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A partial calque of German Alpenglühen (literally “glow of the Alps”), with the second element replaced by the English equivalent glow.
Etymology from Wiktionary, CC BY-SA 4.0.
alpenglow
al·pen·glowToday it means: A rosy or reddish glow seen during sunset or sunrise on the summits of mountains, especially snow-covered mountains on the opposite side of the sun. Full definition →