Conditions for the occurrence of severe local storms
Conditions for the occurrence of severe local storms
复制标题
局地强风暴的发生条件
DOI：
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发表时间：
1968
期刊：
影响因子：
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通讯作者：
F. Ludlam
中科院分区：
文献类型：
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作者：
T. Carlson;F. Ludlam
等熵面相对流分析技术用于研究与英格兰南部和美国中西部附近选定的严重局地风暴相关的大尺度（“天气”）情况（包括霍舍姆、沃金厄姆和加里风暴，其行为已在先前的几份出版物中描述过）。风暴发生在主要的低压槽前面，在汇合线附近（在西欧通常被认为是冷锋，而在美国则被认为是“干线”），在那里，随着高度的增加，风的增加有利于积雨云对流的组织和加强。当小规模对流被限制在位于广阔的干旱高原（西班牙或墨西哥）下风的非常温暖的空气羽流下最低1或2公里（导致异常高的湿球势温度）时，就会出现极端不稳定。当（反向的）低层气流最终到达高空抑制羽流的边缘时，这种不稳定性就被释放了。看来，严重的局部风暴的发生需要地理特征和大气流动模式的特别有利的结合。DOI: 10.1111 / j.2153-3490.1968.tb00364.x
The technique of relative-flow analysis on isentropic surfaces is used to examine the large- (“synoptic”-) scale situations associated with selected severe local storms near southern England and over the mid-western U.S.A. (including the Horsham, Wokingham, and Geary storms whose behaviour has been described in several previous publications). The storms occur ahead of major troughs, in the vicinity of confluence-lines (usually recognised as cold fronts over western Europe but as “dry-lines” over the U.S.A.), where an increase of wind with height favours the organisation and intensification of cumulonimbus convection. Extreme instability arises where small-scale convection is confined to a lowermost 1 or 2 km (leading to an abnormally high wetbulb potential temperature) beneath a plume of very warm air lying downwind of an extensive arid plateau (Spain or Mexico). The instability is released where the (backed) low-level flow eventually reaches the edge of the restraining plume aloft. It appears that the occurrence of severe local storms demands a peculiarly favourable combination of geographical features and atmospheric flow-pattern. DOI: 10.1111/j.2153-3490.1968.tb00364.x