We receive a fair amount of reader correspondence here at PA Local — questions, answers, misguided defenses of Home Alone 2.
And that outreach has revealed a clear fascination — read: fixation — with lighting, so much so that we’ve decided to quickly explain two phenomena that keep finding their way into the ‘ole Gmail-bag. The first involves purple street lights, the second a purple/pink “aura” in the sky.
Let’s start with the former.
Street view
A few years ago, folks in cities nationwide started noticing that their public spaces had taken on a strange tint at night. The source? Their local lampposts.
In Schuylkill County, Tamaqua resident George Haldeman showed up at a borough council meeting as recently as this past September looking for answers. He wasn’t particularly alarmed but was definitely curious as to why some streets were suddenly lit up like a college dorm room.
It was a similar story in State College in October, and Willow Grove before that.
Conspiracy theories abounded, none of which I’m sharing here, but the truth was much tamer.
In an interesting piece for Insider, Adam Rogers writes that “The Great Purpling” of towns like Tamaqua across North America owed to defective batches of LED lights. It was that simple.
"There's a laminate on the fixture that gives it its [normal] white color," Jeff Brooks of Duke Power, which operates in the south and midwest, explained. "As that laminate began to degrade, it caused the color tint to change toward purple.” The most likely culprit was heat damage.
Without the laminate, an LED's true indigo color shines.
Officials in Tamaqua told George Haldeman that the manufacturer would pay for replacements. Officials in State College said they were working on swap outs too.
But there’s likely more purple in Pennsylvania’s future, especially with cities like Philadelphia in the process of converting tens of thousands of old sodium-vapor street lights to more cost effective, energy efficient, and powerful — sometimes to a fault — LEDs.
Glow-ups
If you’ve driven past the Brookville exit on I-80 in Jefferson County, you likely smelled the medical marijuana facility there before you saw it.
But the growhouses that dot the Pennsylvania map now, six years after the legalization of medical cannabis here, can be visible from a distance too — incredibly so.
Once again, LED lights are involved — only this time the coloring is intentional.
We’ve received a number of related messages, most featuring cellphone photos of intensely bright pink and purple clouds with bemused or irritated captions. There have also been lots of social media posts with near-identical queries, many suspecting that weather played a role.
Here’s what’s actually happening:
The greenhouses involved in the cultivation of cannabis often use powerful arrays of lights at various ends of the color spectrum — including combinations of red and blue — to boost photosynthetic growth and ultimately the plant’s potency. That use is sometimes ratcheted up in winter's darkest months.
The spillover effect is greatly enhanced by snow, fog, and low clouds.
It can also be obscured with blackout curtains on growhouse windows, the kind one Cumberland County producer intentionally dropped during last year’s Breast Cancer Awareness Month to paint the sky pink.
Of course this light pollution has its critics, and at least one U.S. county, Humboldt in California, has a law on the books saying light "shall not escape [a cannabis grow operation] at a level that is visible from neighboring properties between sunset and sunrise."
The Pennsylvania law governing the production of medical marijuana — the only legal form of the drug here — largely defers to local zoning rules, which remain a highly variable patchwork.
Why do the commonweath's cultivators use transparent greenhouses instead of opaque warehouses in the first place? It's cheaper, allowing natural light in, which helps to lower energy and production costs.
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—Colin Deppen, PA Local editor | 
