The seasons are created as Earth spins on its axis and moves in an elliptical orbit around the sun. This orbit takes 365 days to complete, and is the reason that humans experience the seasons: winter, spring, summer and fall. However, other factors influence the seasons as well.
Earth sits at a tilt of 22.5 degrees, also known as an axis. Earth's tilt influences the seasons as Earth travels in orbit around the sun. Earth’s axis causes the Northern Hemisphere to point toward the sun during the summer months, beginning in June, and away from the sun during the winter months, beginning in December. When Earth is pointing at a 90-degree angle, toward or away from the sun, the Northern Hemisphere experiences spring and fall seasons. Seasons in the Southern Hemisphere are the opposite; therefore, June marks the beginning of the winter months, while December marks the beginning of the summer months.
Sunlight influences the seasons, particularly the sun's position and Earth's surface that reflects the light. During the summer months, the sun is positioned highest overhead; the maximum amount of heat is transferred to the ground. Conversely, in the winter months, when the sun is positioned lower in the sky, the ground absorbs less heat, creating colder climates. Earth's surface also plays a part in influencing the seasons by allowing the atmosphere to absorb or lose heat. For example, areas that are darker with dense vegetation can absorb more heat during the summer months, while areas with ice and snow reflect and lose heat.
Elevation also influences the seasons. Elevation is the reason some areas may remain cold, even during the summer months. Higher elevations are typically colder, with the highest altitudes having a harder time sustaining life. The winter months at high elevations are the harshest winters of all, with continual storms.
As the seasons change, so do the wind patterns. In the winter months, when the sunlight is less intense, cold air begins to collect in the Northern Hemisphere. Conversely, in the summer months, warm air and sunlight heat up the Northern Hemisphere. Wind patterns change with the seasons, moving north or south.
Climate change influences the seasons. As warming trends sweep the globe, humans are left to wonder how much of these trends are natural and how much humans influence. Over time, Earth goes through warming and cooling trends. While these trends are natural, the rate at which current warming trends are occurring have led the scientific community to believe that global warming is due to human influence. The clearing of forests and the burning of fossil fuels are leading to a warming trend that is affecting the balance of the seasons.