February - halos You are here: Home Photo gallery Atmospheric optics Twilight phenomena Afterglow

The afterglow is an intense red glow of the atmosphere long after sunset (or long before sunrise), when most twilight colors should have disappeared. The afterglow is caused by dust in the high stratosphere, which catches the hues of the twilight arch below the horizon. The afterglow is commonly seen during or after volcanic eruptions, which deposit large amounts of dust and ash into the high atmosphere. Spectacular twilight phenomena were reported for years after Krakatoa's eruption, around 1882-1885.

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