According to research in the USA wind farms can change the weather. Forests of wind turbines may interact with the local atmosphere and increase the air temperature. Surprisingly they even increase the wind speed as well.

And the research has been backed up by actual studies on real wind farms, said New Scientist magazine.

During the day the wind farms have little effect on the local climate because the energy from the sun mixes the air at lower layers. But at night, the wind turbines can have a significant effect, warming the night air by about 2 degrees centigrade and increasing the wind speed by 1.5 m/s, according to the research.

The overall effect during 24 hours averages out at increases of 0.7 degrees and 0.6 m/s.

The study, by Baidya Roy from Princeton University, and his colleagues has been backed up by wind data gathered from a real wind farm in California, where it was found that the turbines pulled down heat and momentum from above, particularly during the night-time hours.

Researches in the Netherlands are interested to see if improved designs would reduce the effect but nothing alters the fact that energy is being removed from the wind and Baidya Roy, whilst agreeing turbines might be made more efficient said, "People tend to think that renewable energy is for free, but it isn’t. There is a price to pay for all kinds of consumption, including renewable energy.”