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Quad-State Tornado May Be Longest-Lasting Ever
四个州的龙卷风可能是有史以来持续时间最长的
The monster tornado that destroyed the town of Mayfield, Ky., during last weekend’s deadly outbreak in the Midwest and Southeast may have traversed four states without ever lifting off the ground. The National Weather Service (NWS) office in Paducah, Ky., confirmed to the Weather Channel this week that the “Quad-State Tornado” carved a continuous path of 128 miles through the office’s region of responsibility (which covers southeastern Missouri, western Kentucky, southern Illinois and the southernmost tip of Indiana) last Friday.
巨大的龙卷风摧毁了肯塔基州的梅菲尔德镇。上周末在美国中西部和东南部爆发的致命龙卷风可能已经穿越了四个州，从未离开地面。本周，位于肯塔基州帕迪尤卡的美国国家气象局办公室向天气频道证实，上周五，“席卷了四州的龙卷风”在该办公室负责的地区（包括密苏里州东南部、肯塔基州西部、伊利诺伊州南部和印第安纳州最南端）刮出了一条长达128英里的连续路径。
Offices with bordering jurisdictions are analyzing whether the tornado went on to cover a total of 250 miles across Arkansas, Missouri, Tennessee and Kentucky. If it did so, it would break a record set on March 18, 1925, when the Tri-State Tornado ripped across 219 miles of Missouri, Illinois and Indiana. From touchdown to dissipation, the Quad-State Tornado may have spent a stunning four hours on the ground. Most tornadoes survive for no more than 10 to 20 minutes, says John Allen, a meteorologist and climate scientist at Central Michigan University.
相邻辖区的办公室正在分析龙卷风是否继续在阿肯色州、密苏里州、田纳西州和肯塔基州蔓延了250英里。如果确实是这样，它将打破1925年3月18日创下的记录，当时席卷三州的龙卷风席卷了密苏里州、伊利诺伊州和印第安纳州219英里。从着陆到消散，席卷了四州的龙卷风可能在地面上度过了令人震惊的四个小时。中密歇根大学的气象学家和气候科学家约翰·艾伦说，大多数龙卷风的持续时间不超过10到20分钟。
The recent twister was able to last so long because a number of crucial ingredients came together. The recipe for such a record-breaker starts with the right atmospheric conditions to create a supercell thunderstorm, the strongest of all thunderstorm types. Supercell storms also require wind shear - winds blowing from different directions at different heights in the atmosphere - in order to form.
最近的龙卷风之所以能够持续这么久，是因为许多关键的成分都聚集在一起。这样一个打破记录的方法从正确的大气条件开始，创造出超级单体雷暴，超级单体雷暴是所有雷暴类型中最强的。超级单体雷暴还需要风切变——从大气中不同高度、不同方向吹来的风——才能形成。
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