Definition
Latitude and longitude are the two coordinates used to describe any position on the surface of the Earth. Latitude is measured in degrees north or south of the Equator, from 0° at the Equator to 90° at each pole. Longitude is measured in degrees east or west of the Prime Meridian (which runs through Greenwich, England), from 0° to 180°. On a chart, lines of latitude are called parallels because they run east–west parallel to the Equator, and lines of longitude are called meridians because they run north–south from pole to pole.
Plain English
It’s the grid system used to pinpoint exactly where something is on Earth. Latitude tells you how far north or south you are; longitude tells you how far east or west. The east–west lines on a chart are parallels (latitude); the north–south lines are meridians (longitude).
Context Anchor
Seen on aeronautical charts, airport location data, navigation displays, and position reports.
Derivation
Latitude comes from the Latin latitudo, meaning ‘breadth’ or ‘width,’ which fits because latitude lines stretch east–west across the width of the globe. Longitude comes from the Latin longitudo, meaning ‘length,’ matching the long north–south lines that run from pole to pole. Meridian comes from the Latin meridies, meaning ‘midday,’ because the sun crosses any given meridian at local noon. Parallel simply reflects that those lines never cross — they stay parallel to the Equator.
Why Pilots Care
Pilots use latitude and longitude to determine exact position, navigate accurately, and comply with air traffic control routing.
Analogy
Think of it like the rows and columns on a giant spreadsheet wrapped around the Earth. Latitude is the row number; longitude is the column. Give both, and you have one unique cell — one unique spot on the planet.
Grounding Statement
If you can picture a grid wrapped around the globe, latitude and longitude are the lines that let you name any point on that grid.
Intuition Check
Do not think of “parallel” here as just any two lines that never meet on a flat page. In this context, parallels are latitude lines around the Earth, and meridians are longitude lines that meet at the poles.
Example Sentence 1
The pilot confirmed the destination airport’s latitude and longitude before loading it into the GPS.
Example Sentence 2
Meridians converge at the poles, which is why longitude changes rapidly near the North Pole.