What is an Isobar?

• A. A line showing wind direction
• B. A line of equal pressure on a weather map
• C. A line showing humidity
• D. A line showing temperature

Answer: (B)

An isobar is a line on a weather map that connects points with the same atmospheric pressure, usually at mean sea level. This helps reveal the pressure pattern—where highs and lows are and how quickly pressure changes across the map. The spacing between isobars indicates wind strength: close spacing means stronger winds, while wider spacing means lighter winds. Wind direction is read from wind barbs, not from the isobar itself. Other contours use different names: lines of equal temperature are isotherms, lines of equal humidity would be isohumidity, and lines of equal rainfall are isohyets. So the line of equal pressure on a weather map is the isobar.