{"id":11604,"date":"2017-02-08T17:53:20","date_gmt":"2017-02-08T16:53:20","guid":{"rendered":"http:\/\/karmaka.de\/?p=11604"},"modified":"2017-02-08T17:54:55","modified_gmt":"2017-02-08T16:54:55","slug":"photoacoustic-sounds-from-meteors","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=11604","title":{"rendered":"Photoacoustic Sounds from Meteors<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"<p>Richard Spalding, John Tencer, William Sweatt, Benjamin Conley, Roy Hogan, Mark Boslough, GiGi Gonzales &#038; Pavel Spurn\u00fd<\/p>\n<p>Scientific Reports 7, Article number: 41251 (2017)<br \/>\ndoi:10.1038\/srep41251<br \/>\nPublished online: 01 February 2017<\/p>\n<p><a href=\"http:\/\/www.nature.com\/articles\/srep41251\" target=\"_blank\"><strong>LINK (OPEN ACCESS)<\/strong><\/a><br \/>\n<a href=\"www.nature.com\/articles\/srep41251.pdf\" target=\"_blank\"><strong>PDF (OPEN ACCESS)<\/strong><\/a><\/p>\n<p>&#8220;Concurrent sound associated with very bright meteors manifests as popping, hissing, and faint rustling sounds occurring simultaneously with the arrival of light from meteors. Numerous instances have been documented with \u221211 to \u221213 brightness. These sounds cannot be attributed to direct acoustic propagation from the upper atmosphere for which travel time would be several minutes. Concurrent sounds must be associated with some form of electromagnetic energy generated by the meteor, propagated to the vicinity of the observer, and transduced into acoustic waves. Previously, energy propagated from meteors was assumed to be RF emissions. This has not been well validated experimentally. Herein we describe experimental results and numerical models in support of photoacoustic coupling as the mechanism. Recent photometric measurements of fireballs reveal strong millisecond flares and significant brightness oscillations at frequencies \u226540\u2009Hz. Strongly modulated light at these frequencies with sufficient intensity can create concurrent sounds through radiative heating of common dielectric materials like hair, clothing, and leaves. This heating produces small pressure oscillations in the air contacting the absorbers. Calculations show that \u221212 brightness meteors can generate audible sound at ~25\u2009dB SPL. The photoacoustic hypothesis provides an alternative explanation for this longstanding mystery about generation of concurrent sounds by fireballs.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Richard Spalding, John Tencer, William Sweatt, Benjamin Conley, Roy Hogan, Mark Boslough, GiGi Gonzales &#038; Pavel Spurn\u00fd Scientific Reports 7, Article number: 41251 (2017) doi:10.1038\/srep41251 Published online: 01 February 2017 LINK (OPEN ACCESS) PDF (OPEN&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[96],"tags":[3643,98,141,3644,3642],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/11604"}],"collection":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=11604"}],"version-history":[{"count":1,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/11604\/revisions"}],"predecessor-version":[{"id":11605,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/11604\/revisions\/11605"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=11604"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=11604"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=11604"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}