This effect is more pronounced closer to the poles, where the Sun rises at the vernal equinox and sets at the autumn equinox, with a long period of twilight, lasting for a few weeks. This can have a potential impact on the times and durations of dawn and dusk. Astronomical dawn ĭaytime becomes longer as the summer solstice approaches, while nighttime gets longer as the winter solstice approaches. These categories are astronomical, nautical, and civil dawn. This morning twilight before sunrise is divided into three categories depending on the amount of sunlight that is present in the sky, which is determined by the angular distance of the centre of the Sun ( degrees below the horizon) in the morning.
"Dawn" derives from the Old English verb dagian, "to become day".ĭawn begins with the first sight of lightness in the morning, and continues until the Sun breaks the horizon. This morning twilight period will last until sunrise (when the Sun's upper limb breaks the horizon), when direct sunlight outshines the diffused light.Ĭivil, nautical, and astronomical dawn, when defined as the beginning time of the corresponding twilight Etymology It is recognized by the appearance of indirect sunlight being scattered in Earth's atmosphere, when the centre of the Sun's disc has reached 18° below the observer's horizon. Late summer dawn over the Mojave Desert, California Dawn is sometimes considered the beginning of morning twilight, the period of twilight, or the time of sunrise.ĭawn is the time that marks the beginning of twilight before sunrise. For other uses, see Dawn (disambiguation).
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