Because the axis of earth is titled, and the fact that earth rotates in its orbit around the sun, a wave like character is introduced to how the days change over the period of a year.
Depending on your position on the planet, you will experience that yesterday the sun rose earlier ór it rose later (and more to the right or left) than today. If it rose more to the left yesterday, the arc of the sun is declining and you are going towards mid-winter. If the sun rose more to the right yesterday, the arc is increasing and you are heading for the middle of the solar year.
You would experience the results of the suns impact on nature around you as its daily rising spot and maximum altitude change over time.