Early electrification and precipitation development in a small, isolated Montana cumulonimbus
Early electrification and precipitation development in a small, isolated Montana cumulonimbus
复制标题
DOI：
10.1029/jd091id01p01231
复制
发表时间：
1986-01
影响因子：
--
通讯作者：
J. Dye;J. J. Jones-J.;W. Winn;T. A. Cerni;B. Gardiner;D. Lamb;R. Pitter;J. Hallett;C. Saunders
中科院分区：
文献类型：
--
作者：
J. Dye;J. J. Jones-J.;W. Winn;T. A. Cerni;B. Gardiner;D. Lamb;R. Pitter;J. Hallett;C. Saunders
利用仪器飞机和雷达对发生在美国蒙大拿州东南部的一次小型雷暴生命周期的微物理、电学和动力学演变进行了研究。观测开始于降水发展的初期，持续到增长的活跃阶段，云层产生直径达8至9毫米的霰，高空反射率为45 dBZ，并持续到消散阶段，此时只剩下一个带有轻降水痕迹的砧。发现最大的颗粒和降水的主要发展发生在上升气流的边缘。直到5 mm霰、10 L−1的冰粒浓度和35 dBZ的反射率已经存在，云内电场才超过100 V m−1，但随后迅速带电，在8分钟后产生单次云内放电，接近微物理发展的峰值。在云电性发展的早期，当观测到的电场仅为200 V m−1时，在7 km（−20°C）高度附近观察到负电荷积累，并与高反射率区域相关。在降水沉降的早期阶段，4.5公里附近的粒子电荷测量显示主要是带负电荷的粒子，这似乎与从云中落下的降水有关。在观察到的大于100 μm的颗粒中，小于5% ~ 10%的颗粒携带的电荷大于5pc（仪器的检测限）。这些观测结果从雷暴中电荷产生的角度，特别是从碰撞冰粒之间的电荷转移的角度进行了讨论。
Instrumented aircraft and radar were used to investigate the microphysical, electrical, and dynamic evolution of the life cycle of a small thunderstorm which occurred in southeastern Montana. The observations commenced as precipitation development was just beginning, continued through the active stage of growth as the cloud produced graupel up to 8 to 9 mm diameter and reflectivities aloft of 45 dBZ, through the dissipation stage when only an anvil with a trail of light precipitation remained. The largest particles and the primary development of precipitation were found to occur in the fringes of the updraft. The electric fields inside the cloud did not exceed 100 V m−1 until 5 mm graupel, ice particle concentrations of 10 L−1, and reflectivities of 35 dBZ were already present, but then rapidly electrified to produce a single intracloud discharge 8 min later, near the peak of microphysical development. Early in the electrical development of the cloud when observed electric fields were only 200 V m−1, negative charge accumulation was observed near the 7 km (−20°C) level and was associated with the high reflectivity region. In the early stages of precipitation fallout, particle charge measurements near 4.5 km showed primarily negatively charged particles which appeared to be associated with precipitation falling from the cloud. Less than 5 to 10% of the observed particles larger than 100 μm were carrying charges larger than 5 pC, the detection limit of the instrument. These observations are discussed from the point of view of charge generation in thunderstorms, particularly, charge transfer between colliding ice particles.