時差N小時:海洋獨特的磁場
上次，我們提到過動生電磁感應(yīng)：海洋產(chǎn)生磁場的一種現(xiàn)象。
It works like this: earth has its own magnetic field.
地球有自己的磁場，
The oceanhas plenty of charged atoms in it, in the form of dissolved salt.
海洋有無數(shù)溶解鹽形式的帶電原子，
These atoms are in motion because the ocean flows.
隨著海洋運動而運動。
Charged atoms moving through a magnetic field will induce an electric current.
在磁場中運動的帶電原子會引起電流，
And an electriccurrent will, in turn, create another magnetic field.
而電流反過來又回形成另一個磁場。
The ocean should generate its own magneticfield.
這樣海洋應(yīng)該就形成了自己的磁場。
You said should. How could we know this “motional induction” is happening?
你說“應(yīng)該”，我們怎么知道這種動生電磁感應(yīng)確有其事?
Direct evidence came in 2003 from scientists working at the University of Washington and aresearch institute in Potsdam, Germany.
直到2003年，華盛頓大學(xué)和德國波茲坦的某研究學(xué)院。
These researchers used a magnetometer on board anorbiting satellite.
研究人員將磁力計放在軌道衛(wèi)星上，證實海洋的磁場真是存在。
First, they figured out what the magnetic field of the planet should be.
最初，磁力計上的數(shù)據(jù)讓科學(xué)家以為是地球磁場作用的。
After subtracting thisfigure, they found there was still some leftover magnetic field.
而后，他們發(fā)現(xiàn)除去這個因素后，仍然有磁場存在。
Next, the team made a computer model of what kind of magnetic field the ocean shouldgenerate through motional induction.
研究人員又電腦模擬在動生電磁感應(yīng)讓海洋產(chǎn)生哪種磁場，
Sure enough, their prediction matched the excessmagnetic field measured by the satellite.
當(dāng)然，科學(xué)家的推論和衛(wèi)星上測出的“另一個”磁場吻合。
The satellite also found that magneticintensity over the oceans peaked every twelve and a halfhours, but not over the land. Can you guess why?
衛(wèi)星還發(fā)現(xiàn)，海洋磁場每隔12個半小時就會出現(xiàn)高峰，但是地球磁場不受影響。你能猜到原因嗎?
Every twelve hours…Oh, I get it— tides!
每隔12個半小時?我知道了!答案是潮汐。
Exactly right!
完全正確!
The tides rise and fall every twelve and half hours, just as that extra magneticenergy swells and diminishes.
潮汐每隔12個半小時潮起潮落，正好和“另一個”磁場高低峰吻合。
This is very strong evidence that motional induction is real… andthe ocean has its own magnetism.
這正是磁場感應(yīng)存在的真憑實據(jù)，海洋確實有自己獨特的磁力。
