My trip to the mailbox this morning began peacefully enough, a quiet stroll through a slowly brightening day. Then I looked up. The sun hung in a hazy sky, its light filtered by particulates from fires in Quebec, leaving a visible disk that looked like a second moon. The smoke changed the usual morning light from bright yellow to a darker, ruddier hue. Very dramatic.
Today’s forecast? Thunderstorms, which brought to mind the old adage about skies and sailors. “Red sky at night, sailor’s delight. Red sky in morning, sailor’s warning.” It turns out to be based on atmospheric science, and while the logic doesn’t hold up everywhere all the time (and yes, smoke can interfere with its accuracy), it can be useful.
Red Sky at Night: Is the Sailor’s Saying Really True?
The folklore lines up with two pieces of plain physics: how air moves and how light scatters. Low pressure pulls air together and lifts it, which builds clouds and brings rain. High pressure does the opposite. Air sinks and spreads out, which keeps the sky clear and traps dust and fine particles near the ground. Sailors learned the shorthand long before anyone measured a millibar: low pressure for foul weather, high pressure for fair.
Happily, forewarned is forearmed (to use another old adage). Now I wait, and watch for the coming storm.
A red sun rises.
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