The picture above was taken at the Chicago Water Intake, which is about 2.75 miles offshore of the downtown. At the time of the picture (4:10 pm CDT), the temperature was 73.4°, the dewpoint was 73.4°, the relative humidity was 100% and the wind was northeast at 15 mph.
The air was coming off the lake and forced to lift to get over the tall buildings. As it lifted, the air cooled a wee bit and we had a cloud form. Despite the wind, the cloud would remain stationary over the tall buildings, just like it would if there was a mountain there. Check out this video. It’s a stationary lenticular cloud over Mt. Rainier in Washington State. Despite the wind blowing from right to left, the cloud remains in the same place.
Here’s a nice evening picture of Chicago just after sunset. I like the deep blue water. Most of the time, the air is too dry for this cloud to form over Chicago, but not today. The wind really shifted around at the intake. At 4 am the wind was south, then northwest at 5 am, north at 6 am, southeast at 7 am, south at 8 pm, west at 9 am, south at 10 am, southeast at noon, southwest at 1 pm, northeast at 3 pm, south at 6 pm and southeast at 7 pm. Forecast that for the boaters.