On Dec 21, 2016 (Summer Solstice in the Southern Hemisphere) ...
(1) Punta Arenas, Chile (southernmost city south in South America) had 17 hrs of daylight, 7 hrs of twilight, and 0 hrs of night
https://www.timeanddate.com/sun/chile/punta-arenas (2) Invercargill, New Zealand (southernmost city below Australia, but not quite as far south as (1) above) had 16 hrs of daylight, 5-1/2 of twilight, and only 2-1/2 hrs of night.
https://www.timeanddate.com/sun/new-zealand/invercargill (3) Cape Town, South Africa (southernmost city on the African continent, but not quite as far south as (2) above) had 14-1/2 hrs of daylight, 3-1/2 hrs of twilight, and only 6 hrs of night.
https://www.timeanddate.com/sun/south-africa/cape-town Explain exactly how three of the southernmost cities in the Southern Hemisphere all experienced in excess of 14-hr days and less than 6-hr nights when each location occupies a different "third" of the flat-earth map? How was there no night-time for Punta Arenas the same day the sun was shining brightly in both Invercargill AND Cape Town? Wouldn't the sun have to have left that "third" of the map COMPLETELY in order for the other two cities each to have experienced over 14 hrs of direct sunlight that day?
Stated another way, what could possibly explain the fact that the sun rose and could be seen at its normal location for the southernmost tip of South America, hang in the sky for 17 hours, then set in its normal location (without really setting this time since it is twilight instead of night for the next seven hours), THEN race around the rest of the outside border of the flat-earth map in record time, and rise again at the normal location for the southernmost tip of South America seven hours later?
Did the rest of the southern world get only seven hours of sun on Dec 21, 2016? Nope, because we also know that the southernmost tip of New Zealand saw the sun in its sky for 16 hours that same day, and the southernmost tip of South Africa saw the sun in its sky for over 14 hours that same day.
Let's assume there is at least SOME overlap between the time New Zealand's sun set and South Africa's sun rose, before it set again in South Africa and rose again in South America. Could ALL of that sun activity have happened in just seven hours? Is it even possible on a flat-earth map?