Distrails Distract Distress
If it seems contrails are getting a lot of negative publicity of late, let’s not overlook so-called “negative contrails” known more properly as distrails. Short for “dissipation trails”, these curious clear channels through clouds are much rarer than contrails because they require a stricter set of atmospheric conditions to form.
In a nutshell, distrails form when aircraft fly through thin clouds. The hot aircraft exhaust converts a long swath of water droplets back into invisible water vapor – sort of a contrail in reverse. Distrails typically “fill in” with clouds much faster than contrails fade, though, as internal combustion engine and jet engine exhaust quickly cools down to the ambient air temperature.
Will contrails someday be seen as more than just a pretty phenomenon and instead, a deleterious instigator of climate change? Mechanisms that work to inhibit contrail formation are at present beyond the capabilities of our technology, even if they were required by legislation, and grounding all commercial passenger aviation is only doable in emergency situations like the post-9/11 grounding. Hopefully clearer minds unclouded by political and economic pressures will be able to take action when the time comes.
In the meantime, we can all appreciate the splendor of the above image, captured in 1989, of two F-15 fighter jets intercepting a pair of Soviet MIG-29’s over Alaska – a photograph whose beauty is dependent on the jets’ distinct contrails.

