Geographic Grid: Latitudes and Longitudes

This set of vocabulary flashcards covers key concepts, definitions, and specific coordinates related to the Geographic Grid, including latitudes, longitudes, heat zones, time calculations, and Great Circles.

Geographic Grid

The framework of criss-crossing lines of latitude and longitude on a globe or map used to pinpoint places on the earth's surface.

Eratosthenes

The Greek philosopher who first calculated the circumference of the earth and devised lines of latitude and longitude to locate places.

Latitude

The angular distance of a place north or south of the Equator, marked in degrees from $0^{\circ}$ to $90^{\circ}$.

Parallels of Latitude

Imaginary lines joining all places having the same latitude which run east to west and are parallel to the Equator and each other.

Equator

The longest line of latitude representing $0^{\circ}$, which divides the earth into the Northern and Southern Hemispheres and is the only latitude that is a Great Circle.

Tropic of Cancer

A main line of latitude located at $23\frac{1}{2}^{\circ}\text{N}$ of the Equator.

Tropic of Capricorn

A main line of latitude located at $23\frac{1}{2}^{\circ}\text{S}$ of the Equator.

Arctic Circle

A line of latitude at $66\frac{1}{2}^{\circ}\text{N}$ that marks the limit of the north polar region.

Antarctic Circle

A line of latitude at $66\frac{1}{2}^{\circ}\text{S}$ that marks the limit of the south polar region.

Absolute Location

The specific location of a place north or south of the Equator as provided by its latitude.

Torrid Zone

Also called the Tropical Zone, it is the hottest region of the earth lying between the Tropic of Cancer ($23\frac{1}{2}^{\circ}\text{N}$) and the Tropic of Capricorn ($23\frac{1}{2}^{\circ}\text{S}$).

Temperate Zones

Climatic zones with moderate temperatures located between the Tropic of Cancer and Arctic Circle in the north, and the Tropic of Capricorn and Antarctic Circle in the south.

Frigid Zones

The cold polar regions located between the Arctic Circle and the North Pole, and between the Antarctic Circle and the South Pole.

Longitude

The angular distance of a place east or west of the Prime Meridian.

Prime Meridian

The line of longitude defined as $0^{\circ}$ that passes through Greenwich near London.

Meridians of Longitude

Imaginary semicircles of equal length that run from north to south and converge at the poles.

EGA-WLS

A formula for time calculation where East-Gain-Add means adding 4 minutes for each $1^{\circ}$ east, and West-Lose-Subtract means subtracting 4 minutes for each $1^{\circ}$ west.

Local Time

The time of any place obtained by the position of the overhead sun at noon.

Standard Time

The uniform time for a region based on a central meridian, which must be divisible by $7\frac{1}{2}^{\circ}$.

Greenwich Mean Time (GMT)

The mean time fixed with reference to the Prime Meridian ($0^{\circ}$ longitude) at Greenwich.

Indian Standard Time (IST)

The standard time of India based on the central meridian of $82^{\circ}30'\text{E}$, which is 5½ hours ahead of GMT.

International Date Line (IDL)

The $180^{\circ}$ line of longitude where the date changes by exactly one day when crossed.

Great Circle

A circle on the earth's surface whose plane passes through the centre of the earth, representing the shortest route between two points.

Small Circle

Any circle on the earth's surface, such as parallels of latitude other than the Equator, whose plane does not pass through the centre of the earth.