Definition
Imaginary east-west circles drawn around the Earth parallel to the equator, used to measure latitude — the angular distance north or south of the equator. Each parallel connects all points that share the same latitude value, ranging from 0° at the equator to 90° at the North and South Poles.
Plain English
The horizontal lines on a map or globe that run side to side, parallel to the equator. They tell you how far north or south a place is.
Context Anchor
Seen when learning latitude and longitude, reading aeronautical charts, or understanding position coordinates from GPS or navigation planning.
Derivation
‘Parallel’ comes from the Greek parallelos, meaning ‘beside one another.’ These lines are called parallels because they never meet — each one runs alongside the equator at a constant distance. ‘Latitude’ comes from the Latin latitudo, meaning ‘width’ or ‘breadth,’ which fits because these lines mark how far north or south you are across the width of the Earth.
Why Pilots Care
They allow pilots to read exact latitude from charts and determine north-south position for accurate navigation.
Analogy
Think of the Earth wearing a stack of horizontal rings, like the rings on a barrel. Each ring is a parallel of latitude.
Intuition Check
Do not picture straight lines like parallel lines on paper. On Earth, parallels of latitude are circles around the globe, and they show north-south position.
Example Sentence 1
The airport sits just north of the 40th parallel of latitude, placing it at roughly 40° North.
Example Sentence 2
All parallels of latitude run parallel to the equator and are crossed at right angles by the meridians.