Fine Fuel Moisture 4 : The probable moisture content of fast-drying fuels which have a time lag constant of one hour or less; such as, grass, leaves, ferns, tree moss, draped needles, and small twigs
US Forest Service, Glossary of Fire Behavior & Fire Weather Terms, Washington, D.C., USA 2010. http://www.erh.noaa.gov/phi/fire_glossary.htm, (For Fr - Amer) {505}
