Longitude is given as an angular measurement ranging from 0° at the prime meridian to +180° eastward and −180° westward. The Greek letter λ (lambda),[3][4] is used to denote the location of a place on Earth east or west of the prime meridian.
Each degree of longitude is sub-divided into 60 minutes, each of which divided into 60 seconds. A longitude is thus specified in sexagesimal notation as 23° 27′ 30" E. For higher precision, the seconds are specified with a decimal fraction. An alternative representation uses degrees and minutes, where parts of a minute are expressed in decimal notation with a fraction, thus: 23° 27.500′ E. Degrees may also be expressed as a decimal fraction: 23.45833° E. For calculations, the angular measure may be converted to radians, so longitude may also be expressed in this manner as a signed fraction of π (pi), or an unsigned fraction of 2π.
Distance between Lines: If you divide the circumference of the earth (approximately 25,000 miles) by 360 degrees, the distance on the earth's surface for each one degree of latitude or longitude is just over 69 miles, or 111 km. Note: As you move north or south of the equator, the distance between the lines of longitude gets shorter until they actually meet at the poles. At 45 degrees N or S of the equator, one degree of longitude is about 49 miles.
Minutes and Seconds For precision purposes, degrees of longitude and latitude have been divided into minutes (') and seconds ("). There are 60 minutes in each degree. Each minute is divided into 60 seconds. Seconds can be further divided into tenths, hundredths, or even thousandths.
Absolute Location is the definitive location of a place using a recognized coordinate system. In terms of latitude and longitude, our office in Galveston, Texas, is 29°16' North, 94°49' West, marked with the red dot on the map above
Relative Location of a city or destination on the planet is its relationship to another place or nearby landmarks.