Where is clear air turbulence most frequently encountered?

Clear air turbulence is most frequently encountered in the vicinity of the jet stream due to the significant changes in wind speed and direction at high altitudes. The jet stream is a narrow band of strong winds in the upper levels of the atmosphere that can create turbulence as aircraft pass through or near its boundaries. This turbulence can be intensified by the interactions between the jet stream and surrounding air masses, leading to sudden and unexpected changes in altitude or aircraft movement.

Mountains can cause turbulence, but this type is typically associated with mechanical turbulence or orographic effects, rather than the clear air turbulecne associated with the jet stream. Turbulence near the earth's surface is usually related to factors such as wind shear and weather phenomena. Coastal regions may also experience turbulence, often attributed to sea breezes or weather fronts, but they are not as consistently associated with clear air turbulence as the jet stream is. Thus, the jet stream serves as the primary location where clear air turbulence is commonly encountered in flight.