6.4 Anomalous cloud lines over the Chesapeake and Delaware Bays

Saturday, 27 May 2000: 11:15 AM
Todd D. Sikora, U.S. Naval Academy, Annapolis, MD; and E. O'Marr and R. Gasparavic

Anomalous cloud lines over the Chesapeake and Delaware Bays have been observed in numerous National Oceanic and Atmospheric Administration Advanced Very High Resolution Radiometer (AVHRR) images. An dramatic example of such phenomena can be seen in Fig. 1. Figure 1 is an AVHRR image from 11 October 1996 at 11:44 UT. Two distinct cloud lines can be seen protruding from the Chesapeake and Delaware Bays. Since 1996, AVHRR imagery from over the Chesapeake and Delaware Bays have been archived by the Johns Hopkins University Applied Physics Laboratory Ocean Remote Sensing Group. The authors have reviewed over a year's worth of this data and have found more than 40 cases of cloud lines similar to those found in Figure 1.

Local National Weather Service Forecasters are aware of these cloud lines and they have speculated that the phenomena are the result of thermal plumes over the Bays during cold-air outbreaks. While this hypothesis is plausible, there is evidence that the cloud lines are due to another cause. Ship tracks. This evidence comes from the fact that the origins of at least several of the documented cloud lines correspond with the location of ships steaming through the bays. Additional evidence are periodic geometrical irregularities in the many of the cloud lines. An example of such an irregularity can be seen in the Atlantic Ocean for the cloud line associated with the Delaware Bay. Several sharp angles are apparent. This research is ongoing and investigation of the remaining data set continues. No conclusions as to the cause of the cloud lines have yet been made.

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