Envirocast® Bulletin for January 31, 2007

Aircraft Dissipation Trails and "Punch Holes"

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The images in this Envirocast® Bulletin were taken by the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard NASA's Terra satellite on January 29, 2007. They show aircraft dissipation trails and "punch holes" over the southern U.S.

Aircraft Dissipation Trails and "Punch Holes" Over the Southern U.S.

The image above was captured by NASA's Terra satellite when it flew over the southern U.S. on January 29, 2007.  Numerous aircraft dissipation trails are clear in this image. A dissipation trail, the opposite of a condensation trail but comparatively rare, is a clearly delineated limpid lane forming behind an aircraft flying in a thin cloud layer.

 

The MODIS image also shows a number of round holes in a blanket of cloud cover over Oklahoma, Arkansas, Louisiana, and Texas. A few of the “holes” are elongated, with what appear to be smaller clouds inside them.

Zoom-in View of Dissipation Trails and "Punch Holes"

In this zoom-in view, the diameters of the "punch holes" extended to as much as 5 miles.

 

Ground Photo of a "Punch Hole"

Ground photo taken by inhabitants in the Cajun heartland in southern Louisiana on January 29, 2007 show this unusual cloud formation -- "punch hole".

Environmental Impacts:

  • A dissipation trail, the opposite of a condensation trail but comparatively rare, is a clearly delineated limpid lane forming behind an aircraft flying in a thin cloud layer.

  • The MODIS image also shows a number of round holes in a blanket of cloud cover over Oklahoma, Arkansas, Louisiana, and Texas. A few of the “holes” are elongated, with what appear to be smaller clouds inside them.

  • This strange phenomenon resulted from a combination of cold temperatures, air traffic, and perhaps unusual atmospheric stability. The cloud blanket on January 29 consisted of supercooled clouds. Supercooled clouds contain water droplets that remain liquid even though the temperature is well below freezing, and such clouds are not unusual. According to the Cooperative Institute for Meteorological Satellite Studies (CIMSS) Satellite Blog, cloud-top temperatures ranged from –20 to –35 degrees Celsius (-4 to -31 Fahrenheit). As aircraft from the Dallas-Fort Worth airport passed through these clouds, tiny particles in the exhaust came into contact with the supercooled water droplets, which froze instantly. The larger ice crystals fell out of the cloud deck, leaving behind the “holes,” while the tiniest ice particles in the center remained aloft.

  • The people on the ground watching the show these clouds made didn’t have to worry about getting wet or being showered with ice. When the general atmospheric conditions aren’t favorable for rain, the falling ice crystals sublimate—change state directly from a solid to a gas—as they pass through warmer layers of the atmosphere.

  • Thanks to J. Marshall Shepherd, University of Georgia, for image interpretation.

Supplementary Material:

NASA's TERRA Satellite:

  • The Terra spacecraft (formally known as EOS-AM) was successfully launched on Saturday, December 19, 1999 at the Vandenberg Air Force Base (VAFB) in Lompoc, California. It is flying at an altitude of 705 km (438 miles) observing the Earth. The life expectancy of the Terra mission is 6 years. It will be followed in later years by other EOS spacecraft that take advantage of new developments in remote sensing technologies. [Terra 3D Animation], [Animation showing Terra Orbit]

  • Terra's orbit around the Earth is timed so that it passes from north to south across the equator in the morning, and thus it passes over us at the same local time every day, approximately 10:30-10:45 a.m.

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MODIS image shows aircraft dissipation trails over the southern U.S. on January 29, 2007.
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Same as above (with state names).
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Same as above (with state boundaries).
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Same as above (with no annotation).
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Zoom-in view to dissipation trails and "punch holes".
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Ground photo of a "punch hole".

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MODIS image shows aircraft dissipation trails over the southern U.S. on January 29, 2007.
Image NTSC 640x480

Same as above (with state names).
Image NTSC 640x480

Same as above (with state boundaries).
Image NTSC 640x480

Same as above (with no annotation).
Image NTSC 640x480

Zoom-in view to dissipation trails and "punch holes".
Image NTSC 640x480

Ground photo of a "punch hole".

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