Brocken specter

[Erik T. Burns]

https://www.bbc.com/news/uk-england-derbyshire-59741101

As the sunlight strikes their backs, coming in nearly flat on, it begins
developing on the pearl cloudbank: two gigantic shadows, thrown miles
overland, past Clausthal- Zelterfeld, past Seesen and Goslar, across where
the river Leine would be, and reaching toward Weser. . . . "By golly,"
Slothrop a little bit nervous, "it's the Specter." You got it up around
Greylock in the Berkshires too. Around these parts it is known as the
Brockengespenst.