浅谈龙卷风的形成与危害.doc

浅谈龙卷风的形成与危害 摘要：龙卷风是一种自然界存在的天气现象，具有很强的破坏力，在世界上很多国家均有发生，古往今来，给人们留下了无数悲伤和恐惧的记忆。对龙卷风这种天气现象以及它对地球上大范围地区的巨大影响所做读者可以从中了解龙卷风形成所需的条件并做好预防。涵盖了以下方面的信息：Tornado’s conformation、harm、prediction and self– measure brief analysis Abstract: tornado, a natural weather phenomenon, often makes great damages to people’s life, both economically and physically, with its huge destructiveness, especially in America. At present, the scientific and technological level is far less to exactly forecast all information about a tornado and to protect people from its invasion. By deepening the understand of tornadoes, we can effectively forecast and prevent tornadoes, to some degree, lessen damages and provide assistance to help people survive it. Therefore, the research of tornadoes is of great significance. In principle of scientific, practical, simple and understandable, this thesis introduces the characteristics, forming conditions, forming mechanism, motive power of a tornado, and its development, damage, and signs before it comes, as well as how to prevent it, mish its negative effects, and how to have self-aid or mutual aid when a tornado comes. The paper accurately introduces basic information about tornadoes and focus on how a tornado grows and makes damage, and some self-help measures, to make people known more about tornadoes and learn how to escape from a tornado disaster. Key words: tornado; form; damage; forecast; self-help measure目录 1 认识龙卷风 1 1.1 什么是龙卷风 1 1.1.1定义 1 1.1.2概述 1 1.2龙卷风的特点 2 1.2.1袭击范围小 2 1.2.2寿命短促 2 1.2.3出现的随机性大 2 1.2.4中心气压极低 2 1.2.5风力巨大，破坏力极强 3 1.2.6蕴含能量巨大 3 1.3 龙卷风的分类 3 1.3.1按发生位置分类 3 1.3.2按强度分类 4 1.3.3按形状分类 4 1.3.4按龙卷风发生时的形态分类 4 1.3.5其他形式分类 5 1.3.6类似龙卷风的现象 5 1.4龙卷的等级划分及强度判断 6 1.4.1龙卷风的分级 6 1.4.2龙卷风强度判断 6 2 龙卷风的形成 7 2.1龙卷风产生的条件 7 2.2龙卷风的动力源 7 2.2.1引言 7 2.2.2旋转气流加强实验 8 2.2.3水蒸气凝结抽空实验 9 2.2.4总结 10 2.3龙卷风的形成机制 11 2.3.1龙卷风的角动量 11 2.3.2最小半径rmin圆柱内低气压的形成 13 2.4龙卷风的形成过程 14 2.4.1龙卷风的形成 14 2.4.2龙卷风的形成过程归纳 15 2.5龙卷风的结构 15 2.5.1龙卷风的漏斗为何向下延伸，又怎么为人眼所见 16 2.5.2尘埃和碎屑 16 2.5.3抽吸性涡旋 17