Cyclones and Carnot cycle

[vero_81]

Thank you for your answer
Yes, I had read the paper. But there are some things I don't understand yet...

1) Is the first leg an isothermal expansion as in the Carnot cycle? Does air expand while moving inward?

2) Once arrived to the top, there is the condensation of water vapour. Is this phenomenon considered? If yes, in the second (adiabatic) or third (isothermal) leg?

3) I don't understand why the 4th leg is not important for the thermodynamic cycle...Isn't it necessary to close the cycle? To what it corresponds physically, in the cyclone?

byebye!

The first branch is along ocean surface, an isotherm with air moving inward; the second leg is an adiabatic expansion, with air first ascending and then flowing outward; the third is again an isotherm with air descending slowly; the fourth contributes little to the thermodinamic cycle.

You can find the original paper here (pdf, 950 kB), with a formal definition of the efficiency.

Hope it helps.

Yes I've read the paper.. The thing I do not understand

[Hydraulics]

Does air expand while moving inward?

Yes, as pressure drops.

Once arrived to the top, there is the condensation of water vapour. Is this phenomenon considered? If yes, in the second (adiabatic) or third (isothermal) leg?

Condensation and conversion from latent to sensible heat happens all along the second leg, not only at the top; and yes, it seems to me it is taken into account.

I don't understand why the 4th leg is not important for the thermodynamic cycle...Isn't it necessary to close the cycle? To what it corresponds physically, in the cyclone?

These are good questions, and as far as I can tell there are critical voices on this aspect. You may find interesting this paper and subsequent comments, above all the first from the authors, which deals exactly (and in detail) with these problems.

In my opinion, the analogy hurricane-carnot engine is a bit stretched, but I'm no expert in the specific field of hurricane physics.