Sun Declination Graph / Subsolar Point Lattitude based on Day of year.

The Red Line 1) Shows the Subsolar Point - which is the position (lattitude) the sun is perceived to be directly overhead at midday with the sun striking the Earth at a 90 degree angle (based on the time of year).

The Red Line 2) Also shows the Declination of the sun, which is the angle between the rays of the sun and the Earth's equator (based on the time of year). This angle is also same as the lattitude where the sun is directly overhead at midday which is marked on the top map. 10 degree declination = 10 degree lattitude. The Red Line alternates between North and South, with the maximum declination (either North or South) taking place at the North and South Solstices, where the declination angle is at a maxiumum of 23.4 degrees North or South, shining directly on the Tropics of Cancer (23.4 N) or Capricorn (23.4 S).