The December 18 & 25, 2004 issue of Science News (pg. 411) reports on an interesting computer simulation. There, below a photo of a row of wind generators, you can read, "Computer simulations suggest that large groups of power-generating windmills... increase wind speed, temperature, and evaporation at ground level, ... influencing a region's climate." Delving into the research, I learned the following.

The Journal of Geophysical Research reports the study was conducted by scientists from Princeton and Duke Universities and has been backed up by observations from real wind farms. Somnath Baidya Roy of Princeton and his colleagues say that massive wind farms significantly increase local surface drying and soil heating, which in turn would impact agricultural or range use on or near the wind farm.

While the turbines in the study are large – 100 meters high with blades 100 meters in diameter – they are much smaller than some in use. And while the study’s wind farm is large, it is much smaller than would be needed to supply the amount of energy being proposed by the wind energy industry.

The Princeton-Duke authors are concerned that the rapid whirling of the blades will strongly churn the local air and generate significant local turbulence. That turbulence changes the distribution of moisture and heat in a volume of air much greater than the shape of the turbine. In fact, the turbulence made by the turbans extends to heights of 1 kilometer above the ground.

According to the model results, turbulence from a very large wind farm would warm the air near the ground by 2°C (about 4°F) for several hours during a summer day and about 0.7°C average over the entire day and night. It would also promote significant evaporation of soil moisture.

How such a change might affect local wildlife is unknown.

Meanwhile, Gustave Corten of the Energy Research Centre in Petten in the Netherlands has conducted experiments with a model wind farm in a wind tunnel and reports that large wind farms “will affect the microclimate.”

British scientist Professor James Lovelock, originator of the Gaia concept, says, "... I do wonder whether a million giant wind turbines [will] adversely affect the vorticity (circulation) of the atmosphere."