The white, smoke-like water vapor that follows the path of an airplane is called a contrail. On a clear summer day, you might see several contrails crisscrossing the blue sky.

Pronunciation: /'kɑn,trel/
English Description: a visible mass of water or ice particles suspended at a considerable altitude
Synonyms: condensation trail
Chinese Translation: 飞机云(fei1 ji1 yun2)
Spanish Translation: Estela de vapor
ORIGIN: The next time you see the elongated, cloud-like lines in the sky that linger long after the plane that made them has disappeared, you'll know to call them contrails. They're caused by condensing water vapor from an airplane's exhaust. The word dates from 1945, a shortened version of "condensation trail," and they're sometimes also called "vapor trails."

EXAMPLE SENTENCE:

Water spewed forth from the fountains, their trajectories mirrored in the bright-blue sky by contrails.
We are all familiar with how the exhaust from jetliners alters the atmosphere, forming clouds called contrails—those thin, white streaks across the sky.

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