龍(long)卷風是(shi)一種少見的局地性、小(xiao)尺度(du)、突發性的強對(dui)流(liu)天(tian)氣(qi),是(shi)在強烈的不穩定的天(tian)氣(qi)狀況下由空氣(qi)對(dui)流(liu)運動(dong)造成的、強烈的、小(xiao)范圍的空氣(qi)渦(wo)旋。
從積雨云中(zhong)伸下(xia)的(de)(de)(de)(de)(de)猛(meng)烈旋轉的(de)(de)(de)(de)(de)漏斗(dou)狀(zhuang)云樓。它有(you)(you)(you)時(shi)(shi)稍伸即隱,有(you)(you)(you)時(shi)(shi)懸掛空中(zhong)或觸(chu)及(ji)地(di)面(mian)。龍(long)(long)卷(juan)風(feng)(feng)(feng)(feng)(feng)漏斗(dou)云的(de)(de)(de)(de)(de)軸一(yi)般(ban)(ban)垂直(zhi)于(yu)地(di)面(mian),在(zai)(zai)發展的(de)(de)(de)(de)(de)后期(qi),當上(shang)下(xia)層風(feng)(feng)(feng)(feng)(feng)速(su)(su)相差較大(da)時(shi)(shi),可成傾(qing)斜狀(zhuang)或彎曲狀(zhuang)。其下(xia)部直(zhi)徑最(zui)(zui)小(xiao)(xiao)的(de)(de)(de)(de)(de)只(zhi)有(you)(you)(you)幾(ji)米(mi),一(yi)般(ban)(ban)為(wei)數百米(mi),最(zui)(zui)大(da)可達千(qian)米(mi)以上(shang),上(shang)部直(zhi)徑一(yi)般(ban)(ban)為(wei)數千(qian)米(mi),最(zui)(zui)大(da)可達10公里(li)(li)。龍(long)(long)卷(juan)風(feng)(feng)(feng)(feng)(feng)的(de)(de)(de)(de)(de)尺度很(hen)小(xiao)(xiao),中(zhong)心氣(qi)壓(ya)(ya)很(hen)低(di),造(zao)成很(hen)大(da)的(de)(de)(de)(de)(de)水平(ping)氣(qi)壓(ya)(ya)梯度,從而(er)(er)導致(zhi)強(qiang)(qiang)烈的(de)(de)(de)(de)(de)風(feng)(feng)(feng)(feng)(feng)速(su)(su),中(zhong)心風(feng)(feng)(feng)(feng)(feng)速(su)(su)可達100-200米(mi)/秒。由于(yu)氣(qi)流(liu)的(de)(de)(de)(de)(de)旋轉力(li)很(hen)強(qiang)(qiang),常(chang)將(jiang)地(di)面(mian)的(de)(de)(de)(de)(de)水、塵(chen)土、泥沙挾卷(juan)而(er)(er)起(qi),其破壞力(li)變動(dong)范圍很(hen)大(da),弱者(zhe)僅(jin)能卷(juan)起(qi)稻草捆和(he)(或)衣物(wu)強(qiang)(qiang)者(zhe)可按樹倒屋,至把人、畜也(ye)一(yi)并(bing)升起(qi),經(jing)過(guo)水面(mian)時(shi)(shi)可吸(xi)水上(shang)升如柱,(這時(shi)(shi)稱水龍(long)(long)卷(juan)),所以龍(long)(long)卷(juan)風(feng)(feng)(feng)(feng)(feng)范圍雖小(xiao)(xiao),但(dan)造(zao)成的(de)(de)(de)(de)(de)災情(qing)卻(que)很(hen)嚴(yan)重。龍(long)(long)卷(juan)風(feng)(feng)(feng)(feng)(feng)的(de)(de)(de)(de)(de)移向、移速(su)(su)是(shi)由其母云(產(chan)生龍(long)(long)卷(juan)的(de)(de)(de)(de)(de)積雨云)的(de)(de)(de)(de)(de)移動(dong)決(jue)定(ding)的(de)(de)(de)(de)(de),母云的(de)(de)(de)(de)(de)移速(su)(su)通常(chang)為(wei)每小(xiao)(xiao)時(shi)(shi)40-50公里(li)(li),最(zui)(zui)快可達90-100公里(li)(li)。其移動(dong)路徑多呈直(zhi)線(xian),一(yi)般(ban)(ban)只(zhi)有(you)(you)(you)幾(ji)公里(li)(li),個別可達數十公里(li)(li)。龍(long)(long)卷(juan)風(feng)(feng)(feng)(feng)(feng)是(shi)強(qiang)(qiang)對流(liu)天氣(qi)的(de)(de)(de)(de)(de)產(chan)物(wu),常(chang)發生于(yu)北緯20-50度地(di)帶低(di)層大(da)氣(qi)層結具有(you)(you)(you)很(hen)大(da)對流(liu)不穩定(ding)的(de)(de)(de)(de)(de)地(di)區,往(wang)往(wang)與鋒面(mian)、氣(qi)旋或非熱帶性雷(lei)暴相伴隨。登陸(lu)后的(de)(de)(de)(de)(de)熱帶氣(qi)旋移到中(zhong)緯趨向衰亡時(shi)(shi),也(ye)很(hen)易出現龍(long)(long)卷(juan)風(feng)(feng)(feng)(feng)(feng),有(you)(you)(you)時(shi)(shi)還可出現在(zai)(zai)熱帶地(di)區。根據龍(long)(long)卷(juan)風(feng)(feng)(feng)(feng)(feng)產(chan)生的(de)(de)(de)(de)(de)地(di)區可分(fen)為(wei)陸(lu)龍(long)(long)卷(juan)(產(chan)生在(zai)(zai)陸(lu)地(di)上(shang)空)和(he)水龍(long)(long)卷(juan)(產(chan)生在(zai)(zai)海面(mian)或水面(mian)上(shang)空)。龍(long)(long)卷(juan)風(feng)(feng)(feng)(feng)(feng)很(hen)難預(yu)報,測雨雷(lei)達也(ye)未(wei)曾直(zhi)接觀測到過(guo)。
龍卷(juan)風(feng)(feng),是(shi)一(yi)(yi)種具有一(yi)(yi)定破壞力的(de)(de)自然(ran)現象(xiang)。一(yi)(yi)般情況下,龍卷(juan)風(feng)(feng)是(shi)一(yi)(yi)種氣旋。它在(zai)接(jie)觸地面時,直徑(jing)從幾(ji)(ji)米(mi)(mi)到(dao)幾(ji)(ji)百(bai)米(mi)(mi),平(ping)均為250米(mi)(mi)左右,最(zui)大(da)為1000米(mi)(mi)左右。在(zai)空中直徑(jing)可(ke)有幾(ji)(ji)千米(mi)(mi),最(zui)大(da)有10千米(mi)(mi)。極大(da)風(feng)(feng)速每小時可(ke)達150千米(mi)(mi)至450千米(mi)(mi),龍卷(juan)風(feng)(feng)持續時間,一(yi)(yi)般僅幾(ji)(ji)分鐘,最(zui)長不(bu)過(guo)幾(ji)(ji)小時。所到(dao)之處萬物遭劫。龍卷(juan)風(feng)(feng)漏斗狀中心由吸起的(de)(de)塵土(tu)和凝(ning)聚的(de)(de)水氣組成可(ke)見的(de)(de)“龍嘴”。在(zai)海洋上,尤(you)其是(shi)在(zai)熱帶,類似的(de)(de)景象(xiang)在(zai)發生(sheng)稱為海上龍卷(juan)風(feng)(feng)。
龍卷風(feng)通(tong)常是極(ji)其(qi)快速的(de),每秒(miao)鐘(zhong)100米(mi)(mi)的(de)風(feng)速不足為(wei)奇,甚至達(da)到每秒(miao)鐘(zhong)175米(mi)(mi)以(yi)上,比12級臺風(feng)還要大五、六倍。風(feng)的(de)范圍很小(xiao),一(yi)(yi)般(ban)直徑只有25~100米(mi)(mi),只在極(ji)少(shao)數的(de)情況下(xia)直徑才達(da)到一(yi)(yi)公里(li)以(yi)上;從(cong)發生到消失只有幾(ji)分(fen)種,最多幾(ji)個小(xiao)時。
大多數(shu)龍卷風在(zai)(zai)北半球是(shi)逆時(shi)針旋轉,在(zai)(zai)南半球是(shi)順時(shi)針,也有例外情況。卷風形成的確切機(ji)理仍在(zai)(zai)研究(jiu)中(zhong),一般認為是(shi)與大氣的劇烈活動有關。
從19世(shi)紀以來,天(tian)氣(qi)預(yu)報的準確性大(da)大(da)提高,氣(qi)象雷達能夠監測到龍卷風、颶(ju)風等各種災害風暴。
龍卷(juan)風經過(guo)之(zhi)處,常會發生(sheng)拔起(qi)大(da)樹、掀(xian)翻車(che)輛、摧(cui)毀(hui)建筑物等現象,它往(wang)往(wang)使(shi)成片莊稼、成萬株果木瞬間被毀(hui),令交通(tong)中斷,房屋倒塌,人畜(chu)生(sheng)命和經濟遭受損失。
龍卷風這(zhe)種自(zi)然現象是云層(ceng)中(zhong)(zhong)雷暴(bao)的產物,具體的說,龍卷風就(jiu)是雷暴(bao)巨大能量中(zhong)(zhong)的一小部分在很小的區(qu)域內集(ji)中(zhong)(zhong)釋放的一種形式。
龍卷(juan)風的形成可以分為四個階段:
(1)大氣的(de)(de)不穩定性(xing)產(chan)生強(qiang)(qiang)烈(lie)的(de)(de)上升氣流(liu),由于急流(liu)中(zhong)的(de)(de)最大過境(jing)氣流(liu)的(de)(de)影響(xiang),它被進一步加強(qiang)(qiang)。
(2)由于與在(zai)垂直方(fang)向上速(su)度(du)和方(fang)向均有切變的(de)風相互作用(yong),上升氣(qi)流在(zai)對流層(ceng)的(de)中部開(kai)始旋(xuan)(xuan)轉,形成中尺(chi)度(du)氣(qi)旋(xuan)(xuan)。
(3)隨著中尺度氣(qi)旋(xuan)向(xiang)地面(mian)發展和向(xiang)上伸展,它本身變細(xi)并增強。同時,一(yi)個(ge)小面(mian)積的增強輔合,即(ji)初生的龍(long)卷(juan)在氣(qi)旋(xuan)內部形成(cheng),產生氣(qi)旋(xuan)的同樣過(guo)程,形成(cheng)龍(long)卷(juan)核心。
(4)龍(long)卷(juan)核心中的旋轉與(yu)氣(qi)旋中的不同,它的強度(du)(du)足(zu)以使龍(long)卷(juan)一(yi)直伸展(zhan)到地(di)面(mian)。當發展(zhan)的渦旋到達地(di)面(mian)高(gao)度(du)(du)時(shi),地(di)面(mian)氣(qi)壓急(ji)劇下降,地(di)面(mian)風(feng)速急(ji)劇上升,形成龍(long)卷(juan)風(feng)。
龍(long)卷(juan)風(feng)(feng)發生至消散的(de)時(shi)間短(duan),作(zuo)用面積很(hen)小,以(yi)至于現有的(de)探測儀器(qi)沒有足夠的(de)靈敏(min)度來對(dui)龍(long)卷(juan)風(feng)(feng)進行準確的(de)觀測。相對(dui)來說,多(duo)普勒(le)雷(lei)達(da)是比較有效和常用的(de)一種(zhong)觀測儀器(qi)。多(duo)普勒(le)雷(lei)達(da)對(dui)準龍(long)卷(juan)風(feng)(feng)發出的(de)微(wei)波(bo)(bo)束,微(wei)波(bo)(bo)信號被(bei)龍(long)卷(juan)風(feng)(feng)中的(de)碎(sui)屑和雨點反(fan)(fan)射(she)后(hou)重被(bei)雷(lei)達(da)接(jie)(jie)收。如果龍(long)卷(juan)風(feng)(feng)遠離雷(lei)達(da)而去(qu),反(fan)(fan)射(she)回(hui)(hui)的(de)微(wei)波(bo)(bo)信號頻(pin)率將向低頻(pin)方(fang)向移(yi)(yi)(yi)動;反(fan)(fan)之(zhi),如果龍(long)卷(juan)風(feng)(feng)越來越接(jie)(jie)近雷(lei)達(da),則反(fan)(fan)射(she)回(hui)(hui)的(de)信號將向高頻(pin)方(fang)向移(yi)(yi)(yi)動。這種(zhong)現象被(bei)稱為多(duo)普勒(le)頻(pin)移(yi)(yi)(yi)。接(jie)(jie)收到(dao)信號后(hou),雷(lei)達(da)操作(zuo)人員就(jiu)可(ke)以(yi)通過分析頻(pin)移(yi)(yi)(yi)數據,計算出龍(long)卷(juan)風(feng)(feng)的(de)速度和移(yi)(yi)(yi)動方(fang)向。
雙(shuang)極化(hua)(hua)技術的出現對(dui)多普(pu)勒(le)(le)天氣(qi)雷(lei)達(da)(da)探測(ce)中氣(qi)旋和龍(long)卷(juan)進行(xing)了(le)有力的補充,全面提升了(le)對(dui)龍(long)卷(juan)微物(wu)理(li)特(te)征(zheng)分析與預警預報水平。①由于多普(pu)勒(le)(le)天氣(qi)雷(lei)達(da)(da)對(dui)較(jiao)小(xiao)尺度(du)的龍(long)卷(juan)渦旋探測(ce)需(xu)(xu)要(yao)具有良(liang)好的空(kong)間分辨率(lv),然而對(dui)雙(shuang)極化(hua)(hua)探測(ce)而言(yan)并(bing)(bing)不需(xu)(xu)要(yao)太高的精度(du)。②雙(shuang)極化(hua)(hua)特(te)征(zheng)信(xin)(xin)號(hao)不同于多普(pu)勒(le)(le)特(te)征(zheng)信(xin)(xin)號(hao),由于其是“各(ge)向同性(xing)”的,所以(yi)并(bing)(bing)不依賴(lai)于觀測(ce)角度(du)的變化(hua)(hua)。③當(dang)龍(long)卷(juan)在夜間發生或被(bei)大量降水包裹著難以(yi)通過(guo)多普(pu)勒(le)(le)雷(lei)達(da)(da)觀測(ce)發現時,雙(shuang)極化(hua)(hua)信(xin)(xin)息更能有效地將(jiang)其識別。
Wurman設計開發了第(di)一部(bu)X波段(duan)移動式快速(su)(su)掃(sao)描雷(lei)達(da)(da) Rapid DOW,該雷(lei)達(da)(da)每7秒可(ke)以完成一次360°的(de)(de)(de)體掃(sao),在(zai)14秒的(de)(de)(de)時間里可(ke)以探(tan)測(ce)到(dao) 12個波束范圍的(de)(de)(de)數(shu)據(ju),并且其距離分辨率達(da)(da)到(dao)11米,更(geng)易(yi)于對龍(long)卷(juan)三維結構進行研(yan)究。從當前對龍(long)卷(juan)的(de)(de)(de)探(tan)測(ce)技(ji)術(shu)來看(kan),快速(su)(su)掃(sao)描雷(lei)達(da)(da)在(zai)時空尺(chi)度上(shang)對龍(long)卷(juan)觀測(ce)獨特優勢。而美國計劃(hua)的(de)(de)(de)下一代天氣雷(lei)達(da)(da)網絡(luo)也定位為(wei)多功能相控陣雷(lei)達(da)(da)。所以可(ke)見該技(ji)術(shu)未(wei)來必將成為(wei)研(yan)究該類天氣的(de)(de)(de)主(zhu)要手(shou)段(duan)。
多(duo)漩渦(wo)龍(long)(long)卷風(Multiple vortex)指(zhi)帶(dai)有(you)兩股(gu)以上圍繞同一(yi)個中心旋轉的(de)(de)(de)漩渦(wo)的(de)(de)(de)龍(long)(long)卷風。多(duo)漩渦(wo)結構經(jing)常(chang)出現在劇烈的(de)(de)(de)龍(long)(long)卷風上,并且這些(xie)小漩渦(wo)在主(zhu)龍(long)(long)卷風經(jing)過的(de)(de)(de)地區上往往會造成更大的(de)(de)(de)破壞(huai)。
水(shui)(shui)龍(long)(long)(long)(long)卷(juan)(juan)(或稱(cheng)海龍(long)(long)(long)(long)卷(juan)(juan),英(ying)文:waterspout)可(ke)以簡(jian)單(dan)地定(ding)義為水(shui)(shui)上(shang)的龍(long)(long)(long)(long)卷(juan)(juan)風(feng),通(tong)常意思(si)是在(zai)水(shui)(shui)上(shang)的非超級單(dan)體(ti)龍(long)(long)(long)(long)卷(juan)(juan)風(feng)。世界各地的海洋和湖泊等都可(ke)能(neng)(neng)出現水(shui)(shui)龍(long)(long)(long)(long)卷(juan)(juan)。在(zai)美(mei)(mei)國(guo),水(shui)(shui)龍(long)(long)(long)(long)卷(juan)(juan)通(tong)常發(fa)生在(zai)美(mei)(mei)國(guo)東南部海岸(an)(an),尤(you)其在(zai)佛羅里達南部和墨(mo)西哥(ge)灣(wan)。水(shui)(shui)龍(long)(long)(long)(long)卷(juan)(juan)雖在(zai)定(ding)義上(shang)是龍(long)(long)(long)(long)卷(juan)(juan)風(feng)的一種,不(bu)過其破(po)壞性要比最(zui)強大的大草原龍(long)(long)(long)(long)卷(juan)(juan)風(feng)小(xiao),但是它們仍(reng)然是相當危(wei)險(xian)的。水(shui)(shui)龍(long)(long)(long)(long)卷(juan)(juan)能(neng)(neng)吹(chui)翻小(xiao)船,毀壞船只,當吹(chui)襲陸(lu)地時就有(you)更(geng)大的破(po)壞,并(bing)奪去(qu)生命。當水(shui)(shui)龍(long)(long)(long)(long)卷(juan)(juan)很可(ke)能(neng)(neng)產生或在(zai)海岸(an)(an)水(shui)(shui)域上(shang)已經(jing)看得見的時候(hou),美(mei)(mei)國(guo)國(guo)家氣象(xiang)局將會經(jing)常發(fa)出特殊的海上(shang)警告,或者當水(shui)(shui)龍(long)(long)(long)(long)卷(juan)(juan)會向陸(lu)地移動時發(fa)出龍(long)(long)(long)(long)卷(juan)(juan)風(feng)警告。
陸(lu)龍(long)卷(英文(wen):landspout,美國國家氣象局稱(cheng)dust-tube tornado)用以描述一種和(he)中尺度氣旋(xuan)沒有關聯的龍(long)卷風。陸(lu)龍(long)卷和(he)水(shui)龍(long)卷有一些相(xiang)同的特點(dian),例如強(qiang)度相(xiang)對較弱、持續時間短、冷凝形(xing)成的漏斗云較小且(qie)經常不接觸地(di)面(mian)等。雖然(ran)強(qiang)度相(xiang)對較弱,但陸(lu)龍(long)卷依然(ran)會帶來強(qiang)風和(he)嚴重破壞。
火(huo)龍(long)卷(juan),非(fei)常罕見的(de)龍(long)卷(juan)風(feng)形態,由陸龍(long)卷(juan)與火(huo)焰(yan)的(de)結(jie)合。2010年,位(wei)于(yu)南半球的(de)巴西遭遇罕見的(de)干旱(han)少(shao)雨天氣(qi),全國(guo)多(duo)地燃起了(le)(le)山火(huo)。8月24日,巴西圣保羅(luo)市一(yi)處(chu)火(huo)點(dian)刮(gua)起了(le)(le)龍(long)卷(juan)風(feng),形成了(le)(le)罕見的(de)火(huo)焰(yan)龍(long)卷(juan)風(feng)景觀(guan)。龍(long)卷(juan)風(feng)夾起火(huo)焰(yan)高達數米,像一(yi)條巨(ju)大(da)的(de)火(huo)龍(long)旋(xuan)轉前進(jin)。這條“火(huo)龍(long)風(feng)”于(yu)24日被(bei)拍攝到。“火(huo)龍(long)”在燃燒的(de)田(tian)野上飛(fei)舞高約數米高,阻斷(duan)了(le)(le)一(yi)條公路。為了(le)(le)熄滅(mie)這條“火(huo)龍(long)”,當(dang)地出動了(le)(le)直升(sheng)機。
出現(xian)“火(huo)龍(long)風”的(de)地區已經(jing)有3個月沒有下(xia)雨。異常干旱的(de)天氣(qi)和(he)強勁的(de)風勢助長了此處(chu)的(de)火(huo)勢。巴西(xi)全(quan)球(qiu)電視臺報(bao)道稱,圣保羅地區的(de)空氣(qi)干燥(zao)程度已趕(gan)上(shang)了撒(sa)哈拉沙(sha)漠。
龍卷(juan)風按它的破壞程度不同(tong),分(fen)為(wei)0-5增強藤田級(ji)數,簡(jian)單來說就稱為(wei)EF級(ji),由1971年芝加哥大學(xue)的藤田哲(zhe)也(ye)博士所提出(chu)。
EF0級(ji):風速在(zai)65-85英里(li)每小時,約合105-137公里(li)每小時,雖然較(jiao)弱,但還是足以把(ba)樹枝吹斷(duan),把(ba)較(jiao)輕的碎片卷起來擊(ji)碎玻璃,一些煙囪(cong)會(hui)被吹斷(duan)。(出(chu)現幾率極高(gao),53.5%)
EF1級(ji):風速在每(mei)小時(shi)86-110英里每(mei)小時(shi),約合138-177公里每(mei)小時(shi),它(ta)們可以把屋頂吹走,把活(huo)動板(ban)房給吹翻,一些(xie)較輕的汽(qi)車會(hui)被吹翻或刮離路面。(出現幾率較高,31.6%)
EF2級:風速在111-135英里每(mei)小時,約合(he)178-217公里每(mei)小時,它們可以把(ba)沉重的甘草包吹出(chu)去幾百米遠,把(ba)一(yi)棵大樹連根拔起,貨車可以刮離路面。(出(chu)現幾率中等偏(pian)低,10.7%)
EF3級:風(feng)速(su)在(zai)136-165英里每小(xiao)時,約合(he)218-266公里每小(xiao)時,它們可(ke)以把(ba)一(yi)(yi)輛較(jiao)重汽(qi)車吹翻(fan),樹木被(bei)吹離地面,房屋一(yi)(yi)大(da)半被(bei)毀,火(huo)車脫(tuo)離軌道(dao)。(出現幾率低,3.4%)
EF4級:風速在(zai)166-200英里每小(xiao)時(shi),約合267-322公里每小(xiao)時(shi),它(ta)們可以把一輛(liang)汽車刮(gua)飛(fei),把一幢牢固(gu)的房屋夷為(wei)平地,樹木被刮(gua)到幾百米高空。(出現幾率很低,0.7%)
EF5級(ji):EF5級(ji)風速超過(guo)每(mei)小時200英里每(mei)小時,也(ye)就是超過(guo)了322公里每(mei)小時,房屋完(wan)全(quan)吹毀,汽車(che)完(wan)全(quan)刮(gua)飛,路(lu)面上的(de)瀝青也(ye)會被(bei)刮(gua)走(zou),貨車(che)、火車(che)、列(lie)車(che)全(quan)部脫離地面。(出現(xian)幾率(lv)較低(di)偏高(gao),20%—45%)
龍(long)卷(juan)(juan)風并沒有EF6級(ji)。那是(shi)(shi)(shi)絕對不可能的,這是(shi)(shi)(shi)根據物理和(he)氣象(xiang)學(xue)推算(suan)出來的,所以,1999年5月3日俄克拉(la)荷(he)馬城的龍(long)卷(juan)(juan)風不是(shi)(shi)(shi)EF6級(ji),而是(shi)(shi)(shi)EF5級(ji),但是(shi)(shi)(shi)電視臺也(ye)報道過當天超過每小(xiao)時512公里(li)的風速,而且在一個雷(lei)達(da)上估測到了318英里(li)每小(xiao)時的大風,這就表明龍(long)卷(juan)(juan)風的破壞力量很大,不要相信有EF6級(ji)龍(long)卷(juan)(juan)風,那是(shi)(shi)(shi)虛構(gou)。
除此之外,龍卷風還可以分為4個形狀:
煙(yan)囪龍(long)卷(juan)風:輪廓直,比較粗壯,強(qiang)度中等,一般在EF2—EF4級左右。
繩形(xing)龍卷風:纖(xian)細,輪廓教(jiao)彎,強度弱,一般在EF0—EF2左右。
楔(xie)形(xing)龍卷風:長度較寬,可(ke)達1.5公里,寬度超過高度,強度強,一般在EF4—EF5左右。
雙(shuang)胞胎龍卷風:兩個龍卷風,有的粗(cu),有的細,強度不定。
全球除南極洲(zhou)以外的大(da)洲(zhou)都有龍(long)卷(juan)風記錄,龍(long)卷(juan)風主要(yao)發(fa)生(sheng)在中緯度地區,其(qi)(qi)中美國發(fa)生(sheng)最(zui)為頻繁,堪稱“龍(long)卷(juan)王國”,被稱為“龍(long)卷(juan)風之鄉”,其(qi)(qi)發(fa)生(sheng)的龍(long)卷(juan)風約占全球龍(long)卷(juan)風總數的75%;其(qi)(qi)次為加拿(na)大(da);歐洲(zhou)西(xi)部和中部、中國、孟(meng)加拉國、日本、澳大(da)利亞(ya)、新西(xi)蘭、南非和阿(a)根廷等國家(jia)或地區龍(long)卷(juan)風發(fa)生(sheng)也(ye)較為頻繁。
年(nian)(nian)(nian)(nian)尺度(du)特征美國龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)平(ping)均(jun)(jun)(jun)每(mei)年(nian)(nian)(nian)(nian)有(you)(you)1000多(duo)個(ge)(ge)(ge)(ge)(ge)(ge)(1991—2010年(nian)(nian)(nian)(nian)間,平(ping)均(jun)(jun)(jun)為1253個(ge)(ge)(ge)(ge)(ge)(ge)/年(nian)(nian)(nian)(nian))。其(qi)次為加拿大(da),記(ji)錄(lu)(lu)到(dao)(dao)的(de)(de)(de)(de)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)平(ping)均(jun)(jun)(jun)約(yue)70個(ge)(ge)(ge)(ge)(ge)(ge)/年(nian)(nian)(nian)(nian),估計實際發(fa)生(sheng)的(de)(de)(de)(de)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)平(ping)均(jun)(jun)(jun)約(yue)150個(ge)(ge)(ge)(ge)(ge)(ge)/年(nian)(nian)(nian)(nian)。歐(ou)洲(zhou)(zhou)平(ping)均(jun)(jun)(jun)觀測到(dao)(dao)的(de)(de)(de)(de)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)大(da)約(yue)有(you)(you)330個(ge)(ge)(ge)(ge)(ge)(ge)/年(nian)(nian)(nian)(nian),其(qi)中陸(lu)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)170個(ge)(ge)(ge)(ge)(ge)(ge),水(shui)(shui)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)160個(ge)(ge)(ge)(ge)(ge)(ge),而(er)實際發(fa)生(sheng)的(de)(de)(de)(de)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)大(da)約(yue)有(you)(you)700個(ge)(ge)(ge)(ge)(ge)(ge)/年(nian)(nian)(nian)(nian),其(qi)中陸(lu)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)300個(ge)(ge)(ge)(ge)(ge)(ge),水(shui)(shui)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)390個(ge)(ge)(ge)(ge)(ge)(ge)。歐(ou)洲(zhou)(zhou)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)多(duo)發(fa)生(sheng)于(yu)英國、德國、法(fa)國和(he)西(xi)(xi)(xi)班(ban)牙:英國(1981—2010年(nian)(nian)(nian)(nian)間)平(ping)均(jun)(jun)(jun)每(mei)年(nian)(nian)(nian)(nian)大(da)約(yue)有(you)(you) (47.2±10.5)個(ge)(ge)(ge)(ge)(ge)(ge)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng),其(qi)中陸(lu)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(36.5±10.1)個(ge)(ge)(ge)(ge)(ge)(ge),水(shui)(shui)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)(12.7±2.8)個(ge)(ge)(ge)(ge)(ge)(ge);法(fa)國平(ping)均(jun)(jun)(jun)每(mei)年(nian)(nian)(nian)(nian)有(you)(you)15~20個(ge)(ge)(ge)(ge)(ge)(ge)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)。亞洲(zhou)(zhou)的(de)(de)(de)(de)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)主要(yao)發(fa)生(sheng)在(zai)中國、日(ri)本、印度(du)和(he)孟加拉(la)國:中國平(ping)均(jun)(jun)(jun)每(mei)年(nian)(nian)(nian)(nian)發(fa)生(sheng)的(de)(de)(de)(de)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)有(you)(you)73個(ge)(ge)(ge)(ge)(ge)(ge);日(ri)本平(ping)均(jun)(jun)(jun)每(mei)年(nian)(nian)(nian)(nian)發(fa)生(sheng)20.5個(ge)(ge)(ge)(ge)(ge)(ge)陸(lu)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)和(he)4.5個(ge)(ge)(ge)(ge)(ge)(ge)水(shui)(shui)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan);孟加拉(la)國平(ping)均(jun)(jun)(jun)每(mei)年(nian)(nian)(nian)(nian)發(fa)生(sheng)的(de)(de)(de)(de)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)有(you)(you)2個(ge)(ge)(ge)(ge)(ge)(ge)。大(da)洋洲(zhou)(zhou)的(de)(de)(de)(de)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)主要(yao)發(fa)生(sheng)在(zai)澳(ao)大(da)利(li)亞和(he)新西(xi)(xi)(xi)蘭:澳(ao)大(da)利(li)亞平(ping)均(jun)(jun)(jun)每(mei)年(nian)(nian)(nian)(nian)發(fa)生(sheng)的(de)(de)(de)(de)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)有(you)(you)29個(ge)(ge)(ge)(ge)(ge)(ge),新西(xi)(xi)(xi)蘭平(ping)均(jun)(jun)(jun)每(mei)年(nian)(nian)(nian)(nian)發(fa)生(sheng)的(de)(de)(de)(de)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)有(you)(you)17個(ge)(ge)(ge)(ge)(ge)(ge)。南(nan)美洲(zhou)(zhou)的(de)(de)(de)(de)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)多(duo)發(fa)于(yu)阿根廷(ting)中部的(de)(de)(de)(de)潘帕斯草原:阿根廷(ting)平(ping)均(jun)(jun)(jun)每(mei)年(nian)(nian)(nian)(nian)記(ji)錄(lu)(lu)到(dao)(dao)的(de)(de)(de)(de)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)大(da)概有(you)(you)10個(ge)(ge)(ge)(ge)(ge)(ge);巴西(xi)(xi)(xi)、智利(li)和(he)烏拉(la)圭也有(you)(you)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)的(de)(de)(de)(de)記(ji)錄(lu)(lu),巴西(xi)(xi)(xi)平(ping)均(jun)(jun)(jun)每(mei)年(nian)(nian)(nian)(nian)記(ji)錄(lu)(lu)到(dao)(dao)的(de)(de)(de)(de)龍(long)(long)(long)(long)(long)(long)卷(juan)(juan)(juan)(juan)(juan)風(feng)有(you)(you)3個(ge)(ge)(ge)(ge)(ge)(ge)。
美國(guo)(guo)(guo)的(de)(de)(de)龍(long)(long)卷風(feng)(feng)(feng)多發(fa)(fa)(fa)(fa)(fa)(fa)(fa)于春(chun)季(ji),其(qi)(qi)次為(wei)夏(xia)(xia)(xia)(xia)季(ji),冬季(ji)最(zui)少發(fa)(fa)(fa)(fa)(fa)(fa)(fa)生(sheng)(sheng)。歐洲的(de)(de)(de)龍(long)(long)卷風(feng)(feng)(feng)主要(yao)發(fa)(fa)(fa)(fa)(fa)(fa)(fa)生(sheng)(sheng)在(zai)夏(xia)(xia)(xia)(xia)季(ji),其(qi)(qi)次為(wei)秋(qiu)季(ji):英(ying)國(guo)(guo)(guo)龍(long)(long)卷風(feng)(feng)(feng)主要(yao)發(fa)(fa)(fa)(fa)(fa)(fa)(fa)生(sheng)(sheng)在(zai)秋(qiu)季(ji)(9—11月(yue)),其(qi)(qi)次為(wei)夏(xia)(xia)(xia)(xia)季(ji)(6—8月(yue)),11月(yue)為(wei)龍(long)(long)卷風(feng)(feng)(feng)發(fa)(fa)(fa)(fa)(fa)(fa)(fa)生(sheng)(sheng)最(zui)多月(yue);德(de)國(guo)(guo)(guo)2/3的(de)(de)(de)龍(long)(long)卷風(feng)(feng)(feng)發(fa)(fa)(fa)(fa)(fa)(fa)(fa)生(sheng)(sheng)在(zai)6—8月(yue),其(qi)(qi)中7月(yue)龍(long)(long)卷風(feng)(feng)(feng)發(fa)(fa)(fa)(fa)(fa)(fa)(fa)生(sheng)(sheng)頻(pin)率達27%;法國(guo)(guo)(guo)的(de)(de)(de)龍(long)(long)卷風(feng)(feng)(feng)多發(fa)(fa)(fa)(fa)(fa)(fa)(fa)于春(chun)季(ji)和夏(xia)(xia)(xia)(xia)季(ji),8月(yue)發(fa)(fa)(fa)(fa)(fa)(fa)(fa)生(sheng)(sheng)最(zui)多;西班(ban)牙的(de)(de)(de)龍(long)(long)卷風(feng)(feng)(feng)多發(fa)(fa)(fa)(fa)(fa)(fa)(fa)于暖季(ji),明(ming)顯的(de)(de)(de)趨向于秋(qiu)季(ji)。澳(ao)大利亞的(de)(de)(de)龍(long)(long)卷風(feng)(feng)(feng)多發(fa)(fa)(fa)(fa)(fa)(fa)(fa)于初春(chun)和夏(xia)(xia)(xia)(xia)季(ji),其(qi)(qi)次為(wei)初冬。中國(guo)(guo)(guo)龍(long)(long)卷風(feng)(feng)(feng)發(fa)(fa)(fa)(fa)(fa)(fa)(fa)生(sheng)(sheng)的(de)(de)(de)季(ji)節變化特征明(ming)顯,主要(yao)集中在(zai)春(chun)夏(xia)(xia)(xia)(xia)兩季(ji),尤以7月(yue)和8月(yue)最(zui)多,兩月(yue)約占全年總數的(de)(de)(de)50%以上。日本56%的(de)(de)(de)陸龍(long)(long)卷發(fa)(fa)(fa)(fa)(fa)(fa)(fa)生(sheng)(sheng)在(zai)7—10月(yue),其(qi)(qi)中9月(yue)最(zui)為(wei)頻(pin)繁,3月(yue)最(zui)少;水龍(long)(long)卷主要(yao)發(fa)(fa)(fa)(fa)(fa)(fa)(fa)生(sheng)(sheng)在(zai)9—10月(yue),10月(yue)最(zui)多。
美(mei)國(guo)(guo)的(de)(de)(de)(de)(de)(de)佛羅里達州(zhou)和(he)(he)(he)(he)(he)中(zhong)(zhong)南(nan)部(bu)(bu)(bu)平(ping)(ping)(ping)(ping)原(yuan)(yuan)是(shi)龍(long)(long)(long)(long)卷(juan)(juan)(juan)風(feng)(feng)的(de)(de)(de)(de)(de)(de)高發(fa)(fa)區(qu),中(zhong)(zhong)南(nan)部(bu)(bu)(bu)平(ping)(ping)(ping)(ping)原(yuan)(yuan)稱為“龍(long)(long)(long)(long)卷(juan)(juan)(juan)走廊”,其范圍一般指從(cong)德(de)克(ke)薩斯(si)州(zhou)中(zhong)(zhong)部(bu)(bu)(bu)向北(bei)到(dao)(dao)愛荷華州(zhou)北(bei)部(bu)(bu)(bu),以及從(cong)堪薩斯(si)州(zhou)中(zhong)(zhong)部(bu)(bu)(bu)和(he)(he)(he)(he)(he)內布(bu)拉(la)斯(si)加東(dong)(dong)部(bu)(bu)(bu)到(dao)(dao)俄亥俄西(xi)(xi)部(bu)(bu)(bu)的(de)(de)(de)(de)(de)(de)區(qu)域。英國(guo)(guo)的(de)(de)(de)(de)(de)(de)龍(long)(long)(long)(long)卷(juan)(juan)(juan)主(zhu)(zhu)要發(fa)(fa)生于(yu)英格蘭的(de)(de)(de)(de)(de)(de)東(dong)(dong)部(bu)(bu)(bu)和(he)(he)(he)(he)(he)南(nan)部(bu)(bu)(bu)以及海峽群島周(zhou)邊。德(de)國(guo)(guo)的(de)(de)(de)(de)(de)(de)龍(long)(long)(long)(long)卷(juan)(juan)(juan)風(feng)(feng)多(duo)發(fa)(fa)于(yu)沿海和(he)(he)(he)(he)(he)丘陵地(di)區(qu)。法國(guo)(guo)的(de)(de)(de)(de)(de)(de)龍(long)(long)(long)(long)卷(juan)(juan)(juan)風(feng)(feng)多(duo)發(fa)(fa)于(yu)西(xi)(xi)北(bei)部(bu)(bu)(bu)、南(nan)部(bu)(bu)(bu)和(he)(he)(he)(he)(he)東(dong)(dong)部(bu)(bu)(bu)。西(xi)(xi)班牙的(de)(de)(de)(de)(de)(de)龍(long)(long)(long)(long)卷(juan)(juan)(juan)風(feng)(feng)多(duo)發(fa)(fa)于(yu)地(di)中(zhong)(zhong)海區(qu)域和(he)(he)(he)(he)(he)加的(de)(de)(de)(de)(de)(de)斯(si)灣附近省(sheng)(sheng)(sheng)份(fen)。中(zhong)(zhong)國(guo)(guo)龍(long)(long)(long)(long)卷(juan)(juan)(juan)風(feng)(feng)一般多(duo)發(fa)(fa)生在中(zhong)(zhong)東(dong)(dong)部(bu)(bu)(bu)地(di)形相對平(ping)(ping)(ping)(ping)坦(tan)的(de)(de)(de)(de)(de)(de)平(ping)(ping)(ping)(ping)原(yuan)(yuan)地(di)區(qu),平(ping)(ping)(ping)(ping)原(yuan)(yuan)多(duo)于(yu)山區(qu);從(cong)區(qu)域尺(chi)度(du)來(lai)看(kan),長(chang)江三角洲(zhou)、蘇北(bei)、魯西(xi)(xi)南(nan)、豫東(dong)(dong)等(deng)(deng)平(ping)(ping)(ping)(ping)原(yuan)(yuan)、湖沼區(qu)以及雷州(zhou)半島等(deng)(deng)地(di)都(dou)是(shi)龍(long)(long)(long)(long)卷(juan)(juan)(juan)風(feng)(feng)的(de)(de)(de)(de)(de)(de)易發(fa)(fa)區(qu);從(cong)省(sheng)(sheng)(sheng)級行(xing)政單元尺(chi)度(du)來(lai)看(kan),江蘇省(sheng)(sheng)(sheng)、安徽(hui)省(sheng)(sheng)(sheng)、廣(guang)東(dong)(dong)省(sheng)(sheng)(sheng)、河南(nan)省(sheng)(sheng)(sheng)、湖北(bei)省(sheng)(sheng)(sheng)是(shi)龍(long)(long)(long)(long)卷(juan)(juan)(juan)風(feng)(feng)多(duo)發(fa)(fa)的(de)(de)(de)(de)(de)(de)省(sheng)(sheng)(sheng)份(fen),黑龍(long)(long)(long)(long)江省(sheng)(sheng)(sheng)、河北(bei)省(sheng)(sheng)(sheng)、浙江省(sheng)(sheng)(sheng)、江西(xi)(xi)省(sheng)(sheng)(sheng)和(he)(he)(he)(he)(he)湖南(nan)省(sheng)(sheng)(sheng)等(deng)(deng)省(sheng)(sheng)(sheng)份(fen)龍(long)(long)(long)(long)卷(juan)(juan)(juan)風(feng)(feng)的(de)(de)(de)(de)(de)(de)發(fa)(fa)生頻次較高。1961—1993年(nian)間日本的(de)(de)(de)(de)(de)(de)陸(lu)龍(long)(long)(long)(long)卷(juan)(juan)(juan)和(he)(he)(he)(he)(he)水龍(long)(long)(long)(long)卷(juan)(juan)(juan)主(zhu)(zhu)要發(fa)(fa)生在沿海地(di)區(qu),而(er)關東(dong)(dong)地(di)區(qu)大量龍(long)(long)(long)(long)卷(juan)(juan)(juan)風(feng)(feng)遠離沿海區(qu)域。大洋洲(zhou)的(de)(de)(de)(de)(de)(de)龍(long)(long)(long)(long)卷(juan)(juan)(juan)風(feng)(feng)主(zhu)(zhu)要發(fa)(fa)生在澳(ao)(ao)大利(li)亞(ya)和(he)(he)(he)(he)(he)新西(xi)(xi)蘭。澳(ao)(ao)大利(li)亞(ya)的(de)(de)(de)(de)(de)(de)龍(long)(long)(long)(long)卷(juan)(juan)(juan)風(feng)(feng)主(zhu)(zhu)要發(fa)(fa)生于(yu)東(dong)(dong)南(nan)部(bu)(bu)(bu)和(he)(he)(he)(he)(he)西(xi)(xi)南(nan)部(bu)(bu)(bu)。南(nan)美(mei)洲(zhou)的(de)(de)(de)(de)(de)(de)龍(long)(long)(long)(long)卷(juan)(juan)(juan)風(feng)(feng)多(duo)發(fa)(fa)于(yu)阿根廷中(zhong)(zhong)部(bu)(bu)(bu)的(de)(de)(de)(de)(de)(de)潘帕(pa)斯(si)草原(yuan)(yuan)。巴西(xi)(xi)龍(long)(long)(long)(long)卷(juan)(juan)(juan)多(duo)發(fa)(fa)于(yu)南(nan)部(bu)(bu)(bu)和(he)(he)(he)(he)(he)東(dong)(dong)南(nan)部(bu)(bu)(bu)。
我(wo)國(guo)大部分(fen)省(區、市)都(dou)有龍卷(juan)風(feng)的(de)蹤跡(ji),主要發生在我(wo)國(guo)東部平原地區,1991年(nian)(nian)-2014年(nian)(nian),我(wo)國(guo)平均每年(nian)(nian)有43個(ge)龍卷(juan)風(feng),其中江(jiang)蘇和廣東最多,年(nian)(nian)均龍卷(juan)風(feng)分(fen)別(bie)為5.5個(ge)和4.8個(ge)。春季、夏(xia)季是龍卷(juan)風(feng)的(de)多發季節,4-8月龍卷(juan)風(feng)占全年(nian)(nian)的(de)92%。
龍(long)卷風(feng)是(shi)一種(zhong)破壞力極強的小(xiao)尺度天(tian)氣(qi)(qi)現象(xiang),直徑一般在(zai)100米以下,強龍(long)卷可達幾百米到(dao)1千米左(zuo)右。相(xiang)比于(yu)臺風(feng)、副高這些(xie)天(tian)氣(qi)(qi)系統中的“大(da)塊頭(tou)”,龍(long)卷風(feng)絕對屬于(yu)“小(xiao)個子”。而當前(qian)我們的氣(qi)(qi)象(xiang)臺站(zhan)不夠密集,以至于(yu)龍(long)卷風(feng)經常躲過氣(qi)(qi)象(xiang)監測(ce)的“法眼”。
龍卷風強對(dui)流(liu)(liu)天氣(qi)往往生成很(hen)突(tu)然,對(dui)某一(yi)地(di)區的影(ying)響時(shi)間也相對(dui)較短,“生命史”只有(you)十幾分鐘到個把小(xiao)時(shi)。因此(ci),要提前24小(xiao)時(shi)或(huo)是48小(xiao)時(shi)預報(bao)局部地(di)區的強對(dui)流(liu)(liu)天氣(qi)也就非常困難了。
龍卷風等強對流天氣的(de)生成和發展需要衡量綜合大氣條件(jian),而這(zhe)些條件(jian)往(wang)往(wang)是難以預料、不確(que)切的(de),再(zai)加上不同(tong)地區之間各(ge)不相(xiang)同(tong)的(de)地形(xing)因素(su),也進一步增加了準確(que)監測、預報的(de)難度(du)。
(1)龍卷(juan)風(feng)發(fa)生是(shi)和強(qiang)烈(lie)發(fa)展的(de)積雨(yu)(yu)云(yun)聯(lian)系在一(yi)起(qi)的(de),也(ye)就是(shi)通常所(suo)說的(de)雷雨(yu)(yu)云(yun)。龍卷(juan)風(feng)出現時天空往(wang)往(wang)烏天黑地(di)(云(yun)層(ceng)低(di)而深(shen)厚、亮度差(cha))、電閃雷鳴(ming)、風(feng)雨(yu)(yu)交加。以春未到(dao)秋初最常見,在一(yi)天中以下(xia)(xia)午至傍晚和凌(ling)晨(chen)至早晨(chen)出現最多。當看到(dao)天空有類似的(de)癥兆就要引起(qi)注意。人群應立(li)刻(ke)離(li)開危險房屋、活(huo)動場(chang)(chang)所(suo)或(huo)其他簡易(yi)臨時住處,到(dao)附近比較堅固(gu)的(de)房屋內躲(duo)避(bi)。在公共(gong)場(chang)(chang)所(suo),要服從指揮,有秩序地(di)向(xiang)指定(ding)地(di)點疏散。躲(duo)避(bi)龍卷(juan)風(feng)最為安全的(de)地(di)方是(shi)位于地(di)下(xia)(xia)的(de)空間或(huo)場(chang)(chang)所(suo)(如地(di)下(xia)(xia)室或(huo)半地(di)下(xia)(xia)室),地(di)面上所(suo)有建筑物此時都不(bu)是(shi)安全躲(duo)避(bi)的(de)場(chang)(chang)所(suo)。
(2)在野外遇到龍(long)卷(juan)風(feng)襲擊時,不必驚(jing)慌失(shi)措,應迅速朝龍(long)卷(juan)風(feng)移動方向的垂直方向跑動,伏(fu)于低(di)洼地(di)面、溝渠等,但要遠離(li)大樹、電線桿、廣告(gao)牌(pai)、圍墻等,以(yi)免被(bei)(bei)砸、被(bei)(bei)壓或發生觸電事故。如在汽(qi)(qi)車(che)(che)中,應及時離(li)開(kai),到低(di)洼地(di)躲避,因為汽(qi)(qi)車(che)(che)本身沒有防御龍(long)卷(juan)風(feng)能力,一(yi)旦汽(qi)(qi)車(che)(che)和人同時被(bei)(bei)龍(long)卷(juan)風(feng)卷(juan)起,危害更(geng)大。
(3)在家(jia)遇(yu)到龍卷風時,遠(yuan)離和龍卷風同方(fang)向的(de)窗、門、房屋(wu)的(de)外圍(wei)墻壁(bi),盡可能在龍卷風相反方(fang)向角(jiao)落或比(bi)較(jiao)(jiao)堅固的(de)小房間抱頭(tou)蹲(dun)下,保護好自己的(de)頭(tou)部。在樓(lou)上,特別是農村的(de)樓(lou)房內,應立即(ji)暫(zan)避到一樓(lou)比(bi)較(jiao)(jiao)堅固的(de)桌子底下或廁所(suo)、儲(chu)物間內。這是因(yin)為龍卷風中心的(de)氣壓極低,容(rong)易被龍卷風外吸、房屋(wu)倒塌而殃(yang)及室(shi)內人員安全。
(4)在遭遇龍(long)卷風和(he)發生房屋(wu)倒塌、電(dian)桿折斷的(de)情況(kuang)下(xia),應(ying)及(ji)時切斷電(dian)源,以防(fang)觸電(dian)和(he)引(yin)發火災事故(gu)。如(ru)果是化工生產企業遭受龍(long)卷風襲(xi)擊(ji),應(ying)及(ji)時關閉有(you)毒化學物品閥門(men),控制(zhi)化學物品泄漏,防(fang)止污染源向土壤(rang)和(he)水面擴散(san),必要時組織附(fu)近市(村)民緊急轉移(yi)。
(5)龍卷(juan)(juan)風(feng)(feng)(feng)后自救(jiu)(jiu)互救(jiu)(jiu)。由于(yu)龍卷(juan)(juan)風(feng)(feng)(feng)的(de)風(feng)(feng)(feng)力(li)特別大(da),具(ju)有(you)巨大(da)的(de)破(po)壞作(zuo)用(yong),龍卷(juan)(juan)經(jing)過的(de)區域(yu)內(nei),房屋(wu)等(deng)建筑物常會(hui)遭(zao)受不(bu)(bu)同(tong)程度的(de)破(po)壞,甚至發生(sheng)倒塌(ta)。因(yin)此,受龍卷(juan)(juan)影(ying)響地區的(de)群(qun)眾,尤其(qi)是家庭、鄰里之間在(zai)災后第一時(shi)(shi)間的(de)自救(jiu)(jiu)互救(jiu)(jiu)可最(zui)大(da)限(xian)度減(jian)少(shao)人員(yuan)傷亡(wang)。被(bei)埋(mai)壓(ya)人員(yuan)要(yao)保(bao)持(chi)清醒頭(tou)腦,盡快想法脫(tuo)離險(xian)境,如果不(bu)(bu)能自我(wo)脫(tuo)險(xian)時(shi)(shi),應(ying)盡量創(chuang)造和擴大(da)安全(quan)生(sheng)存空間,減(jian)少(shao)對(dui)身體的(de)擠壓(ya),特別是對(dui)腹部以(yi)上身體部位(wei)的(de)壓(ya)物要(yao)清除或(huo)移開,加強對(dui)頭(tou)部及口、鼻等(deng)器(qi)官(guan)的(de)自我(wo)保(bao)護,等(deng)待救(jiu)(jiu)援。救(jiu)(jiu)援時(shi)(shi)要(yao)講究方法,首先(xian)應(ying)使被(bei)救(jiu)(jiu)者暴露頭(tou)部,保(bao)持(chi)呼(hu)吸(xi)暢(chang)通,如有(you)窒息,應(ying)立即進行人工呼(hu)吸(xi)。其(qi)次不(bu)(bu)可生(sheng)拉硬(ying)扯或(huo)使用(yong)利器(qi)硬(ying)挖被(bei)埋(mai)者,以(yi)免造成進一步的(de)損傷,同(tong)時(shi)(shi)對(dui)傷重者及時(shi)(shi)送(song)醫院搶救(jiu)(jiu)。