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December 20, 2017
A sunrise over the Bay of Bengal, Puducherry, India.
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December 7, 2017
A storm system spotted during the blue hour over Puducherry, India.
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2 thoughts on “A storm system spotted during the blue hour over Puducherry, India.”
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Ian, Photo Editor, CAS
Thanks very much for this explanation. This is new to me so I thank you for the useful enlightenment. As ever, there is so much to learn from the CAS.
You certainly know “cloud stuff!!
Best wishes.
Laurence
Definition of the Blue Hour
On a clear day, the transition between day and night can be a colorful spectacle, with the indirect sunlight tinting the sky yellow, orange, red, and blue. The blue hour refers to the phase of twilight when the Sun is so far below the horizon that the light’s blue wavelengths dominate.
Because the blue hour is a colloquial term, it doesn’t have an official definition similar to dawn, dusk, and the 3 phases of twilight. Rather, it refers to a state of natural lighting that usually occurs at daybreak in the morning and during the last stages of twilight in the evening.
However, the blue color spectrum is most likely to emerge when the Sun is between 4 and 8 degrees below the horizon. By this definition, the blue hour encompasses parts of both nautical twilight and civil twilight.