Meteorology · Waves — Significant Wave Height
The 'significant wave height' reported in forecasts is defined as:
- AThe height of the single largest wave
- BThe average height of the highest one-third of the waves✓ Correct
- CThe average of all waves including ripples
- DThe wavelength of the longest swell
Explanation
Significant wave height (Hs) is the average of the highest one-third of the waves, corresponding roughly to what an experienced observer estimates by eye. Individual waves can be considerably higher — the occasional wave may reach nearly twice Hs — which mariners must keep in mind.
Authority: WMO; Bowditch (Pub. No. 9)
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