9/10/2023 0 Comments Twilight dawn duskExtra amounts of dust in the atmosphere from volcanic eruptions and dust storms can intensify the effect. Be sure to watch for the " purple light" about 20-30° above the western horizon about 30 minutes after sunset it's caused by sunlight reflected from aerosols in the lower stratosphere mingling with the still-blue sky. Lower clouds are rarely illuminated with the intensity of higher cloud formations because sunlight is greatly attenuated by dust and haze in the lowest part of the atmosphere during its downward journey. Reds, oranges, and yellows remain to liven the sky and turn the underbellies of higher clouds vivid scarlet and pink. Layers of twilight seen in late civil and the first half of nautical twilight. Because sunlight must travel a long, horizontal path through the thickest part of the atmosphere at and after sunset, the great density of air molecules and aerosols scatter away all the violets and blues. In the east, Earth's dusky shadow rises, topped by a pink sash known as the Belt of Venus. Our planet's shadow is visible any clear evening "rising" in the east just after sunset or setting in the west shortly before sunrise. Earth's shadow topped by the Belt of Venus and the full Moon. Assuming the evening sky is free of haze, scattered light from the just-set Sun colors the western horizon bright yellow, which deepens to orange and orange-red as the minutes pass. The crescent Moon and Venus first appear in the west (when visible). There’s still enough sunlight reflecting off the atmosphere to see your way around and recognize faces and landmarks. It's divided into three varieties that depend on how far the Sun is below the horizon.Ĭivil twilight begins at sunset and ends when the center of the Sun is 6° below the horizon. Twilight comes in three different flavors depending upon the Sun's altitude below the horizon: Twilight is the time when the Sun illuminates the lower atmosphere after sunset or before sunrise. That's since been shaved down to 1 hour and 51 minutes at my latitude and will reach a minimum of 1 hour and 42 minutes in early September. Back in June, twilight lingered nearly three hours, leaving a skimpy three hours of darkness before the start of dawn. Not only have sunset and sunrise times conspired to extend the night at the expense of day, but twilights are shorter, too. At dawn, the world comes back to life, starting from stillness and ending with sunrise and the sound of traffic.ĭarkness comes earlier now than it did in June and July. Evening twilight may bring a welcome relief from a hot summer day or anticipation of a clear night for skywatching. Many of us cherish the interval after sunset or before sunrise as an opportunity for contemplation. I wouldn't mind spending time on the Moon, but I'd miss dusk and dawn. Twilight takes us gently into that good night. Clouds glow an intense pink in early twilight. We explore twilight's brief but fascinating sights and learn why it gets shorter as summer turns to fall. Blue Hour - all names for that colorful and contemplative time between day and night.
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