In what circumstance are iso bars closely spaced?

When iso bars, or isobars, are closely spaced, it indicates a strong pressure gradient. This strong pressure gradient typically signals that there is a significant difference in atmospheric pressure over a small distance. As a result, this condition generally leads to increased wind speeds, as air moves from areas of high pressure to areas of low pressure more rapidly when the pressure difference is pronounced.

In this context, the situation is critical for pilots, as understanding wind patterns and weather systems is essential for safe flight operations. A strong pressure gradient can lead to variable wind conditions that may affect flight performance, requiring pilots to be aware and prepared for potential changes.

Other circumstances such as minimal wind suggest a weak pressure gradient, while low pressure systems do not necessarily mean closely spaced isobars unless they are also accompanied by a strong gradient. Stability in weather typically correlates with more evenly spaced isobars, indicating gradual changes in pressure rather than sharp gradients.