Owing to refraction (the bending of the light rays by the atmosphere) this actually occurs when the sun's centre appears to be about its own diameter above the horizon.
Ukutyala ukutshintsha kwindlela (ukugoba komgca wesikhanyisi ngomoya ojikeleza umhlaba) le nto yenzeka ingakumbi xa umbindi welanga uvela njengomgca ohamba ukusuka kwicala ukuya kwelinye udlula kumbindi wesangqa ngaphezulu komgca odibanisa isibhakabhaka nomhlaba.