HEB: Haute Ecole de Bruxelles (French: High School of Brussels; Brussels, Belgium) HEB: Hindu Endowments Board (Singapore) HEB: Here Everything's Better: HEB: High Energy Biscuit: HEB: High-Energy Beam: HEB: High Efficiency Boiler: HEB: Health Evidence Bulletins: HEB: Heating Element Bank: HEB: Higher Education Bulletin (Kenya) HEB
Twilight is the time between darkness and sunrise in the morning, and sunset and complete darkness in the evening, when there is light outside, but the Sun is below the horizon. There are 3 types of twilight: civil, nautical, and astronomical. Dubai skyline in twilight.
Beginning of morning nautical twilight / End of evening nautical twilight. The beginning of morning nautical twilight and the end of evening nautical twilight occur when the zenith distance of the centre of the Sun's disk is 102Â°. For latitudes north of approximately 54.5Â° north, nautical twilight will not occur around the summer solstice.