Earth's Axial Tilt: Earth's axis of rotation is tilted at an angle of approximately 23.5 degrees with respect to its orbital plane around the Sun. This tilt causes different parts of the Earth to be tilted towards or away from the Sun during its orbit.
Northern/Southern Hemisphere Tilt: During the Northern Hemisphere summer (June-July), the Northern Hemisphere is tilted towards the Sun. This means that the Sun's rays are more directly overhead in the Northern Hemisphere, resulting in a higher solar altitude and longer daylight hours. Conversely, during the Northern Hemisphere winter (December-January), the Northern Hemisphere is tilted away from the Sun, leading to a lower solar altitude and shorter daylight hours.
Solstices: The two extreme points in the Sun's path are called solstices. The summer solstice occurs around June 21st in the Northern Hemisphere, when the Sun reaches its highest point in the sky for the year. The winter solstice occurs around December 21st in the Northern Hemisphere, when the Sun reaches its lowest point in the sky for the year.
Equinoxes: Twice a year, on March 20th/21st and September 22nd/23rd, the Earth's axis is not tilted towards or away from the Sun. During these equinoxes, the Sun's rays are directly overhead at the Equator, and the daylight hours are approximately equal everywhere on Earth.
Additionally, the eccentricity of Earth's orbit around the Sun and the varying distance between Earth and the Sun throughout the year can slightly influence the Sun's altitude at midday. However, these effects are less significant compared to the impact of Earth's axial tilt.
In summary, the height of the Sun at midday changes throughout the year due to Earth's axial tilt and its orbital position around the Sun. This tilt causes the Sun's rays to be more concentrated or dispersed depending on the location and time of year, resulting in variations in solar altitude and daylight hours.
