Where is a common location for clear air turbulence?

Clear air turbulence is often found in areas of strong wind shear, particularly near jet streams. The location specified by the correct answer, in an upper trough on the polar side of a jet stream, is ideal due to the dynamic weather conditions that occur at these latitudes. As air masses with different temperatures and velocities interact in these regions, the resulting instability can lead to turbulence.

Jet streams are typically situated at higher altitudes and are characterized by swift winds that can change drastically over small distances, especially when associated with troughs and ridges. In this context, the upper trough creates a scenario where colder air collides with warmer, more turbulent air, which is conducive to the formation of clear air turbulence.

Other choices also present possibilities for turbulence but in different contexts. For instance, while turbulence can occur near thunderstorms, it is more likely to be associated with convective turbulence rather than clear air turbulence. Similarly, being beneath a warm front or within an upper ridge does not typically present the same level of instability or wind shear as found in the vicinity of jet streams, making those locations less likely to produce the specific type of turbulence referred to here.