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daylight

 
Dictionary: day·light   (dā'līt') pronunciation
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n.
  1. The light of day; sunlight.
    1. Daybreak.
    2. Daytime.
  3. Exposure to public notice: corrupt business practices that were finally brought into the daylight.
  4. Understanding or insight into what was formerly obscure: new evidence that gave the researchers some daylight into the matter.
  5. Sports. An opening, as between defensive players, especially one providing an opportunity for action: The running back found some daylight and gained six yards.
  6. daylights Slang. One's wits: "His adventurism had scared the daylights out of them" (Frederick Forsyth).
idiom:

see daylight

  1. To make sufficient progress so that completion of a project seems possible.


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Antonyms:

daylight

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n

Definition: light part of hours
Antonyms: darkness, evening, night, sunset

Word Tutor:

daylight

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pronunciation

IN BRIEF: n. - The time after sunrise and before sunset while it is light outside.

pronunciation Cheerfulness keeps up a kind of daylight in the mind. — Joseph Addison

Aviation Dictionary:

daylight

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The period of time during any day that begins with the morning civil twilight and ends with the evening civil twilight. Civil twilight is the period before sunrise and after sunset when the sun’s center is between 0° and 6° below the horizon.
Wikipedia:

Daylight

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For other uses, see Daylight (disambiguation).
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 It has been suggested that this article or section be merged with Daytime (astronomy). (Discuss)
World map showing the areas of the Earth receiving daylight around 13:00 UTC, April 2nd.

Daylight or the light of day is the combination of all direct and indirect sunlight outdoors during the daytime (and perhaps twilight). This includes direct sunlight, diffuse sky radiation, and (often) both of these reflected from the Earth and terrestrial objects. Sunlight scattered or reflected from objects in outer space (that is, beyond the Earth's atmosphere) is generally not considered daylight. Thus, moonlight is never considered daylight, despite being "indirect sunlight". Daytime is the period of time each day when daylight occurs.

Contents

Definition

Daylight is present at a particular location, to some degree, whenever the sun is above the horizon at that location. (This is true for slightly more than 50% of the Earth at any given time. For an explanation of why it is not exactly half, see the section labeled "introduction" on the "day" article). However, the outdoor illuminance can vary from 120,000 lux for direct sunlight at noon, which may cause eye pain, to less than 5 lux for thick storm clouds with the sun at the horizon (even <1 lux for the most extreme case), which may make shadows from distant street lights visible. It may be darker under unusual circumstances such as a solar eclipse or very high levels of atmospheric smoke (See New England's Dark Day), dust,[1] or volcanic ash.[2]

Daylight intensity in different conditions

Artificial image showing a nightfall over Europe and Africa. The solar terminator is shown for UTC July 5, 2005 18.45.00
Illuminance Example
120,000 lux Brightest sunlight
110,000 lux Bright sunlight
20,000 lux Shade illuminated by entire clear blue sky, midday
10,000 - 25,000 lux Typical overcast day, midday
<200 lux Extreme of darkest storm clouds, midday
400 lux Sunrise or sunset on a clear day (ambient illumination).
40 lux Fully overcast, sunset/sunrise
<1 lux Extreme of darkest storm clouds, sunset/rise

For comparison, nighttime illuminance levels are:

Illuminance Example
<1 lux Moonlight[3]
0.25 lux Full Moon on a clear night[4][5]
0.01 lux Quarter Moon
0.002 lux Starlight clear moonless night sky including airglow[4]
0.0002 lux Starlight clear moonless night sky excluding airglow[4]
0.00014 lux Venus at brightest[4]
0.0001 lux Starlight overcast moonless night sky[4]

For a table of approximate daylight intensity in the Solar System, see sunlight.

Effects

Question book-new.svg
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Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (October 2008)
Daylight in January. Some people choose not to live in polar regions because of the extreme differences in the amount of daylight in summer and winter.

Daylight is widely accepted to have a positive psychological effect on the human being[citation needed], and consequently more cases of mental health problems are registered during the winter months than during the summer months due to the shortened periods of daylight[citation needed]. Cases of depression specifically linked to limited daylight are referred to as seasonal affective disorder.

Daylighting is lighting an indoor space with openings such as windows and skylights that allow daylight into the building. This type of lighting is chosen to save energy, to avoid hypothesized adverse health effects of over-illumination by artificial light, and also for aesthetics. Artificial lighting energy use can be reduced by simply installing fewer electric lights because daylight is present, or by dimming/switching electric lights automatically in response to the presence of daylight, a process known as daylight harvesting.

In recent years, work has taken place to recreate the effects of daylight artificially. This is however expensive in terms of both equipment and energy consumption and is applied almost exclusively in specialist areas such as filmmaking, where light of such intensity is required anyway.

See also

Notes

  1. ^ http://www.perryton.com/black.htm
  2. ^ http://volcanoes.usgs.gov/ash/
  3. ^ Bunning, Erwin; and Moser, Ilse (April 1969). "Interference of moonlight with the photoperiodic measurement of time by plants, and their adaptive reaction" ([dead link] – Scholar search). Proceedings of the National Academy of Sciences of the United States of America 62 (4): 1018–1022. doi:10.1073/pnas.62.4.1018. PMID 16591742. http://www.pnas.org/cgi/reprint/623/4/1018. Retrieved 2006-11-10. 
  4. ^ a b c d e Paul Schlyter, Radiometry and photometry in astronomy FAQ (2006)
  5. ^ "Petzl reference system for lighting performance". Archived from the original on 2008-06-20. http://web.archive.org/web/20080620123040/http://en.petzl.com/petzl/frontoffice/Lampes/static/referentiel/present_referentiel_en.jsp. Retrieved 2007-04-24. 

External links


This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Translations:

daylight

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Daylight

Dansk (Danish)
n. - dagslys, åbenhed, åbent vand

idioms:

  • daylight robbery    optrækkeri
  • daylight saving time    sommertid
  • daylight time    de lyse timer

Nederlands (Dutch)
daglicht, dageraad

Français (French)
n. - jour, lumière du jour, phares de jour, au grand jour

idioms:

  • daylight robbery    (GB) (être) du vol caractérisé, (être) de l'arnaque
  • daylight saving time    (GB) heure d'été
  • daylight time    pendant la journée

Deutsch (German)
n. - Tageslicht

idioms:

  • daylight robbery    (ugs.) Wucher
  • daylight saving time    Sommerzeit
  • daylight time    Sommerzeit

Ελληνική (Greek)
n. - φως της μέρας, χάραμα, χαραυγή

idioms:

  • daylight robbery    (καθομ.) αισχροκέρδεια (κν. χαράτσωμα, καθαρή ληστεία)
  • daylight saving time    θερινή ώρα
  • daylight time    (ΗΠΑ) θερινή ώρα

Italiano (Italian)
sensi, luce del giorno

idioms:

  • daylight robbery    furto alla luce del giorno
  • daylight saving time    ora legale
  • daylight time    ora legale
  • in broad daylight    in pieno giorno
  • knock the daylights out of    dar botte da orbi a

Português (Portuguese)
n. - luz (f) do dia

idioms:

  • daylight robbery    assalto (f) à luz do dia
  • daylight saving time    horário (m) de verão
  • daylight time    período (m) diurno
  • in broad daylight    em plena luz do dia
  • knock the daylights out of    apavorar

Русский (Russian)
свет, дневное время

idioms:

  • daylight robbery    ограбление средь бела дня
  • daylight saving time    летнее/зимнее время
  • daylight time    летнее время
  • in broad daylight    средь бела дня
  • knock the daylights out of    вышибить дух из кого-либо

Español (Spanish)
n. - luz del día, amanecer, conciencia pública, período del luz solar, espacio entre dos partes que debían estar juntas

idioms:

  • daylight robbery    robo, robo a mano armada, extorsión
  • daylight saving time    horario de verano, generalmente retrasando el reloj una hora
  • daylight time    hora de verano

Svenska (Swedish)
n. - dagsljus, gryning

中文（简体）(Chinese (Simplified))
白昼, 破晓, 日光

idioms:

  • daylight robbery    明目张胆的劫夺
  • daylight saving time    夏令时间, 日光节约时间
  • daylight time    白天

中文（繁體）(Chinese (Traditional))
n. - 白晝, 破曉, 日光

idioms:

  • daylight robbery    明目張膽的劫奪
  • daylight saving time    夏令時間, 日光節約時間
  • daylight time    白天

한국어 (Korean)
n. - 낮, 햇빛, (분명히 드러나는) 틈, 시력

日本語 (Japanese)
n. - 日光, 昼間, 夜明け, 知れわたること, 知識
v. - 日光をあてる

idioms:

  • daylight robbery    公然の泥棒行為, 法外な代金
  • daylight saving time    夏時間
  • daylight time    日光節約時間, 夏時間

العربيه (Arabic)
‏(الاسم) ضو النهار, وضح النهار‏

עברית (Hebrew)
n. - ‮אור היום, פתיחות, פומביות, שחר, בינה, שכל, רווח נראה לעין בין סירות מתחרות‬

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Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.  Read more
Idioms. The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Company. All rights reserved.  Read more
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Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "Daylight".  Read more
Translations. Copyright © 2007, WizCom Technologies Ltd. All rights reserved.  Read more

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