“Earth's tilted axis causes the seasons. Throughout the year, different parts of Earth receive the Sun's most direct rays. When the North Pole tilts toward the Sun, it is summer in the Northern Hemisphere. When the South Pole tilts toward the Sun, it is winter in the Northern Hemisphere.”
Winter forms because Earth's axis is tilted at about 23.5 degrees. When a hemisphere tilts away from the Sun, sunlight reaches it at a lower angle. This spreads the Sun’s energy over a larger area and reduces heating.
As a result, temperatures decrease, days become shorter, and weather patterns shift. In many regions, winter brings colder air masses, frost, snow, and ice.