EIFFEL LIGHTNING BOLT (艾菲爾鐵塔閃電)－Andrewl8510的部落格

EIFFEL LIGHTNING BOLT:

Believe it or not, bolts of lightning are shooting out of the Eiffel Tower. Photographer Hakim Atek caught it happening on May 25th, 2009:

"I saw some lightning out the window of my home in Paris," says Atek. "So I set up a tripod and pointed my camera at the Eiffel Tower. I never expected to get such an amazing picture."

But did the Tower really make its own lightning? The surprising answer is "yes."

"The upward branching in this photo shows that the Eiffel Tower actually initiated the discharge," says lightning researcher Richard Blakeslee of the NASA Marshall Space Flight Center. "In other words, instead of starting in the cloud and coming to ground, this flash started when the tower 'launched' a leader that propagated upward toward the cloud (which still served as the source of the electric field needed to get the process going). As the leader ascended, it branched out. Eventually one of the branches reached a region of sufficient charge to 'short out the cloud' and produce the return stroke pictured under."

According to Martin Uman's classic text The Lightning Discharge, upward-initiated discharges are "relatively rare," accounting for less than 1% of all lightning, "and generally occur from mountain tops and tall man-made structures." K. Berger, who studied lightning from a mountaintop location 30+ years ago, was one of the first to describe the phenomenon.

艾菲爾鐵塔閃電: 相信它與否, 艾菲爾鐡塔往外射出了閃電. 攝影師 Hakim Atek 在 2009.5.25 拍下這發生的景象: Atek 說 "我在巴黎的家窗外看見一些閃光, 所以我設置好三腳架並讓我的相機對準艾菲爾鐡塔, 我並不期待能拍到一些令人驚奇的照片", 但這鐡塔真的能讓本身發出閃光嗎, 這驚訝的答案是肯定的.

美國太空總署馬歇爾太空飛行中心的閃電研究員 Richard Blakeslee 說 "在這張照片顯示艾菲爾鐡塔竟然開始向上發射有分枝的閃電", 換句話說這並不是在雲層裡產生並且抵達地面的, 當鐡塔開始發射閃電, 並向上傳導到雲層 (需要一直是這電場的來源才能持續進行). 當前端的閃電上升, 就會往外散開. 最後的一道分支到達一個充沛的 '短路雲" 發電地帶, 並產生以下的回擊照片".

根據 Martin Uman 的最經典原文 "閃電發射", 往上引發的閃電是相對罕見的, 佔不到所有閃電中的 1%, 在山頂研究閃電超過30年的Berger 也說"這通常發生在山頂上與人工所建製的", 他是第一個敘述這現象的人.

(以上由 Andrew Ling 翻譯自美國太空氣象網站 2009.05.28)