南極長年冰天雪地，人跡罕至，不少奇怪異象都是世人從未見過，英國廣播公司（ BBC）攝製隊，早前首次在南極海底拍攝到“死亡冰柱”（ icicle of death），冰柱下沉到海床后，所到之處周遭的海水都會凝結，海膽、海星全被凍死，蔚為奇觀。
其實這種死亡冰柱自 1960年代已開始存在，通常當南極海洋混入了帶鹽份的水后就會出現，不過今次還是首度有人拍攝到這個奇景。拍攝當日，海底水溫只得-2℃， BBC攝影師米勒（ Hugh Miller）及安德森（ Doug Anderson）在南極羅斯群島（ Ross Archipelago）的小剃刀背島（ Little Razorback Island）海中，親眼目擊死亡冰柱的形成過程。
由於冰柱的密度較海水高，因此一直朝海床沉下，並迅速擴張，周遭接觸到冰柱的海水隨即變冷凝固，但看上去像海綿狀多過普通海冰，而附近的海洋生物，如海膽及海星等，因冰柱的溫度太低而全被凍死。
米勒憶述當日親眼目擊冰柱沉下並迅速擴張，仍感到有點難以置信，“這情況有點像與時間競賽，因為沒有人真正知道它們形成得有多快。我們一星期前看到的那條冰柱，在我們面前迅速擴張變長，整個過程只用了5、6小時。”
Remarkable broadcast moment: The ice begins to expand outwards. The brine is a lot more dense than seawater so sinks to the bottom. It is also a lot colder - causing the freezing
Touchdown: The brinicle reaches the ocean floor. Starfish can be seen. Often the brinicles break up before they become so large
Killer: The ice floods outwards across the ocean surface rapidly, destroying everything in its wake
Destruction: The starfish are frozen by the ice as it expands outwards
Broadcasting feat: Although the existence of brinicles has long been known it is the first time they have ever been caught on camera
Seabed spread: When the seawater freezes as it comes into contact with the brinicle it is a lot more spongelike than normal ice |
發表於 2014-12-3 09:35 AM
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