Rule 5b. Never use single quotation marks in sentences like the previous three. Incorrect: I had a visit from my 'friend' the tax man. The single quotation marks in the above sentence are intended to send a message to the reader that friend is being used in a special way: in this case, sarcastically. Avoid this invalid usage.
Why do jets leave a white trail in the sky? Jets leave white trails, or contrails, in their wakes for the same reason you can sometimes see your breath. The hot, humid exhaust from jet engines mixes with the atmosphere, which at high altitude is of much lower vapor pressure and temperature than the exhaust gas.
Chemtrails: Are Planes Spraying Chemicals Into The Sky Officially, they are vapor trails - but is there something more sinister to the plane trails in the sk... Chemtrails: Are Planes Spraying Chemicals Into The Sky Officially, they are vapor trails - but is there something more sinister to the plane trails in the sk... Skip navigation Sign in