For most of the past week, much of lakefront Chicago has been shrouded in a very thick, very eerie fog like something out of a horror film, allowing the bulk of its iconic skyline to pull a vanishing act.
The situation has a relatively simple weather explanation but has, nonetheless, set the scene for some incredible photos of the city.
AccuWeather meteorologist Frank Strait explained to the Chicago Sun-Times that the extremely foggy conditions are largely due to the fact that Lake Michigan remains unusually cold for this time of year -- the result of the historic, record-breaking "polar vortex" the city experienced this winter.
In addition, Strait said, when the high-moisture air mass currently over the region moves over the lake, it causes fog to develop rapidly. From above, it looks like a giant cotton ball has swallowed up the city:
According to the National Weather Service, the city has seen quadruple the normal amount of fog and low cloud cover in recent days, the Chicago Tribune reports.
The foggy conditions caused a number of flight delays and cancellations at Chicago's Midway and O'Hare airports.
Other cities along the still-chilly Great Lakes have also seen much more fog than usual for the same reason.
Duluth, Minnesota, has also been coated with fog:
As has Muskegon, Michigan: