What is the primary cause of the seasons on Earth?

The primary cause of the seasons on Earth is the tilt of the Earth's axis. The Earth is tilted at an angle of approximately 23.5 degrees relative to its orbit around the Sun. This axial tilt means that as the Earth orbits the Sun throughout the year, different parts of the Earth receive varying amounts of sunlight at different times.

During summer in one hemisphere, that part of the Earth is tilted towards the Sun, resulting in more direct sunlight and longer days. In contrast, during winter, that hemisphere is tilted away from the Sun, which leads to less direct sunlight and shorter days. This variation in sunlight intensity and duration causes the diverse seasonal changes experienced in different regions of the Earth.

Factors such as distance from the Sun, the amount of water in the atmosphere, and variations in solar wind do influence climate and weather patterns, but they do not directly affect the seasonal changes that arise from the axial tilt.