FAA Flight Instructor Airplane (FIA)Weather and Weather ServicesHard
A meteorologist reviewing a 700-millibar constant pressure chart notices the height contour lines over a particular region are spaced very close together. What does this close spacing indicate to a pilot planning a flight through that region?
- AAn area of high pressure with no significant wind
- BA strong pressure gradient and strong winds at that altitude
- CA weak pressure gradient and generally light winds
- DAn area of surface-based temperature inversion only
Show answer & explanationAnswer & explanation
Correct answer: B. A strong pressure gradient and strong winds at that altitude
On a constant pressure chart, height contours function like isobars, representing the height of a given pressure surface. Closely spaced contours indicate a steep height gradient, corresponding to a strong pressure gradient and therefore stronger winds, similar to closely spaced isobars on a surface chart.
Why the other options are wrong
- A. Contour spacing indicates wind strength, not simply the presence of a high-pressure center.
- C. Widely spaced, not closely spaced, contours indicate a weak gradient and light winds.
- D. Constant pressure charts depict conditions at altitude, not surface-based temperature inversions.
Constant Pressure Chart
An upper-air chart depicting the height, temperature, wind, and humidity at a specified constant pressure surface (e.g., 700mb, 500mb).
- Height contours function like isobars, showing pressure surface topography
- Closely spaced contours indicate strong winds; widely spaced indicate light winds
- Commonly analyzed levels include 850, 700, 500, 300, and 200 mb
Memory trick: Tight contour lines = tight winds, like squeezing isobars together