Causes of Seasons

In the fall, some trees lose their leaves and the temperature begins to drop. In the
winter, we have the coldest temperatures, winter storms, and less hours of daylight. In
the spring, temperature begins to rise, causing snow to melt. Often there is rainfall, and
plants begin to grow and sprout. In the summer, we have the warmest temperatures,
sometimes heat waves, and the most hours of daylight.

The equator is an imaginary line that divides Earth into two halves called the
Northern Hemisphere and the Southern Hemisphere. The Northern Hemisphere lies
above or to the north of the equator, whereas the Southern Hemisphere lies to the south
or below the equator

Earth’s axis is an imaginary line around which Earth rotates. The points where the
axis intersects with the surface of Earth are the North Pole and the South Pole. Earth’s
axis is tilted 23.5° to its plane of orbit.

Earth’s orbit is an almost circular, repeating path around the Sun. Earth is held in its
orbit by gravity. The force of gravity is balanced between Earth and the Sun to keep
Earth on its cycle of orbiting the Sun once every 365 days.

Drawings should include the Sun and Earth and show Earth tilted on its axis toward
the Sun (if representing summer in the Northern Hemisphere) or away (if representing
winter).

Drawings should include the Sun and Earth and show Earth tilted on its axis toward
the Sun (if representing winter in the Southern Hemisphere) or away (if representing
summer).

Latitude are the imaginary lines that measure the distance north or south of the equator. The equator divides Earth equally into two hemispheres and is found at 0° latitude. The Arctic Circle is found at 66.5°N, and the Antarctic Circle is found at 66.5°S. The Tropic of Cancer is found at 23.5°N and the Tropic of Capricorn is found at 23.5°S.

The further you travel north or south of the equator, the more extreme the differences are between the seasons, including temperatures and hours of daylight. At the equator, there are very few differences between the seasons, with warmer temperatures all year long and hours of daylight always being 12 hours a day. The regions north of the equator experience winter in December and summer in June, whereas the opposite is true for regions south of the equator.

In the summer, light intensity is higher than in the winter.

When the angle of light that hits the surface of Earth is closer to 90°, the area is experiencing summer and warmer temperatures. In the winter, the angle at which light hits the surface of Earth is much smaller than 90°, causing colder temperatures in that area.

When the Northern and Southern Hemispheres are pointing toward the Sun, that region experiences more daylight hours. When the Northern and Southern Hemispheres are pointing away from the Sun, that region experiences fewer daylight hours.

Because every location has a unique latitude, the number of hours of daylight varies between the two regions. The larger the degree of latitude, the longer the hours of daylight.