Chapter 2: Geographic Grid - Latitudes and Longitudes

Latitude

The angular distance of a place north or south of the equator, measured in degrees.

Longitude

The angular distance of a place east or west from the Prime Meridian, also measured in degrees.

Prime Meridian

The line of reference for measuring east-west distances, considered as 0° longitude.

Absolute Location

The exact coordinate on the Earth, described in terms of latitude and longitude.

Relative Location

The location of a place in relation to another place.

Equator

The imaginary line at 0° latitude which lies modway between the poles.

Tropic of Cancer

The parallel of latitude at 23½° N of the equator.

Tropic of Capricorn

The parallel of latitude at 23½° S of the equator.

Arctic Circle

The parallel of latitude at 66½° N of the equator.

Antarctic Circle

The parallel of latitude at 66½° S of the equator.

Great Circle

A circle on the Earth's surface that divides the Earth into two equal halves, such as the Equator.

Heat Zones

Regions categorized based on temperature: Frigid, Temperate, and Torrid Zones.

Frigid Zone

The coldest climatic zone, located at high latitudes near the poles.

Temperate Zone

The moderate climatic zone between the Frigid and Torrid Zones.

Torrid Zone

The hottest climatic zone, found between the Tropic of Cancer and the Tropic of Capricorn.

International Date Line

An imaginary line at approximately 180° longitude where the date changes by one day.

Time Zones

Regions of the Earth divided based on longitudinal extent, each representing one hour of time.

GMT (Greenwich Mean Time)

The mean solar time at the Royal Observatory in Greenwich, London, used as a reference for time worldwide.

Local Time

Time based on the position of the sun relative to a particular locality, tied to specific meridians.

Standard Time

A uniform time adopted within a region or country, linked to the GMT.

Indian Standard Time (IST)

The standard meridian time for India, which is 5 hours and 30 minutes ahead of UTC.

Geographic Grid

The system of lines of latitude and longitude used to determine absolute and relative locations.

Meridians

Lines of longitude that run from the north pole to south pole and converge at the poles.

Hemispheres

The two halves of the Earth, divided by the Equator (Northern and Southern) and by the Prime Meridian (Eastern and Western).

Calculation of Time

Using the rotation of the Earth, which takes 24 hours to complete a full 360°, to determine local time based on longitude.

1° Latitude

Is approximately equal to 111 kilometers or 69 miles.

Axis

The imaginary line around which the Earth rotates.

Distance Between Latitudes

Remains constant as they are parallel; 1° is equal to about 111 km.

Distance Between Longitudes

Decreases toward the poles as they converge.

Navigation

The process of determining and planning the route or course to be followed.

Aviation

The design, development, production, operation, and use of aircraft.

Cultural effect of Time Zones

Time zones can create confusion in scheduling and communication, especially in large countries.

Line of Longitude

The imaginary line drawn from the north pole to the south pole is known as meridians of longitude/ line of longitude. Meridians converge at poles.these lines join all the place having same angular distance measured in degrees along the equator east or west of prime meridian.

Line of Latitude

The imaginary line which joins places having the same angular distance north or south of the Equator.

Geographic Grid

It is the network of parallels of latitudes and meridians of longitude drawn on a globe or a map .

Great Circle

A circle on the Earth's surface that divides the Earth into two equal halves, such as the Equator.

Small Circle

A circle on the Earth's surface that does not divide the Earth into equal halves; examples include circles of latitude that are not the Equator.

Usage of Small Circle

Small circles are used for navigation, aeronautical charts, and defining specific regions on Earth's surface, though they don't divide the Earth into equal halves.

Small Circle Example

An example of a small circle is the Tropics of Cancer and Capricorn, which do not divide the Earth into equal halves like the Equator does.

Great Circle vs. Small Circle

Great circles, like the Equator, divide the Earth into equal halves, while small circles are any other circles of latitude that do not.

Implications of Small Circles

Small circles help in understanding geographic locations, climate zones, and navigation over uneven terrains.

Why are the lines of latitude called parallels of latitude ?

Because all lines of latitude are circles parallel to the Equator.

Why is the torrid zone an area of low pressure?

Because it receives vertical or almost vertical rays of th Sun throughout the year.

Why are lines of longitude called Meridians?

Because all places along the same meridian of longitude experience noon or mid day at the same time.