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The Forest fire weather index (FWI) (French: indice forêt météo, IFM) is an estimation of the risk of wildfire computed by Météo France and the Meteorological Service of Canada. It was introduced in France in 1992 but is based on a Canadian empirical model developed and widely used since 1976.〔 〕 == Description == The index is a whole number that ranges between 0 and 20 in France and up to above 30 in Canada. It is computed from five components. The first three components are numeric ratings of the moisture content of litter and other fine fuels, the average moisture content of loosely compacted organic layers of moderate depth, and the average moisture content of deep, compact organic layers. The last two components are the rate of fire spread if fuel is available for combustion, and the frontal fire intensity. The essential informations needed to calculate this index are : * the humidity of the air at the beginning of the afternoon (when it has its lowest value); * the temperature in the middle of the afternoon (when it has its highest value); * the precipitations during 24h (from noon to noon) ; * the maximum speed of the average wind. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Forest fire weather index」の詳細全文を読む スポンサード リンク
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