Potential Distrails Over Northern Lake Michigan
A somewhat unusual feature was visible off of the coast of Wisconsin’s Door Peninsula on 15 December 2025. Bands of clouds were separated by narrow, tight corridors of clear air. Such straight lines are not common for natural features in the atmosphere, which hints that they may be anthropogenic in nature. The highest resolution geostationary view is found in GOES-19 ABI Channel 2, which is nominally 0.5 km at the sub-satellite point. The following animation depicts the evolution of the structure throughout the morning and early afternoon.
One potential explanation for this phenomenon is a set of distrails. Many people are familiar with contrails (short for “condensation trails”), the linear clouds produced from the exhaust of aircraft traveling at high altitudes. A common byproduct of combustion is water vapor, and if a flight is taking place in a saturated layer of the atmosphere, the water vapor produced by the plane’s engines will deposit into ice crystals.
Distrails, short for “dissipation trails,” are effectively the opposite of contrails. Instead of forming when a plane flies through clear sky, distails form as a plane flies through a supercooled liquid cloud. Two separate mechanisms can be at work here: first, the hot exhaust causes evaporation of the existing cloud droplets, and second, the exhaust particles of the aircraft engines serve as condensation nuclei forcing the existing water vapor to condense and precipitate toward the surface. Regardless of the mechanism at work, the end result is a long, narrow region of clear air within an existing cloud.
The day cloud phase distinction RGB can help provide a little more information on this structure, albeit at the cost of worse spatial resolution since we have to bring in the 1-2 km infrared bands to make this product. Here, we see that the preexisting clouds are lavender, which means they are likely lower level liquid clouds. Given the ambient weather conditions in the upper Midwest at this time, it’s all but certain that those are supercooled liquid clouds. An airplane flying through these clouds could easily disturb the saturated equilibrium and force the dissipation of the clouds.
One other valuable tool for this investigation is VIIRS. This polar-orbiting instrument doesn’t have the constant presence of the GOES ABI, but it makes up for it with higher spatial resolution. An overpass from NOAA-20 at 1745 UTC (11:45 AM CST / 12:45 PM EST) was perfectly timed to capture this event in true color.
