What does contrail mean?
A contrail is the long, thin cloud of ice crystals that forms in an aircraft's wake when water vapour from hot engine exhaust condenses and freezes in the cold air of high altitude — typically above about eight kilometres (26,000 feet). The name is a shortened blend of 'condensation trail', and the phenomenon is also known more traditionally as a vapour trail. Contrails usually appear as crisp white lines that may fade within seconds or, in humid conditions, persist for hours and spread into wispy sheets resembling natural cirrus cloud. Because these spreading contrails can trap heat in the atmosphere, they are of genuine interest to climate scientists, who study their contribution to aviation's overall warming effect. Beyond aviation, similar streaks can be produced by wingtip vortices, propellers, and rockets. The term is neutral and technical, used widely in meteorology, aviation reporting, and everyday description of jet-streaked skies.
nounA visible trail of condensed water vapour left in the sky by an aircraft engine or by the airflow around its wings, typically at high altitude.
- A trail of condensed water vapour produced by aircraft engines at high altitude.
- A similar cloud-like streak produced by the airflow around wings, propeller tips, or rocket exhaust.
"A single contrail stretched across the evening sky, marking the path of a distant jet."
"From the control tower we watched a fresh contrail form behind each passing airliner."
"On clear cold mornings, the sky over the airfield was laced with contrails from the overnight transatlantic traffic."
Regular plural; frequently used when describing several trails across the sky.
"Dozens of contrails criss-crossed the horizon by midday."
Those white streaks jets leave behind aren't smoke — they're man-made clouds, and on busy flight paths they can spread into sheets of cirrus that measurably affect the climate.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of contrail
Contrail is an American coinage of the mid-20th century, formed as a clipped compound of 'condensation trail' during the era of expanding high-altitude aviation, around the time of the Second World War. It belongs to a family of English compounds built on 'trail', a word of Middle English origin ultimately derived from Old French 'trailer' (to drag or draw along). Its sibling abbreviation 'vapour trail' predates it and remains common in British usage, while 'contrail' has become the standard international term in aviation and meteorology.
Related word forms
How contrail is actually used
A modern technical and aviation term, neutral in tone. The word is standard in both British and American English, with 'vapor/vapour trail' as the older, more traditional alternative. In climate science contexts, 'persistent contrails' is a common phrase referring to trails that linger and spread.
Easily confused with contrail
A chemtrail is the name of a conspiracy-theory claim that some aircraft trails contain deliberately sprayed chemicals, whereas a contrail is the scientifically documented condensation trail formed naturally by water vapour from aircraft exhaust.