Isobars are lines of equal pressure.

• A. Lines of equal height
• B. Lines of equal temperature
• C. Lines of equal pressure
• D. Lines of equal wind speed

Answer: (C)

Isobars are lines that connect points with the same atmospheric pressure on a weather map. They don’t map height, temperature, or wind speed themselves—that would be lines of equal height (geopotential height), equal temperature (isotherms), or equal wind speed (isotachs). The spacing of isobars shows how strong the pressure gradient is: close isobars mean a steep gradient and stronger winds, while wide-spaced isobars indicate a gentler gradient and lighter winds. Winds tend to flow parallel to isobars because of the balance between pressure gradient and the Coriolis effect, circling lows counterclockwise and highs clockwise in the Northern Hemisphere.