Dear Tom,
Why do contrails, which are composed of ice crystals, last so long on a day when ground-level winds are strong and gusty? Aren’t winds at flight level much faster and wouldn’t those winds rapidly blow ice crystals apart?
Robert Fawcet, Cicero

Dear Robert,
Contrails form immediately behind high-flying jet aircraft. Winds at that level are often very strong, but wind speed is not a factor in the dissipation of contrails. Contrails disappear when the ice crystals of which they are composed evaporate. That usually takes a few minutes. It might seem strange what structures as fragile as ice crystals can endure while in an environment of winds sometimes in excess of 100 mph, but they are carried along with the wind. Contrails, like all clouds, move with the wind and that affords a tranquil ride.