Beyond the tropics, the sunlight shines at an angle and is less intense. The Arctic and Antarctic circles are boundaries beyond which there is no sunlight for part of the year. These boundaries are so important that they are marked on most maps and globes of the Earth. The seasons are basic to human life. They affect the foods we eat, our recreational activities, and what we wear.
Summer means shorts, swimming, baseball, strawberries and ice cream.
Fall means sweaters, football, corn, pumpkins and apples. Winter is the time for coats, basketball, skiing and oranges flown in from the tropics. Spring means light jackets, fishing, and gardening. Follow the sunlight as it travels up and down the planet. The change of seasons begins with the equinoxes.