Wind Weight

At 2000m height the air density is 20% less than at sea level. So you would definitely feel less force in the sails at the same wind speed compared to sea level.

The opposite applies to a lesser extent with cold air. If are hardy enough to sail at 3C, the air is 10% denser than on a hot summer day of 30C. So the same wind speed will feel "heavier" in winter. Lots of people claim to observe this but I'm not really certain a 10% difference in force would be that noticeable. The force exerted by the breeze is proportional to the square of the windspeed, so a 5% change in windspeed causes a 10% change in force (more or less). 5% change in windspeed is the difference between 20 and 21 knots, and how many of us would really be able to tell the difference between a steady 20 and 21 knots?

In the 4th November issue of YnY, Andy Rice was talking about wind weights and americas cup. A reader has sent an email in this month explaining that it is not possible, I wondered what other people thought.

Myself I think that there is such a thing as wind weight. Because last year the 29er Worlds were in Silvaplana which is 1850m above sea level were the air is less dense and i remember the first day reading 25knots average my anemometer when only felt about 18knots. Get back to the UK doing some winter training at weymouth (-13 degrees windchill) with anemometer reading 18knots when it felt like 25knots. Or am i just stupid and the wind is always the same?

Also the reason why the anemometer will read the same wind speed for 2 different air densitys is because the air/paritcles in the air is going that speed but the particles are more spread out in the less dense air so there are less particles hitting your sail even though there hitting it at the same speed therefore it feels like less wind?????

what do other people think?

I dont really know but find it quite interesting