Final answer:
Winter has shorter days because the Sun's path across the sky is shortest, and it has a lower solar altitude as the rays of the Sun hit the Earth at a more oblique angle than in summer.
Step-by-step explanation:
During winter, the days are shorter and the solar altitude is lower. This is because of the Earth's tilt and its orbit around the Sun. The 23.5° tilt of Earth's axis results in different angles at which sunlight hits the planet's surface. In winter, the Sun takes a shorter path across the sky which means there are fewer hours of daylight. Moreover, as the Sun is lower in the sky, its rays spread out over a larger area, weakening the intensity of the sunlight, and thus the heat received is less effective.
Figure 4.6 illustrates how in winter, the Sun's rays are not as direct as they are in summer. The winter solstice, occurring around December 21st in the Northern Hemisphere, marks the day with the shortest daylight hours and longest night. It also represents the time when the Sun is at its lowest elevation in the sky.