Does sunrise mean the Sun is fully up?
Quick Answer: No, sunrise does not mean the Sun is fully up. It marks the moment the Sun’s upper edge first appears above the horizon, not when the entire Sun is visible.
Sunrise is the instant the very top edge of the Sun becomes visible. The Sun itself is a disk, so at sunrise, only a small part peeks over the horizon.
It takes a few more minutes for the whole Sun to clear the horizon. During that time, the Sun appears to "rise" gradually until fully visible.