![]() ![]() In Islam, Zodiacal Light (or "false dawn") is referred to as False Morning ( Subhe-Kazeb, Persian صبح کاذب) and Astronomical dawn is called Sahar ( سحر) or True Morning ( Subhe-Sadeq, Persian صبح صادق), and it is the time of first prayer of the day, and the beginning of the daily fast during Ramadan. When the Sun gets 9.0 to 9.5 degrees below the horizon (at summer solstice this is at latitudes 57☃0 ′–57☀0 ′), the zenith gets dark even on cloud-free nights (if there is no full moon), and the brightest stars are clearly visible in a large majority of the sky. Oslo, Norway at 59★6 ′ N, and Stockholm, Sweden at 59☁9 ′ N, seem very bright when the Sun is below the horizon. Example Īround the summer solstice, Glasgow, Scotland at 55★1 ′ N, and Copenhagen, Denmark at 55☄0 ′ N, get a few hours of "night feeling". This period of "bright nights" is longer at higher latitudes. Īt latitudes higher than about 60☃4 ′, summer nights get no darker than civil twilight. Near the summer solstice, latitudes higher than 54☃4 ′ get no darker than nautical twilight the "darkness of the night" varies greatly at these latitudes. This period of time with no sunset lengthens closer to the pole. Therefore, the angular radius of the polar circle is equal to the angle between Earth's equatorial plane and the ecliptic plane. The polar circle (at 66☃4 ′ north or south) is defined as the lowest latitude at which the Sun does not set at the summer solstice. 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. These are astronomical, nautical and civil twilight.ĭaytime becomes longer as the summer solstice approaches, while nighttime gets longer as the winter solstice approaches. The morning twilight is divided in three phases, which are 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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