FLSC Message Board: Science and Nonsense

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Science and Nonsense

Posted by Ray on 6/2/2009, 10:25 am
69.205.81.50

If you get sassy with Mother Nature, you will get your face slapped...and hard. Sailors know this, and so do people who work and play in the ocean of air around our planet. We humans with our fancy technology think we can act with impunity.

Instead of focusing on the devastating impact on the family and friends of the victims of the French airliner which went down yesterday, media pundits and so-called "experts" have been promulgating their "analysis" of the cause. One such stated this morning on a national network that "there is an infinitesimal chance that lightning brought the plane down". Yesterday, some French official said if lightning was the cause "it would be the first time in history this has ever happened...I just don't believe it."

Hanging on a stairwell in the Atmospheric Sciences building at SUNY Albany, there was a large piece of wing from a commercial jet which had crashed in a storm, killing everyone. The NTSB reported that lightning was the direct cause. Now, on that wing, there was pasted an arrow, which pointed to a very small hole you wouldn't otherwise have noticed, only a few millimeters in size. That was the probable entrance point of the lightning strike.

I don't know what caused yesterday's tragedy, and no one else does either. What we do know is that severe storms and aircraft don't mix well, for in addition to lightning there is extreme turbulence and hail, either of which can also bring down an airplane. Readers of this know that metal aircraft offer good protection against lightning because they constitute a "Faraday Cage", or more accurately, Maxwell's equations show the electric field inside a hollow conductor must be zero. Not because "they are designed to ward off lightning". However, when aircraft are struck, the current flow, although mostly on the surface, can be over one hundred thousand amperes, and the channel temperature, which is thousands of degrees Celsius, both can and do wreck all sorts of havoc, and lightning aircraft "kills" are very well documented, for example see:

probablehttp://books.google.com/books?id=TuMa5lAa3RAC&pg=PA366&lpg=PA366&dq=airc raft+lightning+accidents&source=bl&ots=quYygAdjoz&sig=etTkOqDcJamzIx4isVdU5sP9FaI& hl=en&ei=JywlSr6FJo_tlAfD9anmBw&sa=X&oi=book_result&ct=result&resnum=3

Actually it's a wonder more aircraft aren't brought down by lightning, since cloud-to-cloud discharges are many times more numerous that the cloud-to-ground strikes we are used to seeing, and aircraft are indeed hit frequently (the euphemism "static discharge" is what people are told over the intercom). So, it is statistically true that lightning is rarely the cause of a crash. If aircraft didn't go into bad storms, period, it wouldn't happen. But then, the airlines would lose a lot of money.

Respect....Priceless.

Ray