In a high-level jetstream, the worst turbulence is found on which side of the jet core?

• A. Poleward side underneath jet core
• B. Equatorward side above jet core
• C. Directly under the core’s edge
• D. Away from the jet stream entirely

Answer: (A)

Turbulence around a jet stream mainly arises from wind shear—the change in wind speed and direction over a short distance. The strongest shear on a high-level jet tends to occur on the poleward side of the jet core, and when you’re just below the core in that zone, the contrast between fast air aloft and slower air below creates the most unstable conditions. That combination promotes mixing and rotor-like disturbances, producing the worst turbulence there.

The other zones don’t typically experience the same intensity of shear: the equatorward side above the jet core often has less severe shear, being relatively more stable; right under the core’s edge is close to the core where turbulence can occur but is generally not as intense as on the poleward flank; and being far away from the jet implies minimal wind shear and much weaker turbulence.