Blue hour
The blue hour (from
The blue hour occurs when the Sun is far enough below the horizon so that the sunlight's blue wavelengths dominate due to the
The blue hour is shorter in regions near the equator due to the sun rising and setting at steep angles. In places closer to the poles, the illumination and twilight periods are longer as the sun rises and sets at shallower angles.[4]
Explanation and times of occurrence
The still commonly presented incorrect explanation claims that Earth's post-sunset and pre-sunrise atmosphere solely receives and disperses the sun's shorter blue wavelengths and scatters the longer, reddish wavelengths to explain why the hue of this hour is so blue.[5] In fact, the blue hour occurs when the Sun is far enough below the horizon so that the sunlight's blue wavelengths dominate due to the Chappuis absorption caused by ozone.[2]
When the
Blue hour usually lasts about 20–96 minutes right after sunset and right before sunrise. Time of year, location, and air quality all have an influence on the exact time of blue hour.[7] For instance in Egypt (every 21st of June), when sunset is at 7:59 PM: blue hour occurs from 7:59 PM to 9:35 PM. When sunrise is at 5:54 AM: blue hour occurs from 4:17 AM to 5:54 AM. Golden hour occurs from 5:54 AM to 6:28 AM and from 7:25 PM to 7:59 PM.
Blue hour in art
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Die blaue Stunde (1890), painting by Max Klinger
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Sunset (1897), painting by António Cândido da Cunha
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Twilight (1897), painting by Edmund Tull (Ödön Tull)
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Taj-Mahal, twilight (1920), woodcut by Charles W. Bartlett
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Evening at the Lumber Yards of Kiba (1920), woodcut byKawase Hasui
Blue hour photography
Many artists value this period for the quality of the soft light. Although the blue hour does not have an official definition, the blue color spectrum is most prominent when the Sun is between 4° and 8° below the horizon.[6]
Photographers use blue hour for the tranquil mood it sets. When photographing during blue hour it can be favourable to capture subjects that have artificial light sources, such as buildings, monuments, cityscapes, or bridges.
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The City of London during the blue hour
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Praia da Ursa, Cabo da Roca, Portugal. A wide-angle view of the seascape during the blue hour
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Zug, Switzerland during the blue hour
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Padmanabhaswami Temple of Kerala during the blue hour
See also
Notes
- ^ A similar calque is used in many languages.[citation needed]
References
- ISBN 9780978708559.
- ^ ISBN 978-0-691-12453-7.
- ^ "The Blue Hour". timeanddate.com. Retrieved 6 April 2019.
- ISBN 978-1-59485-839-0.
- ^ "What is the blue hour? Learn about this magic time between daylight and darkness". mnn.com. Retrieved 7 April 2019.
- ^ a b "Blue Hour – Magic Hour". timeanddate.com. Retrieved 16 October 2017.
- ^ "What is the blue hour?". earthsky.org. 30 August 2014. Retrieved 7 April 2019.