rarefied air molecules

[mknutson]

anacoustic zone
The region of Earth's atmosphere where distances between rarefied air molecules are so great that sound waves can no longer propagate. Also known as the zone of silence.

[seekfun]

MKnutson,

Thanks for sharing. This was incredibly interesting, and the article reminded me of the book Magnificent Failure, about Nick Piantanida's efforts to jump from a balloon in the Stratosphere.

[url="http://www.amazon.com/Magnificent-Failure-Free-Fall-Space/dp/1588341410"]Amazon.com: Magnificent Failure: Free Fall from the Edge of Space (9781588341419): Craig Ryan: Books

Cheers,

topher