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This question already has an answer here:

Update:

Granted the question has been asked in different form; but the answer still escapes me.

At one place I read that locations in question have low sea-surface temperature. At another place I read that due to land positions (or lack thereof) causes wind to not gather speed.

The answer mentioned in duplicate-suggestion-question are related to vertical wind shear.

Plus, my question is which of the following four options would you pick and why and why not others.

This was an MCQ in a recent exam, with only one option being correct:

  1. Sea surface temperature are low.
  2. Inter-tropical Convergence Zone seldom occurs.
  3. Coriolis force is too weak.
  4. Absence of land in those regions.

I have doubts as:

Sea surface temp are a tad bit lower in those regions. Also, the ITCZ seldom crosses southwards. (Am I wrong?)

Coriolis force is good in 5 degrees to 30-40 degrees. (I think)

Since, there can be only one option true, which one is true?

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marked as duplicate by gansub, arkaia, Fred, Gimelist, Jan Doggen Sep 4 '15 at 17:33

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • $\begingroup$ aoml.noaa.gov/hrd/tcfaq/G6.html. The correct answer is (2). For details check that link out. It is ultimately related to wind shear. $\endgroup$ – gansub Sep 4 '15 at 10:52
  • $\begingroup$ NOT a good question, and I entirely disagree with gansub's answer. All we can do is definitely rule out 1) and 3). This and this clearly show SSTs are fine. Coriolis increases with latitude equally in both hemispheres. $\endgroup$ – JeopardyTempest Jun 9 '17 at 9:57
  • $\begingroup$ However, the ITCZ does not generate many of the Earth's TCs... and in fact this graphic suggests it's located similarly in other SHEM basins. It's responsible for a percentage of storms in other basins... but so are land-caused features like African waves and diurnal convective cycles. That makes 4) just as fair to me (though no less right). (of course frontal [and monsoon] troughs are a third unmentioned option common for TC generation). Point being, none of those answers look reasonable to me. $\endgroup$ – JeopardyTempest Jun 9 '17 at 10:04
  • $\begingroup$ It's indeed shear. As to why so much shear, that's really the fundamental question, and don't know off the top of my head, but interested for a more in-depth answer. If we say there was a lot of shear in the Atlantic basin causing decreased TCs, people want to know why. It's reasonable to say we don't know... but people don't like that as an explanation, and seasonal forecasts would disappear in smoke (as perhaps they should given their rather low skill and usefulness!) if such a huge factor had no foundational explanation. The answer may indeed be "it just works out that way" $\endgroup$ – JeopardyTempest Jun 9 '17 at 10:06
  • $\begingroup$ @JeopardyTempest - do you still entirely disagree with my answer ? :) $\endgroup$ – gansub Nov 17 '17 at 9:57