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Where on Earth: Heat Island in India

Where on Earth are these fog holes?
Credits

Produced by the Space Telescope Science Institute’s Office of Public Outreach in collaboration with the NASA Earth Observatory (https://earthobservatory.nasa.gov/).

Story adapted from Image of the Day post by Kathryn Hansen: https://earthobservatory.nasa.gov/images/91742/urban-heat-islands-punch-holes-in-fog

  • Image of Northern India (2014) from Moderate Resolution Imaging Spectroradiometer (MODIS), on Terra satellite
  • Image of Fog Holes and Urban Heat Islands in India from the Moderate Resolution Imaging Spectroradiometer (MODIS), on Terra satellite
  • Developed Land map side by side to Temperature map; Urban Heat Island Effects (Baltimore, Maryland) from National Land Cover Database, Landsat 7
  • Image of New Delhi from lower altitude, from Operational Land Imager, Landsat 8
  • Written by Katherine Porter
  • Designed by Dani Player
  • Music from Yesh Music (ASCAP)
Transcript

(SPEECH)
[GENTLE MUSIC]
 
(DESCRIPTION)
Collage of distinct satellite images of natural phenomena.
 
Text, where on earth? Satellite image, a mountainous terrain with snow on one side and a swath of fog on the other.
 
Text, This satellite image shows a wide area of land partially covered by fog.
 
In places, distinct holes in the fog layer reveal the ground beneath. Circles appear around the holes.
 
Text, where are these fog holes? A, above cities in India, B, above volcanoes in Chile, C, above swamps in Australia, D, above farms in the United States.
 
A is highlighted, above cities in India. Labels appear on map. New Delhi.
 
Text, fog holes and urban heat islands in India. Peculiar holes in a layer of fog over northern India seem to correspond with the locations of major cities. Researchers suspect that they are a result of the urban heat island effect.
 
Urban Heat Island Effect, Baltimore Maryland. Large portions of urban areas are covered in heat absorbing surfaces, such as pavement and roofing. As a result, cities tend to heat up faster and stay warmer longer than surrounding rural areas. Images of Baltimore reveal the sprawling effect of temperature in developed land.
 
Image, a large green hole in the fog over New Delhi. Text, Fog holes and Urban Heat Islands in India. Fog formation requires a stable layer of moist air near the ground with temperatures low enough for the moisture to condense.
 
Even when there is enough moisture in the air to form fog in cool rural areas, the temperature in the city may be too high. In the cities, fog dissipates quickly or does not form at all.
 
India is not the only place where the effect has been observed. Fog holes have also been spotted over China, Europe, and the United States.
 
The map recedes until we have the whole Earth before us. Text, Music courtesy of Yesh Music A S C A P.
 
Where on earth?