Bullimore was sailing through the notorious Southern Ocean when his yacht capsized. This region has been dubbed the 'Roaring Forties', 'Furious Fifties' and 'Screaming Sixties' by sailors – a reference to the wild and unpredictable weather found between 40 and 60 degrees latitude.
Gale force winds and huge waves are caused by weather systems and currents that circle Antarctica unimpeded by land masses. The Antarctic ice sheet produces very cold, dense air that drains towards the coast. These katabatic winds move slowly at first but accelerate under the influence of gravity as they travel down from high altitudes, reaching speeds of up to 40kph.
As the winds move north over the Southern Ocean, they interact with warmer air from the north. This creates low pressure systems or polar cyclones that ride the Southern Ocean. The strongest of these westerly winds produce hurricane forces. Wind speeds of 120kph are common but they can reach more than 250kph.
Making seafaring conditions even more treacherous is the Antarctic Circumpolar Current which flows against these winds in an easterly direction. This is the largest ocean current in the world, transporting five times more water than the Gulf Stream in the Northern Hemisphere.
This massive wall of water acts like a cold insulator, blocking warmer tropical waters from the north and maintaining Antarctica's permanent ice sheet. Antarctic coastal temperatures can drop as low as minus 50°C.
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