Why does the position of sunrise along the eastern horizon change during the year?

Answer 1

Because the axis of the Earth's rotation is tilted by 23.5 degrees to the ecliptic (which is the plane of the Earth's orbit around the Sun), the Sun "appears to" rise north of the equator between March 21 and September 21, and south of the equator between September 21 and March 21. (These dates may vary a day or two either way, depending on the cycle of leap years.)

If you lived at the equator, the Sun would appear to rise due east all the time. Since you do not live on the equator, the Sun appears to rise north of east in the (northern hemisphere) spring and summer, south of east during the fall and winter. Depending on your latitude, it can be many degrees north or south of east.

Answer 2

The position of sunrise along the eastern horizon changes throughout the year due to the tilt of the Earth's axis. As the Earth orbits the sun, the angle of the sunlight hitting different parts of the Earth changes, causing the Sun to rise at different points along the horizon. This phenomenon is responsible for the changing seasons.

Answer 3

It depends on the latitude, but it's generally a sinusoidal wave. The length of the day is greatest at the summer solstice, and shortest at the winter solstice.