Baroclinic Instability Questions and Answers

Answer: A

Cyclostrophic balance describes a tornado or dust devil, in which the Coriolis force is negligible, and has no place in the life cycle of a synoptic scale baroclinic eddy. The other three are successive stages of that cycle. The scale separation between the two regimes is enormous, and keeping the vocabulary of each apart avoids a good deal of confusion.

Answer: B

A strong zonal jet corresponds to the positive phase of the Northern Annular Mode, with the storm track directed towards northern Europe and a rapid succession of depressions bringing mild wet conditions. Cold dry conditions accompany the blocked negative phase instead. Stationary systems require blocking, which is exactly what a strong zonal flow prevents.

Answer: C

A storm track is identified objectively as a band of maximum bandpass filtered variance, running northeastward across the Atlantic and Pacific in the northern hemisphere. The jet stream and polar front are closely associated features of the same baroclinic zone, and the surf zone belongs to the stratosphere. The three tropospheric features move together as the season changes. Working one numerical case through both cases side by side fixes the distinction better than any rule of thumb.

Answer: D

Baroclinic growth converts available potential energy into eddy kinetic energy, barotropic decay returns eddy kinetic energy to the mean flow, and the mature stage between them shows little net conversion. Following the energy through the cycle, alongside the changing tilt of the disturbance, gives a complete and compact account of the life of a mid-latitude cyclone. Reading the definition literally, rather than recalling a formula, is the reliable route through questions of this shape.