![]() Twilight has 3 sub categories, Civil, Nautical, and Astronomical. The reverse is true for morning twilight. Evening twilight starts when the Sun dips below the horizon and lasts until the Sun reaches 18° below the horizon. It is produced when sunlight scatters in the upper atmosphere, thereby illuminating the lower atmosphere, and results in the Earth’s surface not being completely lit, or completely dark. Twilight can best be defined as the illumination of the lower atmosphere when the sun is below the horizon and no longer directly visible. Dawn begins with the first sight of lightness (Astronomical twilight) in the morning, and continues until the sun peaks above the horizon. ![]() In other words, at the darkest stage of twilight.ĭawn is derived from Old English, and means to become day. ![]() Sunrise, sunset, and twlight chart Dusk and Dawnĭusk occurs at the very end of astronomical twilight after sunset and just before night. As such, daylength gets longer during the summer months, and shorter during the winter months. Longitude, Latitude, and date must be taken into account to properly calculate sunrise, sunset, and twilight times.ĭaylength is total amount of daylight hours in a day, and is typically calculated as the hours between sunrise and sunset. Sunrise and sunset vary throughout the year, and depend on time of year, and location on the planet. Sunset is typically defined as the instant when the Sun is no longer visible in the western horizon. ![]() Sunrise over the beach © / hokle1305 Sunrise is typically defined as the exact instant which the Sun is visible in the Eastern horizon. ![]()
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