Meteorology · Global Circulation — Westerlies
The prevailing westerlies of the mid-latitudes (roughly 40°–60°), including the Southern Ocean's 'roaring forties,' are significant to passage planning because they:
- ABring a steady west-to-east flow with frequent migrating lows and gales, favoring eastbound routes✓ Correct
- BAre light and variable like the doldrums
- CBlow consistently from the east toward the equator
- DProduce permanent high pressure and calm seas
Explanation
Between the subtropical highs and the polar fronts, the westerlies flow generally west to east and carry a procession of mid-latitude depressions with frequent gales. In the Southern Ocean, with little land to slow them, they become the notoriously strong roaring forties and furious fifties.
Authority: Bowditch (Pub. No. 9), global wind systems; WMO; NGA Pilot Charts
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