lakeside mi gwen1.jpeg

Gwen Williams took this picture this April, 2015 from Lakeside, MI. She says she cannot normally see the Chicago skyline, but on this day it was clearly visible.

(Gwen Williams)

Keep your eyes open for strange 'mirages' on the Great Lakes this weekend, and even all next week.

This is the time of year when warmer air over cold water can create some amazing views. It's this type of atmospheric condition we should have in Michigan and over the Great Lakes in the next week.

These mirages usually are seen on the West Michigan shoreline, looking west toward Chicago and Milwaukee. Some very strange sights can occur.

The mirage usually manifests itself as being able to see the Chicago skyline clearly from the Lake Michigan shore, or see lights from Chicago and Milwaukee at night.

The reasons are atmospheric conditions called refraction and ducting. Light rays travel different from normal when atmospheric conditions are much different from normal. Normally the warmest air is near the ground, and the air cools higher in the atmosphere. That situation allows light rays from an object to travel higher in the sky with distance. So we don't see the Chicago skyline normally from Michigan.

But at this time of year we get a strong temperature inversion over Lake Michigan. The temperature profile of the atmosphere is opposite of normal. The air right on the lake surface is cold, and the air gets warmer as you go higher in the atmosphere. So a channel of air develops a 'duct' that light rays can keep trapped in. Instead of the light rays going higher in the sky, and you not seeing farther on the horizon, light rays are kept closer to the ground. So the view of objects far off in the distance is visible.

But even stranger views can occur. Depending on how the light rays and view of an object is bent toward the earth, an object can also appear upside down. Rarely it has been reported that people see the Chicago skyline, with another view of an upside-down Chicago skyline above the normal skyline.

The view can change right before you eyes. If the temperature configuration is changing while you are looking at the mirage, you could see the view changing back and forth between a "normal" looking Chicago skyline and an upside-down view of Chicago.

Now if you see this you won't immediately rush to your doctor.

Clear, sunny skies with a light wind and slowly warming temperatures are the conditions I've found to create this spectacular view. That's the weather we should have most days over the next week.

If you see this condition, take a series of pictures and share below. Since this is a real condition, and not an "illusion", you will be able to photograph the phenomenon.

MLive Chief Meteorologist Mark Torregrossa has been forecasting Michigan weather for more than 25 years. He's been chief meteorologist at three television news stations in Michigan, and he's an avid gardener and hunter. Email him at mtorregr@mlive.com and find him on Facebook at facebook.com/mark.torregrossa and Twitter @weathermanmark