Archive for December, 2010

The Wind Is Dying

Thursday, December 23rd, 2010

Wind speed has significantly decreased in the 29 years from 1979 to 2008. In extreme cases, the wind decrease was a significant 15%. More specifically, the wind decreased at 73% of measuring stations which were 10 meters above the surface (about mast height for many smaller sailboats). The measurements were mostly from Europe, but also from the United States, China and Russia.

This wind decrease is attributed to an increased average roughness of the earth’s surface. A large part of the roughness increase is attributed to additional vegetation (more trees). Reforestation, abandoned farms and increased carbon dioxide levels all lead to more tall trees. New tall buildings also contribute to surface roughness.

The significance of this for sailors is not clear, since sailors generally try to steer clear of tall trees and large buildings. The wind decrease may have no effect on wind energy, since a wind decrease at 50 to 100 meters (where wind turbines operate) has not been seen.

This is a summary of results reported by Robert Vautard and others at the Climate Science and Environment Laboratory in France and the European Centre for Medium-Range Forecasts in the UK. [Nature Geoscience 3, 756, 2010, various web articles and Physics Today, December 2010, page 25.]