VERFEIL (31) 17.02.2013

On 17 February 2013 at 10:04, several people travelling in a car near Verfeil were intrigued by what looked like white trails in a clear sky. The account included 2 photographs. GEIPAN explains that the apparent strangeness arose from the number of trails and the fact that some were not straight. It attributes this to the day’s weather: an emerging autan wind associated with strong winds at altitude, which quickly distorted aircraft contrails, together with temperature and humidity conditions that allowed the trails to persist. The case is classified B: very probable observation of numerous aircraft contrails distorted under an autan-wind regime, with falling pressure and strong upper-level winds.