day = 24h = 84,600s

distance of sun from its axis of rotation = (around) 10,000km

daily journey of sun = 62,000km

speed of sun = 62,000 / 84,600 = 0.732km/s = 2,638km/h

if the sun were 10km above the ground, the distance in which the sun is above 45 degrees over the horizon = 20km

duration sun would be above aforementioned angle = 20km / 0.732km/s =    27.29s