Forces of Nature: ThinkQuest 2000 (Team #C003603)
http://library.thinkquest.org/C003603/english/fogandmist/preparation.shtml
Although fog is not a terribly great threat, man has still come up with ingenious devices to help lessen its danger. For example, radio beacons and markers have been developed, especially for aircraft and sea-going vessels, which allows them to travel even in foggy weather.