Editing Fog (section)

== Sound propagation and acoustic effects ==
{{see also|Acoustic location|Acoustic shadow|Foghorn}}
Sound typically travels fastest and farthest through solids, then liquids, then gases such as the atmosphere. Sound is affected during fog conditions due to the small distances between water droplets, and air temperature differences.

Though fog is essentially liquid water, the many droplets are separated by small air gaps. High-pitched sounds have a high frequency, which in turn means they have a short wavelength. To transmit a high frequency wave, air must move back and forth very quickly. Short-wavelength high-pitched sound waves are reflected and refracted by many separated water droplets, partially cancelling and dissipating their energy (a process called "[[Damping ratio|damping]]"). In contrast, low pitched notes, with a low frequency and a long wavelength, move the air less rapidly and less often, and lose less energy to interactions with small water droplets. Low-pitched notes are less affected by fog and travel further, which is why [[foghorn]]s use a low-pitched tone.<ref>{{cite web|title=Does fog have a dampening effect on sounds?|url=http://www.thenakedscientists.com/HTML/questions/question/2327/|work=thenakedscientists.com|date=14 June 2009|url-status=live|archive-url=https://web.archive.org/web/20150116132528/http://www.thenakedscientists.com/HTML/questions/question/2327/|archive-date=16 January 2015}}</ref>

A fog can be caused by a temperature inversion where cold air is pooled at the surface which helped to create the fog, while warmer air sits above it. The inverted boundary between cold air and warm air reflects sound waves back toward the ground, allowing sound that would normally radiate out escaping into the upper atmosphere to instead bounce back and travel near the surface. A temperature inversion increases the distance that lower frequency sounds can travel, by reflecting the sound between the ground and the inversion layer.<ref>{{cite web|title=How fog can play tricks on your ears?|url=http://www.katu.com/blogs/weather/34619514.html|work=katu.com|url-status=live|archive-url=https://web.archive.org/web/20150412212345/http://www.katu.com/blogs/weather/34619514.html|archive-date=12 April 2015}}</ref>