[{"data":1,"prerenderedAt":72},["ShallowReactive",2],{"q-fire-111-1-fire-science-003":3},{"subject":4,"subjectSlug":5,"subjectKicker":6,"subjectShort":7,"question":8,"related":27,"sameNumber":52,"hasEssay":26},"火災學概要","fire-science","火災學 · Fire Science","火災學",{"id":9,"webId":10,"year":11,"session":12,"subject":4,"number":13,"stem":14,"options":15,"answer":20,"answerNote":21,"images":22,"imagesPending":23,"lawTimestamp":11,"explanation":24,"explanationDeep":25,"freq":12,"indexable":26},"fire-111-1-火災學概要-003","fire-111-1-fire-science-003",111,1,3,"實效濕度低於多少時，日本即發布火災警報？",{"A":16,"B":17,"C":18,"D":19},"90%","80%","70%","60%","D",null,[],false,"本題考點：實效濕度的意義，以及日本發布火災警報所採用的門檻數值。\n【正解理由】實效濕度是把當日與前數日的相對濕度依遞減係數加權平均後所得的指標，用來代表木材等纖維質可燃物實際的乾燥程度。日本的火災氣象通報與火災警報，長期以實效濕度降至 60% 以下作為主要發布指標，並常併同最小相對濕度 40% 以下、風速每秒 7 公尺以上一併判斷。四個選項中符合此門檻者為 60%，故選 D。\n【逐項排除】\n(A) 錯誤。90% 屬相當潮濕的狀態，可燃物含水率高、著火所需熱量大，若以此為門檻幾乎終年都要發布警報，不具警示功能。\n(B) 錯誤。80% 同樣偏濕，未達使木材等可燃物明顯乾燥的程度，不是火災警報所採門檻。\n(C) 錯誤。70% 已接近乾燥，但仍高於日本採用的發布值，是本題最容易被誤選的混淆數值。\n(D) 正確。實效濕度低於 60% 表示連日乾燥、可燃物含水率下降，延燒危險顯著升高，即為發布火災警報的指標。\n【記憶點】「六四七」：實效濕度 60%、最小濕度 40%、風速每秒 7 公尺。","實效濕度並非當日的相對濕度，而是把最近數日的濕度依時間遞減加權後求得的乾燥指標。常見表示式為 He＝(1－r)(H0＋rH1＋r²H2＋r³H3＋…)，其中 H0 為當日平均相對濕度、H1、H2 依序為前一日、前二日的平均相對濕度，r 為遞減係數，一般取 0.7。取 0.7 的意義是「昨日的乾燥狀況對今日的可燃物仍留有約七成影響」，因此連續數日晴朗乾燥之後，即使當天下了一場小雨，實效濕度仍可能維持在低檔，這正是它比單日相對濕度更能反映火災危險的原因。\n日本的火災警報以三個數字為指標：實效濕度 60% 以下、最小相對濕度 40% 以下、風速每秒 7 公尺以上，各地方政府得依地區特性微調。這組數字源自統計上大火頻發的氣象條件——乾燥使可燃物含水率下降、著火所需熱量減少，強風則加速延燒並造成飛火，兩者同時出現時延燒危險最高。日本歷史上多次都市大火（如新潟、酒田大火）皆發生在乾燥強風的季節，是這套指標的實證背景。\n易混淆概念對照：含水率是可燃物本身的水分比例，相對濕度是當下空氣的水汽飽和程度，實效濕度則是加權過去數日的空氣濕度。三者層次不同，門檻數值不可互換，選擇題常把「實效濕度 60%」與「最小濕度 40%」對調來設陷阱。\n延伸考點：木材含水率愈低，著火時間愈短、火焰傳播速度愈快；風速愈大，延燒方向的火勢擴大速率愈高，且飛火距離增加。台灣則以乾燥特報與東北季風、焚風時期的火災統計為對應命題素材。",true,[28,32,36,39,43,48],{"webId":29,"stem":30,"number":31,"year":11,"session":12},"fire-111-1-fire-science-002","有關爆燃與爆轟，下列敘述何者錯誤？",2,{"webId":33,"stem":34,"number":35,"year":11,"session":12},"fire-111-1-fire-science-004","日本東京放映所及精神病診所火災起因為縱火，請問汽油在空氣中的燃燒下限為何？",4,{"webId":37,"stem":38,"number":12,"year":11,"session":12},"fire-111-1-fire-science-001","近年來已有水滅火器經型式認可，下列敘述何者正確？",{"webId":40,"stem":41,"number":42,"year":11,"session":12},"fire-111-1-fire-science-005","在苯中置入油酸鎂等金屬鹼，係採取下列何種防止靜電發生的方法？",5,{"webId":44,"stem":45,"number":46,"year":47,"session":12},"fire-110-1-fire-science-040","常見吸入火場中的煙霧而中毒者，其最主要之原因即為吸入太多的一氧化碳（CO），一氧化碳往往是火場的致命殺手，其濃度達多少時可以讓人在 1 分鐘內死亡？",40,110,{"webId":49,"stem":50,"number":51,"year":11,"session":12},"fire-111-1-fire-science-006","火災成長歷程中，下列何者非閃燃之現象？",6,[53,57,61,65,68],{"webId":54,"year":55,"stem":56,"number":13},"fire-114-1-fire-science-003",114,"下列有關儲槽火災之敘述何者錯誤？",{"webId":58,"year":59,"stem":60,"number":13},"fire-113-1-fire-science-003",113,"當起火區域產生閃燃時，人在其中是無法存活的，對於閃燃現象之敘述，下列何者錯誤？",{"webId":62,"year":63,"stem":64,"number":13},"fire-112-1-fire-science-003",112,"下列何者非為火災之特性？",{"webId":66,"year":47,"stem":67,"number":13},"fire-110-1-fire-science-003","依據建築物火災的特性，當進入「穩態燃燒」階段時，釋熱率（Q）與時間（t）的關係為何？",{"webId":69,"year":70,"stem":71,"number":13},"fire-109-1-fire-science-003",109,"依用戶用電設備設置規則及建築技術規則，下列避雷設置敘述何者錯誤？",1785129966693]