October 31, 2004
The above photo of a pumpkin orange sunset was taken from El Segundo, California in January of 1992. Many parts of the world experienced vividly colored sunsets for months following the June 1991 explosion of Mt. Pinatubo in the Philippines. The unusually reddened sunsets that often follow volcanic eruptions are caused by volcanic particles suspended in the upper atmosphere, which more effectively scatter the shorter wavelengths (blue and greens) of visible light. Mt. Pinatubo's eruption expelled 18 million metric tons of sulfur dioxide, creating an aerosol cloud that lingered in the upper atmosphere for several years. This massive aerosol load played an important role in lowering global temperatures.