Meteorology and Oceanography
What the meteorology paper tests
You must read a synoptic chart, apply Buys Ballot, judge sea state and visibility, and recognise the local weather that shapes Norwegian waters: polar lows, coastal icing, advection fog and the Skagerrak wind funnel.
Core rules
- Buys Ballot (northern hemisphere): stand with your back to the wind and low pressure is on your left, about 90 to 120 degrees off the wind direction.
- Geostrophic wind blows parallel to the isobars; the closer the spacing, the stronger the wind. Friction over the sea turns the wind about 10 to 20 degrees towards low pressure.
- Frontal weather: warm front brings continuous rain and falling pressure, cold front brings squally showers, a sharp veer of wind and rising pressure.
- Fog: radiation fog forms over land on clear calm nights; advection fog forms when warm moist air moves over cold water, common over the North Sea and Norwegian Current boundaries.
- Sea state depends on wind speed, fetch and duration; swell persists after the wind has gone. Waves steepen in shallow water and against a current.
- Polar lows form over open sea behind a cold front, are small and fast-moving, and can produce storm-force winds with little warning.
Worked example
A tropical revolving storm is reported bearing 090°T, 200 nm away, in the northern hemisphere, with the wind at your ship from 180°T. Wind backing or steady with falling pressure and the storm to the east means you are in the navigable semicircle: put the wind on the starboard quarter and steer to increase distance, making maximum speed. If the wind had been veering with pressure falling, you would be in the dangerous semicircle and should put the wind on the starboard bow.
Traps that cost marks
- Applying Buys Ballot the southern-hemisphere way in northern waters.
- Treating a rising barometer after a cold front as worsening weather.
- Confusing fetch with duration; both limit wave height.
- Calling any fog over water advection fog without checking the temperature gradient.