Astronaut Alex Gerst captured from ISS interesting aircraft contrails.

Credit: Alex Gerst, ESA, NASA

Contrails are produced by jet exhaust. When engines completes a cycle of sucking in -40C air, compressing, combusting and exhausting air, water vapor rapidly crystalizes to form line-shaped clouds. For reference, it is introduced with No.62.

Reference: Alex Gerst’s Tweet
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