What do closely spaced isobars on a weather map indicate?

Closely spaced isobars on a weather map indicate strong pressure gradients. When isobars are close together, this means that there is a significant change in atmospheric pressure over a short distance. A strong pressure gradient is a key factor in generating wind; the greater the difference in pressure over a given distance, the stronger the winds will be as air moves from high-pressure areas toward low-pressure areas in an attempt to equalize the pressure.

In contrast, weak pressure gradients are represented by isobars that are spaced further apart, leading to lighter winds. Fair weather is not directly indicated by the spacing of isobars; it can occur with varying pressure configurations. Additionally, while no wind would occur in a situation where there is very little difference in pressure across a region, this is not depicted by closely spaced isobars, which inherently suggest active wind patterns.