noun
: the portion of the diurnal circle of a celestial body that is above the observer's horizon
the diurnal arc of the sun is its apparent path from sunrise to sunset
noun
: the portion of the diurnal circle of a celestial body that is above the observer's horizon
the diurnal arc of the sun is its apparent path from sunrise to sunset
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012