Adiabatic Processes and Lapse Rates Questions and Answers

Answer: B

The theory treats the storm as a Carnot engine drawing enthalpy from the warm ocean and rejecting heat at the cold outflow temperature, with the intensity set by the exchange coefficients and the air sea disequilibrium. Shear and rotation determine whether a storm can organise but not its thermodynamic ceiling. The theory gives an upper bound that few storms actually attain. Most errors here come from carrying a result across from a neighbouring case where it does not hold.

Answer: C

Shear tilts and ventilates the storm, importing low entropy air into the core and preventing the warm core structure from being maintained. Most storms fall well short of their potential intensity for this reason. The other factors listed are genuine requirements for genesis rather than constraints on the intensity of an existing storm.

Answer: D

Evaporation from the warm ocean supplies the latent heat that drives the storm, and the enthalpy flux increases with wind speed, which is the positive feedback that allows intensification. The cold outflow at the tropopause is where heat is rejected, completing the cycle. Mid-level dry air is an obstacle rather than a source, and stratospheric penetration is incidental. Checking the units of each quantity catches a wrong formula before the arithmetic begins.

Answer: A

The enthalpy flux from the ocean increases with wind speed, so a strengthening storm draws more energy from the surface and strengthens further, which is the WISHE feedback. Ocean cooling by mixing does act as a brake and is why slow moving storms weaken over their own cold wake. Frictional dissipation is a loss rather than a gain despite warming the air. The shared properties explain why these belong to one family, and the differences explain why more than one exists.

Answer: B

Strong winds mix cold water up from beneath the thermocline, cooling the surface by several kelvin and reducing the enthalpy flux, and a slow moving storm sits over its own cold wake. Deep warm layers and warm core eddies suppress this effect and are associated with rapid intensification. Salinity matters through its effect on mixing but is a secondary influence. Framing the question as which quantity the change acts upon makes the answer follow without calculation.

Answer: C

Because the saturation vapour pressure curve is convex, a mixture of two saturated samples at different temperatures is supersaturated and condensation occurs. This is why the breath condenses on a cold day and why steam fog forms over warm water in cold air. Radiation, advection and upslope fog all form by cooling a single air mass rather than by mixing two, so the mechanism is quite different even though the result looks similar. Working one numerical case through both cases side by side fixes the distinction better than any rule of thumb.

Answer: D

Cold air flowing over much warmer water is rapidly moistened and mixed, and because the saturation curve is convex the mixture becomes supersaturated and fog forms. Arctic sea smoke is the extreme case. Advection fog forms by the opposite arrangement, warm air over a cold surface, which is a useful contrast to draw explicitly.

Answer: A

Advection fog forms where air is cooled from below to its dew point, most commonly where warm maritime air crosses a cold ocean current or a snow covered surface. The Grand Banks and the California coast are classic locations. Unlike radiation fog it can persist in moderate winds and can form at any time of day.

Answer: B

The cooling is supplied continuously by the surface as fresh air is advected over it, so moderate wind sustains rather than destroys the fog. Radiation fog by contrast requires calm conditions because wind mixes it away. The distinction explains why sea fog can persist for days while land fog often clears within hours.

Answer: C

The ground must cool efficiently, which requires clear skies, and the air must be nearly calm so that only a shallow layer is cooled, yet moist enough to reach saturation. Very light wind of one or two metres per second actually helps by mixing the cooling through a sufficient depth. Cloud cover prevents the radiative cooling entirely.