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British Olympic Sailing Team Meteorologist Fiona Campbell gives us an introduction to the Olympics and the weather associated with the games.

The Winds in Athens

I would be a rich women if I had a pound for every time someone has said to me, before a sailing event, "it always does this" and then during the event, corrects themselves by saying "it never usually does this!".

Athens has the potential to be one of those classic events as there are two main and often fighting wind systems influencing Olympic sailing conditions.

The stronger of these winds is the Meltemi wind. It is a north to north easterly wind which due to the local terrain funnels down from the mountains and out of the city providing gusty offshore conditions on the race courses. It is created by a pressure gradient set up between high pressure to the north east of Greece, and a thermal low which forms over Turkey.

The Meltemi produces hot and dry conditions with speeds between 8 and 28 knots, lasting anything between one day and two weeks, though normally about three or four days.

The heating and frictional effects of the land cause this wind to be incredibly shifty and changeable which can provide problems for the sailors. High gusts of up to 30 knots can be followed almost immediately by lulls as low as 10 knots.

Sailors can find it difficult to predict any kind of pattern in the wind shifts, if they can get it right during the race the results will speak for themselves. These types of conditions could make it easier for those slightly lower down the rankings to do extremely well and possibly create some 'surprise' results.

This offshore wind has an opponent in the form of an onshore sea breeze. It is driven by the warming and rising of the air over land and sinking of the cooler air over the sea, during the course of a day and reaching its maximum speed by mid afternoon. However in the height of the Athens oppressive heat this is not always a very strong or stable breeze.

Maximum speeds can reach 10 - 14 knots but more often than not it remains below 10 knots and often even lighter for long periods of time. Race start time is scheduled to be 1300 but winds of 6 knots or more, required for a sensible race, do not always fill in until after 1430 and may last only a few hours.

Meltemi synoptic circulation

The difficult days to predict are the fighting days. These are when the Meltemi and sea breezes are both in force and can lead to different conditions on the four race courses, or worse, different conditions on a single course.

Before the start of the Olympics in 2002 there was a 180 degree wind shift caused by the switching off of the sea breeze effect, due to the cooling effect of a thundercloud. This led to a light onshore breeze being replaced by 30 knot down draught from the storm cloud during racing causing tornados and 49ers to pitch pole all over the course.

This is an extreme example as such a dramatic wind shift would cause the race to be scrapped if it occurred during the games, but it shows the kind of variability this region can dish up.

So from a strong offshore to a light onshore with some thunderstorms to mix up the conditions in between, one thing I can forecast for Athens is that no one can say "It always does this in Athens!".

Other features in this series
Weather and the Olympics
Introduction to weather and sailing in the Olympics
Meteorological Support in Athens
Weather and Tactics

Back to Olympics 2004

Sailing and Weather
The Boat Race 2004
Being Weatherwise for sailing