What is Contour line?
[[File:Courbe niveau.svg|thumb|right|The bottom part of the diagram shows some contour lines with a straight line running through the location of the maximum value. The curve at the top represents the values along that straight line.]] [[Image:Contour2D.svg|right|thumb|300px|A two-dimensional contour graph of the three-dimensional surface in the above picture.]] '''Contour lines''' or '''isolines''' are used when plotting a [[function (mathematics)|function]]. All the points where the function has the same value are connected. Two well-known examples, where such lines are commonly are [[height line]]s on [[topography|topographical]] [[map]]s, and showing areas with the same [[pressure]] or [[temperature]] on weather charts. Contour lines are an application of [[level set|level sets]]. <gallery> File:Topographic_map_example.png|A map of Stove, with height lines File:IGRF_2000_magnetic_declination.gif|A map showing [[magnetism|magnetic lines]], for the year 2000 File:Meltemi.jpg|Weather diagram showing [[Meltemi winds]] over [[Greece]] and [[Turkey]] File:Temperature in Norway 2009.PNG|Temperature diagram of [[Norway]]. Areas with the same temperature have the same color File:Arctic.svg|The 10 degree isobar is commonly used to define the [[Arctic]] region </gallery> [[Category:Topography]] [[Category:Cartography]] [[Category:Statistics]]