Approaching thunderstorm with lead gust front. Rain-cooled air from the storm moves out ahead of the storm. It ploughs under the warm moist air forming a flat"shelf cloud."

Image ID: nssl0045, NOAA's National Severe Storms Laboratory (NSSL) Collection
Location: Brookhaven, New Mexico
Photo Date: 1982
Credit: NOAA Photo Library, NOAA Central Library; OAR/ERL/National Severe Storms Laboratory (NSSL)

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