View of a windmill farm in La Ventosa, Juchitan community, Oaxaca State, Mexico. (PATRICIA CASTELLANOS/AFP/Getty Images)

This weeks question comes from David Burtt in North Gower, Ottawa. David asks:

I am curious to know the effects on climate that may be caused by the very large wind turbine farms. The turbines are obviously absorbing energy from the wind, so is there an effect "downstream", from the farm?

We went to David Johnson, a [WISE Member and] Professor of Mechanical Engineering at the University of Waterloo.

He said to answer this question it's important to note that there have only been a few experimental studies done to observe a link between wind turbines and changes in measure of climate such as temperature.

Wind turbines absorb the motion of wind as kinetic energy to generate power. Downwind the speed of the wind is reduced and turbulent — this trailing wind is called a wake.

Johnson says studies have found very small increases in temperature (about 0.1-0.5 deg C) near the ground, inthe wake of the turbine, at night.

Normally, at night the air high above ground is warmer, while the air closer to the ground is cooler. The wake from the turbines mixes the warmer air from above and draws it closer to the ground increasing the temperature near ground slightly. However, these studies have concluded that the impact of the wake-reduced wind disappears shortly after the wind farm.