The fans can be turned on when temperatures drop to the freezing point. They break up a layer of colder air close to the ground that can harm budding flowers.
Something similar happens at wind farms.
Researchers used satellite data from 2003 to 2011 to examine surface temperatures across as wide swath of west Texas, which has built four of the world's largest wind farms. The data showed a direct correlation between night-time temperatures increases of 0.72 degrees C (1.3 degrees F) and the placement of the farms.As in the orchards, the cool air next to the ground is mixed by the blades with warmer air above.
Will this "put a damper on efforts to expand wind energy as a green energy solution"?
At first, I thought no, because it is just a local phenomenon. But in the overheated (sorry) debates on energy policy, expect to see this finding dragged in.