Fundamental Geographical Concepts . Location, Latitude, and Longitude

Geographic inquiry focuses on several important questions. Where are things located on the surface of the earth? Why are things located where they are? What factors are responsible for differences between places on the earth's surface? What accounts for cultural differences between places? The fundamental concepts of geography — the concepts that distinguish the geographer's intellectual approach from those of other disciplines—have been developed in response to questions such as these.

Location, Latitude, and Longitude. Location is the most fundamental concept in human geography. In studying any event occurring on the surface of the earth, the first question asked by the geographer is simply. "Where is it?" In asking locational questions, geographers are concerned with both absolute location and relative location. The absolute location of a place is its specific position on the surface of the earth. The relative location of a place is its position compared to the locations of other places.

As the earth revolves around the sun. it rotates on its axis. The earth completes a full rotation every twenty-four hours. The axis of rotation provides a reference point for identifying absolute locations on the surface of the earth. The four cardinal directions — north, south, east and west — are defined with respect to the axis of rotation (Figure 1-3).

Figure 1-3. The Cardinal Directions and the Axis of Rotation. The four cardinal directions—north, south, east, and west—are defined on the surface of the earth by the rotation of the earth on its axis. Distances north and south are measured in degrees of latitude. Degrees of longitude measure distances east and west

The endpoints of the axis of rotation are the NorthPole and the South Pole. Movement toward the poles defines the cardinal directions of north and south. Everyother point on the earth's surface rotates around the axisevery day. The rotation of any point defines a circle onthe earth's surface. These circles are known as parallelsof latitude. Movement along parallels of latitude definesthe cardinal directions of east and west.

The equator is the parallel of latitude located midway between the two poles. The latitude of the equator is defined as 0°. The latitude of the North Pole is 90° north latitude, and that of the South Pole is 90° south latitude. The latitude of any other point on the earth's surface is the angle of arc between the equator and the poles. For example, Minneapolis and Belgrade at 45° north latitude are halfway between the equator and the North Pole. St. Petersburg (Leningrad) at 60° north latitude is two-thirds of the way from the equator to the North Pole.

Half circles that connect the geographic poles and intersect the equator at right angles are called meridians. Meridians are used to determine location east or west of a given reference meridian known as the prime meridian. Since 1884, by international agreement, the prime meridian has been established as the meridian that passes through the Royal Observatory in Greenwich. England.

Longitude is measured in degrees east or west of the prime meridian. For example, the longitude of Belgrade is 21° east of Greenwich, while that of St. Petersburg is 30° east of Greenwich. Locations in the United States are west of the prime meridian. The longitude of New York is 74° west of Greenwich. Minneapolis is 93° west of Greenwich, and Los Angeles is 118° west of Greenwich.

More precise locational information can be determined by further subdividing parallels of latitude and meridians of longitude into minutes and seconds. Each degree is divided into 60 minutes (') of angular distance, and each minute is further divided into 60 seconds ("). A more precise measure of the latitude and longitude of Minneapolis is 44° and 58' north latitude and 93° and 15' west longitude. This is customarily abbreviated as 44°58'N, 93°15'W. If the latitude and longitude of any place are known, its absolute location can be identified within a distance of about sixty feet.