photos taken at dawn (above) and then sunrise (below)
on September 24, 2011 with Lone Peak in the distance
Dawn is the time that marks the beginning of the twilight before sunrise. It is recognized by the presence of weak sunlight, while the sun itself is still below the horizon. Dawn should not be confused with sunrise, which is the moment when the leading edge of the sun itself appears above the horizon.
The duration of the twilight period between dawn and sunrise varies greatly depending on the observer's latitude. Dawn may easily be determined by observing a piece of thread. When the color of a thread can be determined, changing from black to the thread's distinctive color, the 'crack of dawn' has occurred.