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Not sure if my intuition here is right.

All else being equal, would a massive ocean yield larger and more severe storms? If, say, we removed the Americas, would the new Atlantic-Pacific Ocean be much more difficult to cross, and would Asia, Africa, and Europe be bombarded with more severe storms?

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Quick Bio. I am a master mariner and cite the Mariner's Handbook and This BOM article.

Quick answer. It depends on the latitude of the east coast of the continent impacted.

It is important to distinguish between high latitude lows and tropical revolving storms (TRS, Hurricanes, Cyclones, Typhoons).

TRS generate at 5-15 lat and (in the N hemisphere) move NW before recurving to the NE. This is varied by (because they are heat engines) their tendency to follow warmer water. One of the reasons the US east coast hurricane is so damaging, although on average smaller, is that their natural direction of recurvature and the Gulf Stream carries them up along the densely populated coast into much higher Lats than seen on the Asian or Australian coasts because there is warm water further north. In addition the Gulf of Mexico is a large shallow warm sea and this spins them up.

Pacific TRS tend to be larger and more damaging because of fetch (distance available to develop). Essentially because the Pacific is wider than the Atlantic TRS' have time to become fully developed before they make landfall. Extra width (No Americas) would not make the situation worse for Asia because TRS that develop E of about 180° (about halfway across the Pacific) recurve to the NE before they reach the coast.

No Africa would make a difference to the Americas because an Atlantic TRS would then have time to fully develop before hitting the warm Gulf water and spinning up further.

This amplification can happen in the Pacific when the water in the S China Sea or Coral Sea is very warm (Cyclone Joy). This combination can lead to very large and devastating systems (which the sensible mariner avoids).

In high latitudes the best model to think of is the Southern Ocean. This is essentially a World Circling ocean with only one land barrier (Cape Horn / Antarctic Peninsula). Westerlies prevail and High Latitude depressions spin off the Antarctic and slide NE along the Antarctic front. The winds and seas become fully developed and the conditions become as extreme as physics permits. Shipping transits the Southern Ocean routinely. Unsurprisingly W to E routes are preferred. If it is necessary to travel E to W

  1. One plans for a lower lat transit if possible / economically viable
  2. In some cases it is most effective to go 'the long way round' with the weather rather than the shortest distance against the weather. The Tea clippers did this, going under Cape Horn rather than beating to weather under the Cape of Good Hope.

TRS and high lat lows can combine. Cyclone Steve in 2000 hit the Aust E coast off Cairns, travelled across the N coast, down the W coast, combined with a polar low, travelled along the S coast and blew out in the Tasman Sea. In this case the system circled the continent.

In the Atlantic the Gulf Stream can lead hurricanes toward Europe. A tropical and polar low can combine in the N Atlantic but the system is no longer a TRS, essentially a reinforced high latitude depression. In this case the system circles the quasi-stationary mid-Atlantic High.

Note that both these circumstances can only arise with specific combinations of water temp and geography thay will only occasionally arise.

Notice that no Americas, no Gulf Stream and no hurricanes in the North Eastern Atlantic. Notice here that no (few) TRS in the NE Pacific. They spin up in the E, travel NW to the central Pacific, recurve to the NE, hit the cold California current and die (vast oversimplification here). In the NW Pacific the northern travel of TRS is suppressed by cold currents out of the Bearing Straight.

In summary the precise geography and oceanography is important. Our understanding of how these systems form and develop is still imperfect.

There is also a countervailing effect. There is a band of light winds on the equator side of the oceanic quasi-stationary high (the Horse Latitudes). Removing a continent will only extend this, in a way providing a calm(ish) E-W sea lane.

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  • $\begingroup$ And more specifically in relation to Europe to remove the Americas would completely change the climate. It would most closely resemble the Pacific NW. The British Isles would have a climate resembling Vancouver Island. $\endgroup$ – pHred Mar 10 '17 at 11:19
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Short answer: yes.

Proof? Examples will have to do (I'm no meteorologist). Typhoons of the Pacific ocean (62.46 million mi²) are typically more powerful than hurricanes in the Atlantic (41.1 million mi²). BUT! There are some that theorize this is because of the spin of the storm. You can check Weather Underground for historical data, but I can't find a comparative source.

The take away from this, is that land weakens the storm. Open waters strengthen it. This has to do with water surface temperatures, with the 'dangerous' or active times being statistically around when the temperature of the water exceeds 25 degrees Centigrade. More importantly, the higher the gusts, the slower the system, giving it more time to build up before landfall. (I'm from the Caribbean, this is a yearly occurrence here).

Keep in mind that the storms of the North Sea (for example) start off down in the Atlantic, follows the air currents up to Europe, and is considerably weakened up there. The water is too cold to sustain the weather system when compared to warmer waters.

There's also the theory behind high and low pressure systems (which can form over land, though never create storms as power as over open waters, because of moisture differences). Check here for more information.

Am I certain? The Great Red Spot on Jupiter agrees with me. Don't like it, then you should take it up with the Jovians ;)

And I blame kingledion for egging on my inner nerd. Seriously, she's a slave driver! (my inner nerd, not you kingledion)

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  • $\begingroup$ I'm pretty sure you are right, but this could stand a little more evidence. Also, examples are not proof :) $\endgroup$ – kingledion Mar 10 '17 at 0:07
  • $\begingroup$ @kingledion true, but the source does a lot of explaining ^_^ $\endgroup$ – Fayth85 Mar 10 '17 at 0:08
  • $\begingroup$ @kingledion thanks for egging my inner nerd on. She's not happy with you. $\endgroup$ – Fayth85 Mar 10 '17 at 0:19
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    $\begingroup$ I'm soooooo not doing pictures or a powerpoint presentation... $\endgroup$ – Fayth85 Mar 10 '17 at 0:29
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    $\begingroup$ -_- <-- that's me glaring at you @ShadoCat $\endgroup$ – Fayth85 Mar 10 '17 at 0:58
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It depends. for instance, The Pacific ocean is larger than the Gulf of Mexico and The Atlantic Ocean combined, but still the Atlantic and GOM still produce much more hurricanes and storms. It also depends on pressure, wind speed, and temperature differences.

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  • $\begingroup$ I live in Georgia and I had a 1st hand experience with Hurricane Matthew and Hermine. $\endgroup$ – SavageCabbage Mar 10 '17 at 0:27

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