Ozone: a stratosphere story

  • Exhibition Text

    • At the Earth’s surface, ozone is a pollutant, but its presence in the stratosphere is critical in protecting life. Formed by a complex chain of reactions, ozone absorbs harmful ultraviolet radiation from the Sun, preventing it from reaching the Earth’s surface. Stratospheric ozone is increasingly being destroyed by man-made pollutants.

      The ozone hole
      Ozone holes are regions in the stratosphere where little ozone remains. They develop annually over the Antarctic and the Arctic. Ozone holes form over the polar regions because the circumpolar air currents concentrate the ozone-destroying chemicals there. In addition, ice particles accelerate the reactions that destroy ozone by providing surfaces on which the chemical reactions can take place. With each year since their discovery in the 1980s, the polar ozone holes have grown larger. In the mid-latitudes, the ozone layer has also been thinning noticeably. 

      Volcanism and the atmosphere
      Explosive volcanic eruptions inject volcanic gases high into the atmosphere. One of these gases, sulfur dioxide, forms tiny droplets known as aerosols, which have an important effect on climate and on ozone. The aerosols reflect some solar radiation back into space, causing the Earth’s surface to cool — an effect that typically lasts for years. The aerosols also hasten the depletion of the ozone layer by providing surfaces on which ozone-destroying reactions take place.

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  • For Educators

    • Topic: Earth Science

      Subtopic: Atmosphere

      Keywords: Chlorofluorocarbons, Climatology, ultraviolet radiation, ozone layer, Ozone hole

      Audience: General