Meteorology and Oceanography
Meteorology and Oceanography tests weather interpretation, forecast use, wave and current prediction, and heavy-weather routing. The master must translate synoptic information into a safe passage plan and recognise when forecasts conflict with observed conditions.
Core rules
- On a synoptic chart, closer isobars mean stronger geostrophic wind; in the Northern Hemisphere, Buys Ballot puts low pressure on the left when your back is to the wind.
- Fronts bring wind shifts, poor visibility and precipitation; fog forms near dew point; sea breeze is diurnal.
- Significant wave height is the mean of the highest third of waves; swell can outrun its generating wind.
- Tropical revolving storms require early avoidance; in the Northern Hemisphere the dangerous semicircle is the right-hand side relative to track.
Worked example
In the Northern Hemisphere the wind is from northwest. Stand with your back to the wind, facing southeast. Low pressure is on your left, which is northeast. Therefore the low centre bears northeast of the vessel. The reasoning is Buys Ballot's law, not a direct bearing to the storm centre; it identifies the side of the isobar pattern where pressure falls.
Traps
Treating wind direction as 'to' rather than 'from'; reading isobars as wind arrows; confusing the dangerous semicircle in each hemisphere; and using swell height as total sea state. Ice accretion and storm surge are also common omissions.