Latitude is just the tilt of the sun's circle

The sun traces a circle once a day, every day, everywhere on Earth. Only one thing changes from place to place: the angle that circle makes with your horizon — ninety degrees minus how far you stand from the equator. Vertical at the equator, so the sun rises straight up and night falls like a switch. Flat at either pole, so it spends half the year above the horizon and half below. Everywhere else is in between.