15 November 2006 - AWIPS MODIS Images
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Aircraft Distrails Over Southern Wisconsin
The following points can be made by examining the various 15 November 2006 MODIS images and products over southern Wisconsin:
- Visible channel: Multi-layered cloudiness was present over much of the region, with a short northwest-to-southeast oriented aircraft dissipation trail ("distrail") noted to the northeast of Wisconsin Dells (KDLL)
- Snow/Ice (2.1 um) Channel: The aforementioned linear distrail segment (plus a looping distrail segment between KDLL and Madison KMSN) exhibted a darker signal, which suggests the presence of ice particles. The remainder of the cloud deck covering most of southern WI showed a brighter signal, suggesting cloud composed primarily of supercooled water droplets
- Shortwave IR (3.7 um) Channel: The aircraft distrail features exhibted a brighter (colder) signature, indicative of either a phase change to ice or a change to smaller cloud particle sizes
- Cirrus (1.3 um) Channel: The relatively bright signal over much of southern WI suggests a cloud deck that is primarily composed of supercooled water droplets
- IR Window (11.0 um) Channel: Only patchy areas exhibited cloud top temperatures colder that -30 C (yellow enhancement)
- Cloud Top Temperature product: Cloud top temperatures were generally -30 to -40 C over much of southern WI
- Cloud Phase product: The bulk of the cloudiness over southern WI was flagged as "Ice phase"
It is felt that the aircraft distrails were formed within a mid-level supercooled cloud deck, causing portions of that cloud layer to glaciate. In addition, a thin veil of higher-altitude cirrus clouds also covered the region, and it was this cirrus cloud layer that showed up as the large area of -30 to -40 C values on the Cloud Top Temperature product and the corresponding extensive area of "ice phase" on the Cloud Phase product.
Java applet developed by Tom Whittaker, CIMSS / SSEC
Back to the 15 November 2006 "Hole punch clouds" and aircraft "distrails" blog entry