That evening at the top of Warren Dunes, it was pretty exciting as the inversion was setting-up. And this variation of the speed of light has the effect of bending light rays." “So literally the speed of light varies within the air. “A mirage is just a case of atmospheric refraction, it’s caused by the fact you have temperature variations in the atmosphere and these cause density variations.” says Doctor Mark Rennie, an associate professor in areo-optics at the University of Notre Dame. That something is a strong temperature inversion, warmer air above colder air, that causes light to bend. “Anything more than that, especially when you get above 10 or 12, something's happening, because that's not usually there," Nowicki said. Yes, you can see Chicago, just not all of it. On a normal sunny day, say in summer you can only see a dozen or so of Chicago’s tallest buildings from southwest Michigan. “Earlier this year there was a good opportunity, It looked like 40 or 50 buildings which is the most I've ever had the chance to see." Here at Warren dunes you have a better chance at seeing Chicago, up at St. Looking towards the south less than 20 miles away you can see Michigan City, the power plant and Blue Chip Casino. That day on the shores of Lake Michigan at Warren Dunes State Park, just 50 some miles to the west, Chicago was hard to see on the slightly overcast day. Doing the same calculations you could see it from up to 65 miles away on Tower Hill. The Willis (Sears) Tower is 1,450 feet to the top. That’s still not far enough to see Chicago, at least at ground level.
If you climb to the top of Tower Hill (250ft) you can see almost 20 miles to the horizon. Someone that’s six feet tall standing on the lake shore can only see about three miles to the horizon. The distance from Warren Dunes state park is about 53 miles across the lake to Chicago.