Isobars

Source: http://xweb.geos.ed.ac.uk/~hcp/metar_analysis.html

Direct link to map: http://xweb.geos.ed.ac.uk/~hcp/metcache/metar_analysis.png

Isobars are lines that connect points of equal atmospheric pressure on weather maps. Isobars are similar to height lines on a geographical map, and they are drawn so that they can never cross each other. Meteorologists use isobars on weather maps to depict atmospheric pressure changes over an area and to make predictions concerning wind flow. This map is a moving weather map. It shows up-to-date pressures and temperatures over northern Europe.