Do wind turbines affect the weather?

Will - As we ramp up our usage of renewables and a bit to combat climate change, our construction of wind farms grows ever bigger. Wind turbines can be over 200 feet tall with blades not far behind in size as well. Their presence not only slows wind passing through an area, but also creates kinetic movement of air as the blades rotate. So could this affect weather given that much of the weather is just air moving around in funny ways to find out? I put in a call to the founder of the British Weather Services, and author of 'Weather or Not', Jim Dale.

Jim - There'll always be, on a local basis, some kind of effect a bit like your back garden has different effects for the wind blowing in a certain direction, the sun, et cetera. So this is very similar and I think it's such that, yes, there will be some breath of winds blowing, it will create some local disturbances here or there, but I wouldn't at this moment think that it would take it much further than that. I think if you're sitting under these things, you might actually start to feel something that's going on around you, say on a calm day. But I think in the general play of things, in terms of it affecting the actual weather, I would suggest to you that if it does then it's probably quite, quite minimal, but yet to be fully determined, I think is probably the best sentence I can come up with.

Will - Doing a bit of napkin maths, it seems that the average offshore wind farm is about less than half a square kilometre in size. So I don't know how much of a wide reaching impact that could have.

Jim - Yeah, probably a bit more than a butterfly's wings, if you get my drift. There will be some there just like a propeller of a helicopter. You've got to say that if you are in and around these things then there will be disturbances, but not to the point where you're necessarily, you know, being bowled over by these things and it's adding necessarily to the wind velocity. On a stormy day, for example, I often see wind vanes being blown over broken. I say often, occasionally, when the winds get high enough or when, for example, lightning strikes, that type of thing. So it's not a complete and utter positive and you know, in terms of where they stand and what might happen to them or around them. But at the same time, as I say the positives far, far outweigh the negatives as far as we know at this moment in time. So I think we press on regardless.

Will - Yeah, I think you echo the sentiment of someone on our forum called Bored Chemist who says any direct effect will be tiny. The reduction in CO2 might be significant and I think that trade off to me personally is worth it.

Jim - Yeah, in life generally there's always a trade off between the good, the bad and the ugly. And as long as the good outweighs the bad and definitely the ugly, then you're going in the right direction. And that's what science is about. Good science, positive science is about moving in that direction for the benefits of all. And that's what I think we've got in this case so long may it live.