What phenomenon is responsible for the changing seasons on Earth?

The phenomenon that is primarily responsible for the changing seasons on Earth is the tilt of Earth's axis. Earth's axis is tilted at an angle of approximately 23.5 degrees relative to its orbital plane around the Sun. This axial tilt causes different parts of the Earth to receive varying amounts of sunlight throughout the year.

As Earth orbits the Sun, the northern and southern hemispheres tilt towards and away from the Sun at different times of the year. During the summer solstice, for instance, the North Pole is tilted closest to the Sun, resulting in longer daylight hours and warmer temperatures in the northern hemisphere. Conversely, during the winter solstice, the North Pole is tilted away from the Sun, leading to shorter days and colder temperatures in the same hemisphere.

This variation in sunlight and temperature across different regions is what creates the four distinct seasons: spring, summer, autumn, and winter. While Earth's rotation contributes to the day-night cycle and revolutions around the Sun correlate with the length of the year, it is the axial tilt that directly influences seasonal changes in temperature and daylight. Changes in atmospheric pressure are not a primary factor in the seasonal cycle but can affect weather patterns within the established seasons.