Someone turned Chicago’s green river into a giant ‘chroma key wall’

Every year, the Chicago River is dyed green for St. Patrick’s Day — and this year someone realized the green water was the perfect giant “chroma key wall.”

Somewhat ironically, meanwhile, most TV weather forecasters can’t wear green on air to mark the holiday because the color conflicts with their station’s key wall (though as more stations switch to video walls for weather, green is finding its way back into the wardrobe of some weather people).