Red sprites over thunderstorms in the coast of Shandong Province,China

【摘要】 Red sprites, different from lightning flashes occurring in the troposphere, are large and brief dis-charges which appear in the altitude range from about 40 to 90 km above large thunderstorms and are usually caused by cloud-to-ground lightning discharges (CGs). A total of 17 sprites over two thunder-storms were first observed during the summer of 2007. One of the sprites occurred on July 28 above a thunderstorm in Guan County and the center of the storm was about 272 km from the observation site. The other sprites were recorded at the late night of August 1 and in the early morning of August 2, and the storm center was about 315 km away. All of the observed sprites occurred in cluster, and their appearances were very different, including ’columniform sprites’, ’columniform sprites’ with angel-like wings, ’carrot sprites’, ’dancing sprites’, etc. The duration of the sprites varied from a minimum of 40 ms to a maximum of 160 ms with a geometric mean (GM) of 61 ms. The time delay between parental positive cloud-to-ground lightning flashes (+CGs) and the associated sprites varied from 3.4 to 11.8 ms with a GM of 7.1 ms. The ratio of the number of +CGs to the total number of CGs during the time period with sprites was 7 times larger than that when no sprites occurred. Sprites did not appear fre-quently at the time when the convective activity is strong but when the thunderstorm starts to become weak.更多还原

【Abstract】 Red sprites, different from lightning flashes occurring in the troposphere, are large and brief dis-charges which appear in the altitude range from about 40 to 90 km above large thunderstorms and are usually caused by cloud-to-ground lightning discharges (CGs). A total of 17 sprites over two thunder-storms were first observed during the summer of 2007. One of the sprites occurred on July 28 above a thunderstorm in Guan County and the center of the storm was about 272 km from the observation site. The other sprites were recorded at the late night of August 1 and in the early morning of August 2, and the storm center was about 315 km away. All of the observed sprites occurred in cluster, and their appearances were very different, including ’columniform sprites’, ’columniform sprites’ with angel-like wings, ’carrot sprites’, ’dancing sprites’, etc. The duration of the sprites varied from a minimum of 40 ms to a maximum of 160 ms with a geometric mean (GM) of 61 ms. The time delay between parental positive cloud-to-ground lightning flashes (+CGs) and the associated sprites varied from 3.4 to 11.8 ms with a GM of 7.1 ms. The ratio of the number of +CGs to the total number of CGs during the time period with sprites was 7 times larger than that when no sprites occurred. Sprites did not appear fre-quently at the time when the convective activity is strong but when the thunderstorm starts to become weak.更多还原