Tuesday, 25 January 2011: 11:45 AM
605/610 (Washington State Convention Center)
The Solar Dynamics Observatory (SDO) was launched into orbit atop an Atlas V from SLC 41, Cape Canaveral, FL at 10:23 am EST, February 11, 2010. As it ascended through the atmosphere the Atlas V carrying SDO generated a wave packet that passed near to and destroyed a sundog. This may be the first time a man-made event caused a parhelic display to disappear. An atmospheric sounding taken at Cape Canaveral three hours before launched shows two cloud decks. Other observed atmospheric phenomena, such as a crepuscular ray and a Prandtl-Glauert collar, were combined with videos from several vantage points to pinpoint the layer of the atmosphere where the sundog and waves coexisted. This altitude was 8-9 km, coincident with both the upper cloud deck in the sounding and the altitude of the rocket at the time it was nearly supersonic. The physics of sundogs will be summarized and two ways of destroying the sundog, evaporation and disorientation, will be described. The nature and production of the waves will be discussed.
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