The Sumerians are thought to have formed the first human civilization in world history. They lived in southern Mesopotamia, between the Tigris and Euphrates Rivers in the Middle East. Cradle of Civilization. Many historians think that cities and towns were first formed in Sumer around 5000 BC.
At noon, on March 21 and September 23rd are the vernal and autumnal equinoxes. The sun is directly overhead at the equator at these times. On June 22nd is the summer solstice, in the Northern Hemisphere. The sun is at the 23.5 degrees Northern latitude.
At winter solstice (21 December), the sun's rays make an angle of -23Â° 27' to the equatorial plane. The beam radiation is approximately perpendicular to the Tropic of Capricorn (20Â°30'S). In the northern hemisphere, the days are at there shortest and the solar altitude at noon has its lowest values.he horizon is represented by the outermost circle, at the periphery. The altitude of the sun above the horizon is read on the various concentric circles, from 0 to 90 degrees. The angle of azimuth is written on the periphery (0 degrees is south, east and west are 90 degrees on either side).