Airplanes flying sufficiently high overhead, where the temperature is −40 °C or colder, will leave familiar condensation trails, or contrails, as water vapor expelled in the plane’s exhaust forms droplets or ice particles. But that is not the only effect that planes leave in their wake. Planes passing through midlevel clouds can induce linear voids, known as canal clouds, and circular voids, called hole-punch clouds or fallstreak holes. Seen here is a hole-punch cloud over the West Antarctic ice sheet in December 2009. Gray streams of ice—the fallstreaks—are visible below the hole, which formed near the horizon and moved toward the camera. The hole was likely caused by a Lockheed LC-130 four-engine turboprop.
Hole-punch and canal clouds have been associated with aircraft since the late 1940s. Now Andrew Heymsfield of the National Center for Atmospheric Research and colleagues have combined observational data and computer simulations to gain new insight into...
