Geographic Tools (Part 2)

Distortion

Necessary error resulting from trying to represent a round, nearly spherical earth on a flat plane or map.

Geographic Information System (GIS)

A computer system that stores, organizes, analyzes,

and displays geographic data.

Global Positioning System (GPS)

A system that determines the precise position of something on Earth through a series of satellites, tracking stations and receivers.

North and South Poles-

The Northernmost and Southernmost points of the Earth’s surface,

located at the 90 degree N or S latitude mark respectively.

Grid-

A man-made system of invisible lines that span the globe. This system has been used for over 2,000 years as a globally accepted reference for finding the location of a fixed position on Earth.

Latitude-

The angular distance, measured north or south from the equator, of a point on the

earth's surface, expressed in degrees.

Parallel-

Imaginary lines extending around the Earth parallel to the equator; it is used to indicate latitude.

Equator-

The imaginary great circle around the earth's surface, equidistant from the poles and perpendicular to the earth's axis of rotation. It divides the earth into the Northern Hemisphere and the Southern Hemisphere.

Longitude-

Angular distance east or west on the earth's surface, as measured, in degrees, from

the meridian of some particular place to the prime meridian at Greenwich, England.

Meridian

A circle of constant longitude passing through a given place on the earth's surface and the terrestrial poles. Also known as lines of longitude, they run from North to South.

Prime Meridian

The starting point for measuring distance both east and west around the Earth.

Separates the eastern hemisphere from the western hemisphere. The line that runs through Greenwich, England is considered the official starting line.

International Date Line-

An imaginary line on the surface of the Earth that runs from the north to the south pole and demarcates one calendar day from the next.

Map-

A representation usually on a flat surface of the whole or a part of an area.

Map Scale-

Indicates the relationship between a certain distance on the map and the distance on the ground.

Thematic Map-

A map that emphasizes a particular theme or special topic such as the average

distribution of rainfall in an area. They are different from general reference maps because they do not just show natural features like rivers, cities, political subdivisions and highways.

Statistical Map-

A special type of map in which the variation in quantity of a factor such as

rainfall, population, or crops in a geographic area is indicated.

Cartogram-

A map that is a diagram used to present statistical information. A common example

shows the countries of the world where the size of the country varies with respect to its population.

Dot Map-

A map that uses a dot to represent the number of a phenomenon found within the

boundaries of a geographic area.

Choropleth Map-

A map that uses differences in shading, coloring, or the placing of symbols

within predefined areas to indicate the average values of a property or quantity in those areas.

Isoline Map-

A map with continuous lines joining points of the same value. Examples would be

equal altitude (contour lines), temperature (isotherms), barometric pressure (isobars), wind speed (isotachs), wind direction (isogon), wind shear (isoshear), etc.

Mental Map-

A map that represents an individual person’s perception of the world.

Model

An abstraction, an imaginary situation, proposed by geographers to simulate laboratory

conditions so that they may isolate certain causal forces for detailed study.

Projection

The system used to transfer locations from Earth's surface to a flat map.

Remote Sensing-

The acquisition of data about Earth's surface from a satellite orbiting the

planet or other long-distance methods.

Time Zones-

Generally refers to any of the 24 regions on the Earth’s surface loosely divided by

longitude in which standard time is kept.