FAA Aircraft Dispatcher (ADX)MeteorologyHard
A dispatcher analyzing a 500 mb constant pressure chart notices that the height contour lines over the planned route are packed very closely together, in contrast to a widely spaced pattern the previous day. What does this tightly packed contour pattern indicate?
- AA weakening pressure gradient and lighter winds at that flight level
- BA region of increasing atmospheric stability with reduced turbulence potential
- CAn area of surface high pressure extending upward through the flight level
- DA stronger height gradient corresponding to stronger winds, likely near the jet stream core
Show answer & explanationAnswer & explanation
Correct answer: D. A stronger height gradient corresponding to stronger winds, likely near the jet stream core
On a constant pressure chart, contour lines represent lines of equal height for that pressure surface, analogous to isobars on a surface chart. Closely spaced contours indicate a strong height gradient, which corresponds to strong geostrophic winds; this pattern is commonly found near the jet stream core.
Why the other options are wrong
- A. Closely spaced contours indicate a stronger, not weaker, gradient and stronger winds.
- B. Strong height gradients are often associated with increased wind shear and turbulence, not reduced turbulence.
- C. Constant pressure charts show height patterns aloft, not directly surface pressure systems.
Constant Pressure Chart Contours
Lines on a constant pressure chart connecting points of equal height for a given pressure surface (e.g., 500 mb); closely spaced contours indicate strong winds, similar to isobars on a surface chart.
- Contour spacing is inversely related to wind speed
- Tightly packed contours indicate the jet stream core
- Used to identify troughs, ridges, and wind patterns aloft
Memory trick: Tight lines, tight winds — jet stream squeezes through the gap.