You certainly don’t see something like this every day.

On Tuesday, South Dakotans witnessed a unique weather phenomenon spread out over the state — the sky turned green.

Earlier this week, storms passed through South Dakota, leaving behind considerable rainfall, hail, and wind reports. However, the most unique portion of the severe weather came in the form of an ominous green sky that left residents amazed.

The hue covered the South Dakota hub of Sioux Falls throughout the late afternoon hours.  

Many people took to Twitter to share photos of the eerie phenomenon, with cloud-darkened skies whipping up a nearly photosynthetic hue.

A report from “Sioux Land” explained why the sky turned green:

As a storm front moved into South Dakota on Tuesday, and the night seemed to fall early as 3:00 p.m. saw dark skies cast into a deep and eerie shade of green.

What causes this foreboding shade of green? According to, the sky normally appears blue due to the process of refraction. “During the day, particles in the air scatter more violet and blue light, and our eyes are more sensitive to blue.”

Meteorologist Scot Mundt said that this same process produces a green sky, with the addition of one important ingredient.

“It’s caused by the sun’s rays being refracted by the hail (inside the storm) as the rays pass through the cloud,” Mundt explained. “It’s the same concept of how a rainbow forms. The sunlight is refracted as it passes through the raindrops, resulting in a rainbow.”

More details of this unique weather phenomenon as reported by the “Euro News”:

The skies above South Dakota, US turned green on Tuesday (5 July) as a particularly strong storm rolled in.

Eerie images appeared on social media showing the peculiar colour of the sky over Sioux Falls, South Dakota just before a thunderstorm swept through the area.

The National Weather Service confirmed that a ‘derecho storm’ barreled through much of South Dakota, Minnesota and Iowa, leaving nearly 30,000 people without power for hours.

Storms qualify as derechos when they have sustained winds of at least 93 km/h and leave a path of damage at least 400 km long, according to the National Weather Service. This particular storm reached a wind speed of 159 km/h.

While residents in South Dakota have grown used to derechos having recently experienced two such storms, the green sky was a highly unusual sight.

Still, if you were lucky enough to witness the stunning skies from the comfort of your own home, it must have been fascinating.

“The sunset and everything played with the lighting too and some people said it was the most incredible thing they’ve ever seen,” Karins said.

Sources: WLT, Euro News, Sioux Land

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