What does close isobars indicate about weather?

• A. They indicate a calm day
• B. They indicate high humidity
• C. They indicate light rain only
• D. Close isobars indicate heavy winds and bad weather

Answer: (D)

The key idea is that the spacing of isobars shows how strong the horizontal pressure gradient is. When isobars are close together, the pressure changes rapidly over a short distance, which means a steep gradient. That strong gradient drives higher surface winds. Weather systems and fronts often produce tight isobars, so you’re likely to see gusty winds and more active weather—sometimes stormy conditions and rough seas.

So, close isobars signal heavy winds and unsettled or bad weather. The options about calm conditions, high humidity, or rain alone don’t align with the relationship between isobar spacing and wind strength.