Distance from the equator is measured in degrees of latitude. Latitude is the angular distance north or south of the equator, ranging from 0° at the equator to 90° at the poles. Lines of latitude run east–west and are parallel to one another.

Latitude strongly influences climate because it determines the angle of incoming solar radiation. Tropical, temperate, and polar zones are defined primarily by latitude. One degree of latitude equals approximately 111 kilometers.

Together with longitude, latitude provides a unique coordinate for every location on Earth. GPS receivers and maps use the system constantly. The concept is simple yet fundamental to navigation, climate science, and the description of any place on the planet.

• Angular distance north or south of the equator
• Ranges from 0° to 90°
• Lines run parallel east–west
• Major control on climate