Hurricanes seem to run out of steam when they make landfall.

If our planet were entirely covered by ocean, would hurricanes continue indefinitely? Would they keep gathering energy and increasing in intensity until...?


No. As it is, many hurricanes never make landfall. In an oceanic world I could see three fates happening:

  1. Hurricanes that dissipate due to dynamical features or climatological features.

    By dynamical features, I mean things like two hurricanes that shear each other out or produce an environment that can't be sustained. An example of the latter is upwelling, which generates cooler water that saps the energy from the hurricane. A climatological feature that might prevent a hurricane from developing indefinitely might be the Azores high. As it is, there are places that hurricanes don't seem to go.

    enter image description here

  2. Hurricanes that undergo extratropical transition.

    Notice in the figure above, the hurricanes just disappear near the poles? As they come closer to the poles, the temperature difference becomes larger. Eventually they no longer look like tropical cyclones/hurricanes (little to no temperature difference), but rather look like an extratropical cyclone (see this link for some differences). This process is called Extratropical transition.

  3. Chavas and Reed (2019)

    While looking up papers for this question, I stumbled upon this paper. It implies that we would get longer lived hurricanes spreading the entire planet. I'd be a little skeptical of this result though, since it ignores the fact that the earth is heated unevenly, which drives most of the climate.

On a side note, such simulations do exist. These are called Aquaplanet simulations. Some studies I found include:

And for kicks and giggles, if you want to consider what the worst-case scenario for a hurricane could be, such a thing has been named a "Hypercane" (see here, too).

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    $\begingroup$ What's the deal with that one solitary hurricane on the eastern coast of South America? $\endgroup$ – probably_someone Aug 31 '20 at 2:07
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    $\begingroup$ @probably_someone That would be Hurricane Catarina (en.wikipedia.org/wiki/Hurricane_Catarina). $\endgroup$ – BarocliniCplusplus Aug 31 '20 at 2:54
  • $\begingroup$ When you write uneven heating drives most of the climate, do you rather mean it drives most of the weather? $\endgroup$ – gerrit Aug 31 '20 at 9:30
  • $\begingroup$ @gerrit Well, it arguably drives both weather and climate. Without uneven heating, there would be no global circulation that resembles our own. This changes the pattern of where cyclogenesis may occur, as well as creates more of a boundary for where cyclones may travel. $\endgroup$ – BarocliniCplusplus Aug 31 '20 at 9:50
  • $\begingroup$ So would it be an accurate analogy to say that a hurricane making landfall is like a rolling ball stopping on a raised ledge? Many balls stopped without the need of that ledge, but the balls that made it to the ledge are statistically likely to be stopped by that increased threshold it now needs to cross? $\endgroup$ – Flater Sep 2 '20 at 10:21

What is possible in a low-friction world is illustrated by the Great Red Spot on Jupiter, an anticyclonic storm that has has been continuously observed that fluid planet's surface at least since 1878 (142 years). Though it has shrunk a bit from its biggest size, it's still big enough to cover the Earth. The Great Red Spot may have had a longer history, possibly going back another two centuries:

The Great Red Spot may have existed since before 1665, but the present spot was first seen only after 1830, and well-studied only after a prominent apparition in 1879. The storm that was seen in the 17th century may have been different than the storm that exists today.[1]

Our own planet is too small for that, but a storm covering a similar fraction of Earth's surface would be as large as the contiguous 48 United States.

Cited reference:

1. Karl Hille (2015-08-04). "Jupiter's Great Red Spot: A Swirling Mystery". NASA. Retrieved 2017-11-18. Link

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    $\begingroup$ 1878? Huh, I thought it was the late 17th century by Cassini. $\endgroup$ – BMF Aug 30 '20 at 16:35
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    $\begingroup$ That is continuous observation. While the GRS was known and observed intermittently before 1878, we are not sure Cassini actually saw the same storm. $\endgroup$ – Oscar Lanzi Aug 30 '20 at 16:43
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    $\begingroup$ The Great Red Spot is sitting on the boundary between two of Jupiter's circulation bands. In contrast, cyclones on Earth almost always form inside circulation bands and then travel across them -- I'm not aware of any cyclone getting "caught" in a boundary. $\endgroup$ – Mark Aug 31 '20 at 20:22
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    $\begingroup$ Another fundamental difference is Jovian weather is driven by heat from its core rather than the Sun. $\endgroup$ – cms Sep 2 '20 at 11:45

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