FAA Sport Pilot Airplane (SPA)WeatherHard
A pilot planning a high-altitude cross-country flight reviews the winds aloft forecast and briefing materials describing a strong jet stream along the route near the tropopause. On which side of the jet stream core is clear air turbulence (CAT) most likely to be encountered?
- ADirectly beneath the jet core at low altitude, unrelated to wind shear
- BOn the equatorial (warm) side of the jet core, where wind speeds are most uniform
- CCAT is equally likely on all sides of the jet stream regardless of shear
- DOn the poleward (cold) side of the jet core, where wind shear is greatest
Show answer & explanationAnswer & explanation
Correct answer: D. On the poleward (cold) side of the jet core, where wind shear is greatest
Clear air turbulence is most commonly associated with strong wind shear found on the poleward (cold, cyclonic) side of the jet stream core, near the tropopause, where temperature and wind speed gradients are steepest.
Why the other options are wrong
- A. CAT is a high-altitude phenomenon tied to shear near the tropopause, not low-altitude.
- B. The warm/equatorial side generally has less shear and less associated turbulence.
- C. CAT is not uniformly distributed; it concentrates where shear is strongest.
Clear Air Turbulence (CAT) and Jet Stream
CAT is turbulence occurring in clear skies, most frequently found near the tropopause on the poleward (cold) side of a jet stream core where wind shear is strongest.
- Associated with strong wind shear near the tropopause
- Most likely on the cold/poleward side of jet core
- Cannot be seen visually, detected by PIREPs or forecast shear zones
Memory trick: Cold side, sharp shear, that's where CAT will appear.