Can Wind Farms Change the Weather?

Researchers are investigating the potential for large wind farms in one region to alter weather patterns in another region downwind. Specifically, the turning of the wind mill propellers creates considerable turbulence, which mixes air up and down. The resulting bumpiness of the air could significantly influence winds at low levels of the atmosphere.
Kirk-Davidoff and his UMD colleague, Daniel Barrie, used a global general circulation model of the atmosphere (similar to the models used to predict climate change) to calculate the effects of blanketing the Midwest with a grid of interconnected wind farms with thousands of wind turbines. On average, the study found that wind speeds were lowered by 5.5-6.7 miles per hour immediately downwind. More significantly, the wind turbines caused large-scale disruptions of air currents, which rippled out like waves that appeared to trigger substantial changes in the development and track of storms over the North Atlantic.

The magnitude and degree of the impact of such wind farms would presumably be less than in the model simulation. But still the consequences, while unintended, could be significant, especially in situations involving storms such as major winter cyclones forming along a strong frontal zone. Ensemble forecasting has shown that even apparently innocuous changes in the low-level wind field can result in large uncertainties in the timing, strength and motion of major storms over a period of just a few days.

Wind farms may also result in important changes in local climatology, potentially impacting, for example, agricultural interests located within and immediately around areas encompassed by wind farms. The turbulence induced by the propellers of wind turbines mixes air along with the heat and moisture it contains — the effects can spread for miles around. This is especially true at night when the disturbed airflow is not masked by the natural turbulence caused by solar heating.

Based on computer modeling, researchers at Duke and Princeton universities found that wind mill-generated turbulence raised pre-dawn surface temperatures by about four degrees and resulted in drier soil conditions.

Washington Post