Creedence on Why the South Needs more Wind Turbines
September 2, 2016
Wind farm development in the south has been slow. At one time, the sauntering southern breezes seemed too sluggish to harness for wind farm development. Research, meteorology and advanced wind turbine technology have finally enabled economic wind farm development in the south. Two southern cultural references, mixed with some new science, help explain why wind power is suddenly a smart strategy.
If you’re a Creedence Clearwater Revival (CCR) fan, you know their bread and butter is all things southern. Bayous, catfish jumpin’, hurricanes a blowin’ and a bad moon rising…well, you get the gist. But think about this CCR song for a spell: Have you ever seen the rain?
Someone told me long ago
There’s a calm before the storm,
I know; it’s been comin’ for some time.
When it’s over, so they say,
It’ll rain a sunny day,
I know; shinin’ down like water.
I want to know, have you ever seen the rain?
I want to know, have you ever seen the rain
Comin’ down on a sunny day?
If you take the song literally, have you ever seen it rain when it’s sunny outside? If you’ve lived in the south much, chances are pretty good that you have. But it’s a less frequent phenomenon in other parts of the country. For the majority of Americans, they have no special term for when the rain falls and the sun is shining. Here in the south, that phenomenon is frequently referred to as the “devil beating his wife.” The origin may be from a French phrase, and as the French Acadians (Cajuns) settled in Louisiana, the southernism spread through the south following the rivers and bayous. As a more politically correct alternative, the phenomenon may also be called a “sun shower.”
So what does CCR and the devil beating his wife have to do with wind energy? It’s all about wind shear.
According to the Federal Aviation Administration, “wind shear is a change in wind speed and/or direction over a short distance. It can occur either horizontally or vertically and is most often associated with strong temperature inversions or density gradients. Wind shear can occur at high or low altitude.” The FAA’s interest in wind shear should be obvious: a quick change in wind speed or direction at low altitudes can prove dangerous or fatal for landing pilots. Passengers can experience wind shear as turbulence.
High wind shear can push clouds and rain around more than usual. When the sun, wind and rain are in proper alignment, a sunshower can occur. The sun is shining, but the rain is falling. Wind farm development companies have found that the south has higher wind shear than expected, and higher than many other parts of the country. By using slightly taller wind turbines, wind farm developers can reach much better wind speeds in the south, thanks to higher wind shear. So even for an observer on the ground, wind speeds may appear to be extremely low, when in fact the wind speeds are much better than expected.
When wind shear becomes extremely powerful, it can lead to spinning and twisting of the air column and that can trigger a tornado watch. If the south has a higher wind shear than other parts of the country, could the south be experiencing more tornado watches and warnings? Absolutely. In fact, new research from Dr. Ernest Agee, a professor in the Department of Earth, Atmospheric, and Planetary Sciences at Purdue University suggests that conditions favorable for tornadoes are shifting to the south. Research published earlier dubbed the southeast as “Dixie Alley” in reference to our higher levels of tornadic conditions or wind shear. Tornado watches are triggered when meteorologists see low altitude circulation, wind shear, and the south receives substantially more tornado watches than the rest of the country. Yes, tornadoes aren’t good for wind turbines, but wind turbines have been known to survive direct hits. But keep in mind tornado watches do not always materialize into full tornadoes (tornado warnings), just that the wind shear conditions are favorable for a tornado.
CCR’s Have you ever seen the rain? and the southernism “the devil beating his wife” or “sunshowers” describe a meteorological phenomenon attributed, in part, to wind shear. The south has a stronger wind shear than much of the rest of the country, and that’s why wind farm developers are so excited about taller wind turbines in the south.