Monday, June 7, 2010

Satellite imagery for dummies

  • Time in all satellite images are given in Z or Zulu or GMT. Please add 5:30h to it to convert it to IST. Also even though the images are updated every 30mins, processing the images takes a little time so the latest images that you see are around 1hr old.
  • The infrared (IR) images provide information about the temperature  of the clouds. The coldest (therefore the tallest) clouds such as cirrus, cumulonimbus appear white whereas the warmer clouds will appear grey.
  • The visible images are the reflection of the solar radiation from the clouds and obviously can only be seen during the day.
  • Meteorologists have to see both the visible and IR images to derive a correct interpretation of the clouding.
  • My own favourite sites for checking the very latest IR images are the US navy site which is here and the IMD Kolkata site which is here
Comment by Praful Rao
My thanks to my good friend and IAF course mate Dr B Nandi (Ph. D), an outstanding meteorologist, for the guidance and help not only for the above article but also whenever I need an expert opinion on meteorological matters.

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