Eli5: Why do hurricanes get stronger in warm water? And are the sea based or sky based? (Cloud)
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The warmth of water is the power that fuels hurricanes.
Start with warm water and cool air. The water transfers heat to the adjacent air; the now-relatively-warm air rises; and other cool air from nearby rushes in to take its place. So now the water is cooler, some air is warmer, and some air is *moving*.
So it’s not just that warm water makes the hurricane stronger: it’s what created the hurricane in the first place. The moment the water is no longer significantly warmer than the inrushing air, the hurricane will act like an electric fan that’s been unplugged, gradually spinning to a stop.
So, one of my very first lessons in thermodynamics when taking Physical Chemistry (a class all about thermodynamics) was being taught something called the Carnot engine. A Carnot engine is a mechanism through which heat gradients can do work/generate forces. Now, I don’t understand it well enough to to teach it to you, but the example of a Carnot engine my professor told us about are hurricanes. The warm water feeds energy into the colder, low pressure air above it. So, it’s both a sea based and sky based phenomenon
A hurricane is a heat engine, driven by the temperature and enthalpy gradient between the warm, moist air at the ocean surface and the cold, dry air at the top of the troposphere. The warmer the ocean is, the more temperature gradient and enthalpy (in the form of water vapour in the air) there is to feed that heat engine, and so the stronger it can be.
That is also part of why hurricanes dissipate once they reach land. Going over land instead of ocean means they get cut off from the supply of warm, moist air that feeds them, in addition to the increased friction they experience over land vs over ocean causing faster energy loss out of the storm system.
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