Finally, here in Seattle, there was a decent thunderstorm worthy of recording! I used my Sony PCM D50 digital recorder with a towel over the built-in microphones to reduce wind noise. This recording was a 24 bit wav file at 48 kilohertz. Then I transferred the file to my computer and used Adobe Audition for some clipping restoration (on the loudest peaks), boosted the high frequencies about 3.5db, and added fades at the beginning and ending. In addition, I tried to keep the dynamics as wide as possible for a more lifelike sound. Someday I may have this file available for downloading. For now it is an mp3 at 320 kilobits, 48 kiloherts, 16 bit. I used RazorLame with the LAME encoder for the highest possible quality mp3.

 PCMD50-small

rain thunder 9-15-2013 24 bit wav file in Adobe Audition-unprocessed(small)wav file in Adobe Audition 24 bit, 48 kilohertz unprocessed from recorder

rain thunder 9-15-2013 24 bit wav file in Adobe Audition(small)wav file in Adobe Audition 24 bit, 48 kilohertz peak level -.33db