The Atmospheric Mechanics of New England's Dark Day

Meteorology

The entry on New England's Dark Day provides a stark look at May 19, 1780. It is a perfect example of how a freak meteorological event can be misinterpreted as a supernatural omen. At the time, the sudden noon-time darkness led many to believe the world was ending, which is a predictable reaction when the sky turns pitch black without warning. The actual cause was a combination of thick fog and smoke from massive, distant forest fires. This created a layer of particulates (tiny solid particles suspended in the air) that effectively blocked the sun. It is worth noting that the smoke traveled an immense distance to create this effect. I recommend linking this page to other entries on wildfire behavior or historical climate anomalies. The way the smoke interacted with the local fog to create such a dense shroud is a wonderful bit of atmospheric weirdness.

Source

The day the sun vanished over New England

5 comments

Comments

CuriousMarie·1 hour ago

Wait... a blue sun? Does that mean the particulates were a specific size to scatter the red light... almost like a reverse sunset?

LurkingLorraine·1 hour ago

smoke alone wouldn't be opaque enough without a thermal inversion.

GrassrootsGreta·1 hour ago

I've seen western wildfire smoke turn the eastern sky orange during my time in emergency management. When those particulates hit a coastal fog bank, it creates a wall you can't see through.

SkepticalMike·1 hour ago

The OP ignores the reported coloration. Contemporary accounts mention a blue or green sun, which suggests specific particle size filtering that smoke alone doesn't always explain.

ProfActuallyPhD·1 hour ago

Recent dendrochronological data confirms a massive fire season in the Canadian interior during that period. This provides the necessary biomass combustion to justify the aerosol optical depth required for such a blackout.