What is the blue hour?

Photo: Tom Tom/Shutterstock

If you harbor a passion for photography, you may already be well-acquainted with the magical light that appears during the so-called golden hour. However, there's another time of day that also has the power to make photographers and other artists sigh — the blue hour.

While most people might just refer to it as "twilight," this time of day is characterized by its ... well, blueness. Specifically, a vibrant deep shade of blue that we've all witnessed at one time or another.

The blue hour typically occurs for about 40 minutes twice a day — once right before the sun pops up in the morning and once right after the sun dips below the horizon following the evening sunset. The reason the hue is so overwhelmingly blue is because the Earth's pre-sunrise and post-sunset atmosphere only receives and scatters the sun's shorter blue wavelengths. Meanwhile, the sun's longer red wavelengths pass on into space without reaching the planet's surface.

Blue Hour: Ho Chi Minh, VIetnam

Photo: xuanhuongho/Shutterstock

Because the quality of light is everything when it comes to photography, the blue hour is often called "sweet light" by photographers.

This time of day is an especially great opportunity to shoot long-exposure night shots of cities, like the one above of Ho Chi Minh City in Vietnam. Because there's still a little bit of the sun's ambient light left to help illuminate detail in the subjects, photographers can achieve a vivid yet balanced picture that highlights the iconic luminosity of artificial lights without casting everything else into shadow.

Although cityscapes come out phenomenally well in blue hour photos, the possibilities are truly endless. In the photo below, we see a quiet, sublime scene of a shipwreck caught along the shore in Chonburi, Thailand.

Blue Hour: Chonburi, Thailand

Photo: pixbox77/Shutterstock

Want to find out when the blue hours occur in your area at this moment? The website BlueHourSite.com can tell you the exact start and end times for the morning and evening blue hours in any given area and date.

Continue below for more examples of what photographers are capable of when shooting during this beautiful time of day.

Blue Hour: New Taipei City, Taiwan

Photo: NH/Shutterstock

New Taipei City, Taiwan

Blue Hour: Eiffel Tower, Paris, France

Photo: pigprox/Shutterstock

Eiffel Tower, Paris, France

Blue Hour: Bangka, Sumatra

Photo: Anirut Krisanakul/Shutterstock

Bangka Island, Sumatra

Blue Hour: Brooklyn Bridge, NYC

Photo: dibrova/Shutterstock

Brooklyn Bridge, New York City

Blue Hour: Negev Desert, Israel

Photo: Michal Szymanski/Shutterstock

Negev Desert, Israel

Blue Hour: the Louvre, Paris, France

Photo: David Ionut/Shutterstock

The Louvre, Paris, France

Blue Hour: Hatinh, Vietnam

Photo: Michael Hero/Shutterstock

Hatinh, Vietnam

Blue Hour: Suratthani, Thailand

Photo: Settawat Udom/Shutterstock

Suratthani, Thailand

Blue Hour: Turin, Italy

Photo: pcruciatti/Shutterstock

Turin, Italy

* * *
Catie Leary is a photo editor at Mother Nature Network. Follow her on Twitter and Google+.
Want to see more great photos? Check out MNN's photo blog

Catie Leary ( @catieleary ) writes about science, travel, animals and the arts.

What is the blue hour? Learn about this magic time between daylight and darkness
You may already be familiar with the golden hour, but did you know there's another time of day that has the power to make photographers sigh?