Meteorology and Geography

18. Diagrammatic representation of latitude and longitude

Latitude and Longitude
To determine the location of a position on the earth’s surface, we use a grid of reference lines that are superimposed on the earth’s surface and cross at right angles. These grid lines are called lines of latitude and longitude. Some lines of latitude and longitude have great significance in geographical studies.

Latitude: The angular distance of any place north or the south of the equator is called the latitude of that place. The lines of latitude are called parallels. The equator is marked at 0˚ latitude and other latitude lines are drawn around the earth parallel to the equator, northward to 90˚ N or the North Pole and southward to 90˚ S or the South Pole. The parallel of 0˚ is called the equator; those of 23.5˚ N and S are known as the tropics of Cancer and Capricorn respectively and the 66.5 ˚N and S are known as the Arctic and Antarctic circles respectively.

Characteristics of latitude
1. Latitudes are parallel to one another and hence are called parallels.
2. They always remain equal distance apart and along true east-west.
3. All parallels except the equator are small circles.
4. The latitudes are expressed in degrees, minutes and seconds, e.g. 23˚ 5′ 23"

Longitude: The angular distance of any place east or west of the Prime Meridian is called the longitude of that place. Lines of the longitude are called meridians. Among the longitudes, the 0˚ or the meridian of Greenwich is known as the prime meridian and the opposite it on the globe i.e. the 180˚ longitude is called the International Date Line. It passes through the central Pacific Ocean. All longitude lines form great circles. Only the equator is a great circle of latitude. Any circle at the earth’s surface with its center at the earth’s center is a great circle.

Characteristics of Longitudes
1. All meridians run in a true north-south direction.
2. Meridians spaced farthest apart at the equator and converge at the poles.
3. All longitude lines form great circle.