Time that marks the beginning of the twilight before sunrise
Dawn is the time that marks the beginning of twilight before sunrise. 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. This morning twilight period will last until sunrise (when the Sun's upper limb breaks the horizon), when direct sunlight outshines the diffused light. Etymology. "Dawn" derives from the Old English verb dagian, "to become day". Types of dawn. Dawn begins with the first sight of lightness in the morning, and continues until the Sun breaks the horizon.
https://en.wikipedia.org/wiki/Dawn
Dawn is the time that marks the beginning of twilight before sunrise. 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. This morning twilight period will last until sunrise (when the Sun's upper limb breaks the horizon), when direct sunlight outshines the diffused light. Etymology. "Dawn" derives from the Old English verb dagian, "to become day". Types of dawn. Dawn begins with the first sight of lightness in the morning, and continues until the Sun breaks the horizon.
