2014年5月5日鋒面通過台灣南部近海，激發在衛星影像上可觀測到狹而淺的索狀雲(rope cloud)， 此雲帶分別於4日2300UTC及5日0000UTC和0230UTC通過小琉球、綠島和蘭嶼。本文利用衛星雲 圖、雷達回波，以及小琉球、綠島和蘭嶼氣象站高時間解析度地面觀測資料，對此鋒面前緣索狀雲之形 成及其演變進行分析。結果顯示，在索狀雲過境期間，風向劇變、氣壓驟增及溫度劇降的特徵，此與冷 鋒過境者相同，因此索狀雲為確定鋒面位置相當好的指標。此外，氣壓場顯示，在雲線過境期間具有兩 階段上升的特性，此與雷暴陣風鋒面過境期間所顯現的現象相似。 衛星雲圖顯示，索狀雲呈穩定性移動，其移速約為8.3 ms-1。由地面觀測開始降溫到升溫兩點間的 壓力差計算密度流(density current)速度，其值為9.1 ms-1。密度流速度略高於實際風速及雲線軌跡速度， 係因測站的風速是10分鐘的平均，而軌跡速度是較長時間的平均。

Rope cloud lines triggered by cold front passing south side of Taiwan are visible on the satellite imageries on May 5, 2014. The cloud line passed the Little Liuchou, Ludao and Lanyu on 2300UTC May 4, 0000UTC, and 0230UTC on May 5, respectively. In this study, this rope cloud formed at the leading edge of cold front and subsequent transition are analyzed by satellite imageries, radar reflectivity, and surface observations from these three islands. Results show that the wind direction changes, pressure rises and temperature drops dramatically during the passage. The transition tendencies well match the characteristics of cold front passing which suggests that rope clod lines are good indication of the leading edge of cold front. In addition, the pressure showed two-step rises which is similar to the gust front produced by thunderstorm. Tracking the cloud lines movement from visible satellite imageries, the translation speed is estimated about 8.3 m s-1. On the other hands, using density current formula and surface observation, the speed is about 9.1 m s-1. This speed is slightly higher than the actual wind speed from the surface. However, the surface wind is 10-minute average which suggests that the density model seems applicable.