The tropopause is a layer in the atmosphere that often harbors turbulence. On which flight is crossing the tropopause most likely to cause turbulence?

The tropopause is a layer in the atmosphere that often harbors turbulence. On which flight is crossing the tropopause most likely to cause turbulence?

• A. JFK to SFO in July
• B. LAX to ORD in February
• C. KBOS to KSEA in January
• D. BOS to IAD in March

Answer: (C)

High-level wind shear near the tropopause is what often triggers turbulence, and the strongest, most persistent upper-level winds at mid to high latitudes come from the polar jet stream. That jet sits near the boundary between the troposphere and the stratosphere, so flights that cross these northern jet streams during winter have the greatest chance of seeing turbulence when crossing the tropopause. The route from Boston Logan to Seattle-Tacoma in January best fits this scenario. In January, the polar jet is powerful and tends to lie across mid-latitude North America, so a long westbound flight from the East Coast to the Pacific Northwest will pass through these strong upper-level wind regions near the tropopause, increasing the likelihood of turbulence during the crossing. The other options involve routes or seasons where the upper-level jet is weaker or the flight path is less aligned with the strongest jet streams, making tropopause-crossing turbulence less likely.

High-level wind shear near the tropopause is what often triggers turbulence, and the strongest, most persistent upper-level winds at mid to high latitudes come from the polar jet stream. That jet sits near the boundary between the troposphere and the stratosphere, so flights that cross these northern jet streams during winter have the greatest chance of seeing turbulence when crossing the tropopause.

The route from Boston Logan to Seattle-Tacoma in January best fits this scenario. In January, the polar jet is powerful and tends to lie across mid-latitude North America, so a long westbound flight from the East Coast to the Pacific Northwest will pass through these strong upper-level wind regions near the tropopause, increasing the likelihood of turbulence during the crossing.

The other options involve routes or seasons where the upper-level jet is weaker or the flight path is less aligned with the strongest jet streams, making tropopause-crossing turbulence less likely.