Explained: How the ozone layer hole over Arctic closed

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News:European Union’s Copernicus Atmosphere Monitoring Service(CAMS) has announced that a hole in the Arctic ozone layer believed to be the biggest reported over the Arctic has closed.

Facts:

  • Ozone Hole:It refers to a region in the stratosphere where the concentration of ozone becomes extremely low in certain months.
  • Reason for Ozone Hole: Cold temperatures (below -80°C), sunlight, wind fields and substances such as chlorofluorocarbons (CFCs) were responsible for the degradation of the Arctic ozone layer.
  • Closing of Ozone Hole: Scientists believe that the closing of the hole is because of the polar vortex and not because of the lower pollution levels during the Covid-19 lockdown.

Additional Facts:

Ozone:

  • Ozone layer also called ozonosphere is a layer in the stratosphere lying between roughly 15 and 35 km above Earth’s surface containing relatively high concentrations of ozone molecules(O3).
  • By absorbing the harmful ultraviolet radiations from the sun, the ozone molecules protect earth from harmful UV rays which can cause skin cancer and other diseases and deformities in plants and animals.

Polar Vortex:

  • It is a large area of low pressure and cold air that surrounds the North pole.This air flows in a counterclockwise direction around the Arctic and helps keep the cold air in the North.
  • The Polar vortex always exists near the poles but weakens in summer and strengthens in winter.
  • Hence,during winter, the polar vortex at the North Pole expands, sending cold air southward with jet stream.This happens fairly regularly and is often associated with outbreaks of cold temperatures in the United States.