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Hurricanes: Necessary Conditions for Formation |
| (1) Surface water temperature ³ 80°F (26.5 °C) |
| (2) Deep, warm, humid, surface layer of air |
| (3) Light surface winds |
| (4) Surface convergence (often acts as a "trigger") |
| (5) Systemic rotation (adequate Coriolis force requires |φ| > 5°) |
| (6) Absence of strong "trade wind inversion" (associated with subsidence in subtropical highs) |
| (7) Light upper-level winds |
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(8) Upper-level divergence |
| Possible Hurricane Formation Sites |
| (1) Eastern side of an easterly wave |
| (2) Wave in the ITCZ |
| (3) Front which has moved into tropics from middle latitudes |