479:
451:23.44° south
443:23.44° north
432:
413:
404:
385:(around the
334:
330:
329:
257:
247:
227:
220:
212:
204:primary body
178:from direct
163:
159:
158:
125:
115:
108:
101:
94:
82:
58:
980:Outer space
968:Spaceflight
888:Polar night
863:Golden hour
732:Parts of a
236:around the
147:, Australia
143:Sunrise in
1014:Categories
868:Terminator
688:2021-03-11
664:References
623:solar noon
598:California
563:latitude.
475:solar noon
467:culminates
379:atmosphere
371:absorption
367:directness
271:See also:
240:(which is
230:hemisphere
192:hemisphere
128:March 2021
98:newspapers
944:Astronomy
878:Moonlight
812:Blue hour
760:Afternoon
511:culminate
433:From the
422:close to
87:"Daytime"
68:talk page
873:Daylight
830:Midnight
784:Twilight
637:See also
585:Montreal
375:sunlight
363:daylight
355:latitude
347:ecliptic
287:latitude
283:function
273:Sun path
259:twilight
242:parallel
180:sunlight
1004:Science
932:Weather
906:Portals
851:Related
797:Sunrise
765:Evening
750:Morning
742:Daytime
593:Ushuaia
503:Equator
486:sunrise
469:at the
457:of the
447:equinox
437:to the
428:horizon
426:to the
416:Equator
414:At the
400:Equator
391:tropics
377:in the
351:seasons
250:sunrise
196:planets
188:horizon
160:Daytime
112:scholar
802:Sunset
569:albedo
490:sunset
471:zenith
387:zenith
383:angles
359:summer
339:tilted
254:sunset
114:
107:
100:
93:
85:
956:Stars
822:Night
602:Egypt
589:Paris
234:orbit
168:Earth
119:JSTOR
105:books
807:Dusk
792:Dawn
755:Noon
604:and
591:and
509:(or
304:sun.
228:The
208:star
198:and
91:news
734:day
579:At
535:or
488:or
373:of
333:or
285:of
238:Sun
223:Sun
184:Sun
172:day
164:day
162:or
74:by
1016::
691:.
681:.
613:.
600:,
587:,
525:.
477:.
430:.
908::
725:e
718:t
711:v
261:.
130:)
126:(
116:·
109:·
102:·
95:·
78:.
64:.
41:.
34:.
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
