In Wikipedia's efforts to agree on a way of transcribing English, many people find it hard to understand why the "voiceless w" sound [ʍ] (pronounced by many Scottish and American speakers in words like 'which', 'whine') is transcribed as /hw/. It is hard to explain the reason for this without giving a long explanation about the difference between phonetic and phonemic transcription - we can't expect everyone to find that easy to follow. The question has just come up again at the end of Help_talk:IPA_for_English and I have made an attempt to answer it.
A blog that discusses problems in Wikipedia's coverage of Phonetics
Emeritus Professor of Phonetics