Leveyssuunta

Leveyssuunta is a term used in geography and cartography to describe the east–west direction. It denotes the horizontal axis of direction, in contrast to pituussuunta, which refers to the north–south direction. On most maps, leveyssuunta aligns with lines of latitude (leveyspiirit), which run east–west across the globe. In practice, moving in leveyssuunta means changing longitude (pituusaste) while latitude (leveysaste) remains approximately constant.

In navigation and planning, leveyssuunta is used to describe legs of travel that head toward the east or west. In grid-based coordinate systems, the east–west axis is associated with eastings, while the north–south axis corresponds to northings. The distance represented by one degree of longitude varies with latitude: it is largest at the equator and decreases toward the poles.

Example: A route from 60°N, 25°E to 60°N, 30°E is a movement in leveyssuunta (eastward) along the 60th parallel.

Notes: Leveyssuunta is a directional concept, whereas leveyspiiri (latitude) and pituuspiiri (longitude) are geographic lines. Together, they define positions on the Earth and underpin map projections and coordinate systems.