Why does the sun appear to remain lower in the sky on the winter solstice than the rest of the year?
The apparent lower position of the sun in the sky during the winter solstice is primarily due to the tilt of the Earth's axis. The Earth's axis is tilted about 23.5 degrees in relation to its orbital plane around the sun. During the winter solstice, which occurs around December 21st in the Northern Hemisphere, the North Pole is tilted the furthest away from the sun.
As a result, the sun's rays hit the Northern Hemisphere at a slanted angle. This means that sunlight has to pass through a thicker portion of the atmosphere to reach the surface. The Earth's atmosphere scatters shorter wavelengths of light (blue and green) more than longer wavelengths (red and orange). Consequently, the shorter wavelengths are scattered away, leaving behind predominantly longer wavelengths that appear warmer in color.
The scattering of shorter wavelengths and the increased thickness of the atmosphere during the winter solstice leads to the sun appearing lower in the sky. The sunlight has to travel through a greater distance in the atmosphere, which also causes some additional absorption and dispersion of the shorter wavelengths, resulting in the sun appearing lower, dimmer, and less intense compared to other times of the year.