[saspinski (OP)]

I have read about the warm sea as the driving force for the hurricanes, and the Coriolis acceleration as the reason for its rotation. But I could not find a logical connection for the event as a whole. I will try below an explanation step by step, and would like to know if it makes sense, or where I can find a better one:

1) In regions of shallow waters and near the tropic parallels (Gulf of Mexico for example), the sun light is maximum in the summer. Because the sea is shallow, it warms more than the ocean nearby.

2) A lot of water evaporates from that warmed sea, and the added molecules force a displacement of the existing ones in all directions.

3) As the air pressure is lower above than sideways, most of the expansion is upwards.

4) The equilibrium outcome is a huge volume of warm air above the sea, if there are not winds to dissipate and disturb that state.

5) When the summer finishes, the sun light (the actual driving force for the expansion) in the same region weakens.

6) All that volume of air loses some temperature and its pressure drops as a consequence.

7) Air from outside moves to that region, due to the pressure difference.

Due to the Coriolis acceleration the radial winds deflect sideways

9) An hurricane is formed.

[alancalverd]

Generally a fair picture but it's a bit more complicated. Let's first consider a simple model of the northern hemisphere.

Dense, cold air in the polar regions will have a high surface pressure, so it flows outwards towards the equator, displacing lower density warm air upwards, with a counterflow at high level. Polar air has very little circumferential speed but the planet surface is moving eastwards at around 1000 mph at the equator, so as a cold air mass moves south it produces an easterly wind - the Coriolis effect. The movement is not evenly spread - "tongues" of cold air penetrate the tropical zone, forcing similar tongues of warm air to move northwards as well as upwards. Thus we get discrete spiralling flows in the tropical region.

As warm moist air rises, it cools. At the condensation level (cloud base) the latent heat of condensation is released as kinetic energy, increasing the vertical speed of the draught and thus pulling in more air from below - the spiral flow intensifies.

Now the same thing is happening south of the equator, again producing an easterly surface wind in what is now called the intertropical convergence zone, thus further intensifying the spiral flow.

The spiral flow regions drift westward and if the temperature difference between the polar and tropical air is sufficient, the rate of rotation (i.e. the surface wind) increases as the clouds form. Hence we have a hurricane cell.

Just to make it more interesting, there are actually three vertical convection  cells in each hemisphere: polar, Ferrel and Hadley. The Ferrel cell  is centered around the temperate zone , with the low level air moving from the tropics towards the poles and producing a prevailing westerly  coriolois wind. This is the cell that generates the Atlantic lows which dominate UK weather - same broad principle but much less energetic.

Matters are further complicated by the presence of land masses which produce additional strong local convection as the spiral systems make landfall. As most of the land in in the northern hemisphere, the development of hurricanes is quite different, being more frequent and intense north of the equator.