The Broomstick Vapor Trail

Wednesday, March 25, 2009

On my way home Monday night, a clear sky, stars visible from downtown Toronto. Away up above me a commercial jet plane makes its way from west to east, leaving a faintly visible vapor trail as it passes overhead. A lovely sight, with the plane’s lights winking and blinking as people sip their coffee at 32,000 feet, give or take.

I consider the plane’s motion, that being a jet plane, it gets its forward velocity from the reaction of the hot gases which push the plane forwards as they escape backwards. You have released an inflated balloon and observed the same principle.

The vapor trail is the visible sign of the work being done away up there. Without the burnt fuel, there’d be no reaction, and there’d be no forward motion; the plane would still be sitting on the tarmac in Vancouver.

The vapor trail represents, no, IS, the stuff that pushes the plane forwards.

And yet I think of a vapor trail as a collection of extremely small and disconnected ice particles.

It is difficult to consider that the vapor trail is pushing the plane forward, as much as would a wooden broomstick (albeit a large one!) glued to the plane’s rear-end.

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