• The fog that disrupted the lives of people in North India is a common weather phenomenon. A fog is a collection of small droplets of water produced when evaporated water has cooled down and condensed.
  • High humidity, combined with an ample presence of water vapour or moisture, encourages foggy conditions.
  • When cooler weather kicks in, this mass of warm, moist air comes in contact with processes that cool it. The ‘collision’ prompts the water vapour in the air to condense rapidly, giving rise to fog.