Cyclonic energy explained
Peter Waterhouse, of Stewarts River (Australia), asked:
Does all this energy extracted from the ocean and expended during the high winds of a cyclone and its aftermath actually reduce the energy in the ocean and the atmosphere and, by extension, reduce the warming in the biosphere? Is it in effect an environmental safety valve, or just an outward visible symptom of an invisible climate aberration to be endlessly repeated as things get worse?
Tom Adams, a meteorologist with the MetService, responded:
The short answer is no.
Roughly speaking, the planet is nearly in equilibrium. Energy is received from the sun, and is radiated back into space, and these almost perfectly cancel out. If they don’t perfectly match then the planet will heat up, or cool down. Climate change is because of this slight mismatch, and at times in history (including now), the planet has warmed or cooled, but only on very long timescales.
Within the planet, energy is always moving around, from the ocean to the atmosphere and back again. The tropics receive more solar energy than the poles, so have to move this energy away from the equator to maintain equilibrium. Otherwise the tropics would keep heating up, and the poles would keep cooling down. Much of this energy is transferred in the form of latent heat. Water evaporates, storing latent energy, then releasing it when it condenses back into rain.
Tropical cyclones and fronts both transfer huge amounts of water vapour (and hence energy) from near the equator to nearer the poles. Energy is also transferred in the bulk movement of warmer air, but in fact much more energy is transferred in the bulk movement of water in the ocean through currents. Water has a much higher heat capacity than air, so is more effective at transferring energy.
Finally, energy is transferred through the kinetic energy of both the wind and the ocean, but the amount of kinetic energy is tiny compared to the amount of energy stored thermally. In fact, because of friction, high wind speeds will actually slightly warm the air, although the effect is negligible relative to the scheme of the entire global energy transfer. So to answer your question, energy is transferred from the ocean to the atmosphere through tropical cyclones, but only temporarily, and there is no net loss of planetary energy. So the energy is not expended, sorry; it stays on the planet and won’t change global warming at all.
Send questions to:
AskAScientist,
PO Box 31035, Christchurch 8444 Or email questions@askascientist.net