LATITUDE

The principles of lines of latitude

To fix the position of places on the globe, imaginary lines of reference are used. They are called lines of latitude and longitude.

Lines of latitude circle the Earth parallel to the Equator. Because the Earth is a sphere, distances between two lines

of latitude are measured in angular not linear units, that is, in degrees, minutes, and seconds.

The Equator is an imaginary line round the circumference of the Earth, midway between the North and South Poles.

It is latitude 0°. Lines of latitude circle the Earth parallel to the Equator. These lines are also known as parallels or small circles.

Every line of latitude is a circle and contains 360°.

There are 60 minutes (indicated by ') in a degree, and 60 seconds (indicated by ") in a minute.

Starting from the Equator, lines of latitude are marked off at 1°-intervals North and South up to 90°.

The North Pole is 90°N and the South Pole is 90°S.

One degree of latitude is about 60 nautical (sea or air) miles or 69 land or statute miles (111 km),

except near the poles where, due to flattening of the Earth, it is a little more.

Measurement

The latitude of a location is also known as its geodetic, geographical,

or true latitude.

Latitude is a measure of the angle that the perpendicular (line at right-angles)

from that location on the Earth's surface makes with the plane of the Equator.

Measurements of latitude are given as x°y'z" North or South.

Perpendiculars from the Earth's surface do not always intersect the

center of the globe because the Earth is not completely spherical

it is flattened at the poles.

In the Northern Hemisphere, you can calculate roughly your latitude at a place by pointing one arm at the

North Star and the other at the horizon. The angle between your arms is roughly the latitude where you are.

a Northern Hemisphere

b Southern Hemisphere

c plane of the Equator (0°)

d North Pole

LONGITUDE

The principles of lines of longitude

To fix the position of places on the globe, imaginary lines of reference are used.

They are called lines of latitude and longitude.

Lines of longitude all run through the North and South Poles and circle the Earth.

Because the Earth is a sphere, distances between two lines of longitude are measured in

angular not linear units, that is, in degrees, minutes, and seconds.

The starting point for lines of longitude is the Observatory at Greenwich, London, in England.

It is longitude 0° and is known as the Prime Meridian. Lines of longitude are also known as meridians.

Every line of longitude is a circle and contains 360°.

There are 60 minutes (indicated by ') in a degree, and 60 seconds (indicated by ") in a minute.

Starting from the Greenwich Meridian, lines of longitude are marked off at 1°-intervals East and West up to 180°.

The direction in which the Earth rotates is called "East" and the opposite direction is "West."

Lines of longitude are perpendicular (at right-angles) to lines of latitude.

One degree of longitude varies from 0 miles (0 km) at the Poles to 69 miles (111 km) at the Equator.

Because the Earth spins on its axis once every 24 hours, all 360 degrees of longitude pass beneath the Sun each day.

Therefore one hour of time is considered equivalent to 15° of longitude. The world's time zones are based on this.

Measurement

The longitude of a location is a measure of the angle that its meridian makes with the Greenwich Meridian

at the centre of the Earth and in the plane of the Equator.

Measurements of longitude are given as x°y'z" East or West.

a western hemisphere

b eastern hemisphere

c plane of the Greenwich meridian/International Date line (0°/360°)