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. The September autumnal equinox is the day the sunlight crosses the equator as it moves south. It is the beginning of fall in the north. In America, this is when you clean up your ice skates and make sure your ski boots still fit.