Considering the physical map of the hemisphere, especially pay attention to the Degree mesh. It is known to be formed by meridians and parallels. Meridian - that imaginary line formed by the earth's surface plane of the section that passes through the Earth's axis. Parallels - is an imaginary line that formed by the earth's surface-sectional plane perpendicular (at an angle 90 °) to the earth's axis. And the meridians and parallels are imaginary lines, so the area can not see them. However, marked on a map or globe and play an important role. In addition, we are determines how often we hold these lines, depending on the scope and purpose of a map or globe. It is easy to see that all meridians are the same among themselves, because they connect the same points - the poles. Parallels unlike meridians - all different to each other. Farther from the pole, so they will be longer. The biggest parallel is the equator - a line equidistant from the poles. At its equator almost as long as any of the meridian, about 40 000 km.
With parallels determine latitude anywhere. Latitude - is the angle between the equator and the line that passes through a point to the center of the Earth. Since for any point you can draw a parallel, then to determine its latitude in degrees is enough to calculate the angular distance from the equator (it is the beginning point of latitude) to parallel this point. Equator divides the globe into two hemispheres - North and South. Latitude also is North (abbreviated Mon. Sh.) And southern (pd. Rd.). Latitude Equator - 0 °. Geographic poles are latitude 90 °.
Longitude point you to set the meridians. Geographic - is the angle between the plane of the prime meridian and the meridian of this point. The original adopted meridian passing through the Astronomical Observatory in the town of Greenwich, near the capital of Great Britain - London. This is the Prime Meridian (longitude, it is 0 °) or Greenwich. Greenwich meridian divides the globe into western and eastern hemispheres. Longitude are counting on the west and east of the prime meridian, so also is the western longitude (ZD) and Eastern (SD), and can not exceed 180 °.
A degree in any of the meridians meet, approximately 111.3 km area. The same situation is at the equator. On the other parallels the distance on the ground, which corresponds to 1 ° on the map, decreases in the direction of the equator to the poles. So the length of one degree arc parallels 10 ° is 109.6 km, the parallel 50 ° (approximate latitude of Kyiv and Kharkiv) - 71.7 km.
Geographic address any of the world is its geographic coordinates, which represent the latitude and longitude expressed in degrees. Interestingly, there are two specific points that have only latitude and longitude do not have. This - geographical poles. Carefully look at the map of the hemispheres and think what is wrong?