Shadow-powered billboard addresses solar

Using solar power to make effective advertising, WWF is once again heating things up. A fairly simple setup, a billboard with an awning casts a shadow during the day that corresponds with the marketing message. Previously, WWF created an ad that also held a very shocking visual of the tangible amount of carbon monoxide we create in one day's worth of driving. Trendhunter points to further explanation of the billboard:

"It’s perpendicular to the equator, with an unobstructed exposure to the west. The “waves” start at about 12:00. The challenge was not azimuth (the daily path of the sun), but altitude, which due to the Earth’s tilt, required the scalloped awning’s shape to be distorted to compensate for 43N latitude, during the life of the posting (about 8 weeks)."