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What are the latitudes and tracks in the North Atlantic Ocean where tropical revolving storms move as they develop and mature?
  • A
    5°N to 20°N moving from east to west, turning to NE direction only.
  • B
    20°N to 25°N moving from west to east, turning into south-east direction.
  • C
    10°N to 15°N moving from east to west, generally turning to Northerly directions.
  • D
    10°N to 15°N moving from west to east, turning into southerly direction.

Refer to figure.

TROPICAL REVOLVING STORMS (TRS). Are thermal depressions that develop over warm tropical oceans (wind speeds in excess of 33 kts). When they sustain wind speeds greater than 63 kts, they are designated tropical cyclones. TRS generate their power and energy from the release of large amounts of latent heat from moisture they have gained over the warm seas.

Tropical revolving storms only form in certain conditions:

  • Must be within 5 and 25 latitude (Below 5º, Coriolis force is too small, above 25º latitude the sea is usually too cold)
  • Ocean temperatures must be greater than 26.5ºC. The higher the ocean temperature the greater the pressure drop within the core => This is the reason why we do not usually have TRS forming in the southern Atlantic because the sea surface temperatures are too low.
  • Sufficiently unstable atmosphere at low level (so convective clouds penetrate the Trade wind inversion).

Direction of Movement

After a Tropical Revolving Storm forms, they usually travel Westwards (from east to west), in the Northern Hemisphere. In the mature stage, they begin to turn Northwards (in the Northern Hemisphere). The storm, then, may re-curve at around 20°N or S => where it might then track North-Eastwards (It must be noted though that recurvature may not take place).

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