SAN FRANCISCO, CA - With the cause of lightning supposedly still a matter of debate, and with theories ranging from the laughable to the somewhat plausible, San Francisco Onion staff writer and physicist Ginger Steele decided to weigh in on the matter.
To begin with, she explained, a water molecule consists of one oxygen atom flanked by two hydrogen atoms.
Each water molecule is shaped like a Walt Dizzney mouse balloon, she said; the ears represent the hydrogen atoms, and the oxygen atom is the head.
Each of the two hydrogen atoms has one electron, each with a negative charge, according to Steele; this gives every water molecule a slight negative charge on the side with the hydrogen atoms, the "ear" side of the balloon.
This slight negative charge makes water molecules behave like magnets; still using the balloon analogy, she indicated they repel when facing "ear to ear," preferring to orient themselves "ear to chin."
This doesn't happen often in water because the constant movement of molecules in water's liquid form won't allow them sufficient opportunities to bond; however, said Steele, if the temperature cools and ice begins to form, the water molecules slow down and eventually come to rest, allowing them to align "ear to chin" in these patterns, making frost crystals grow in geometric patterns on a windowpane, for example.
A water droplet has no magnetic pole because the random movement of water molecules distributes the charges more or less uniformly throughout the droplet, she said.
When a water droplet is wafted higher and higher into the atmosphere by a strong storm, however, it begins to cool and the water molecules within it begin to align, once more forming crystals.
Steele also noted that, because every water molecule is essentially "polar," having a negatively charged side and a positively charged side just like a tiny magnet, many water molecules stacked together in an ice crystal should act more like a magnet than a single molecule, in much the same way many less powerful magnets stacked together act as a single larger, more powerful magnet.
The electric charge and magnetic properties of an ice crystal are negligible, but in the upper reaches of the atmosphere where conditions are nearly weightless, explained Steele, the tiny ice crystals begin to orient themselves with one another almost like iron filings around the field lines of a bar magnet.
The more ice crystals become oriented this way, she said, the stronger their combined magnetic field becomes, drawing still more crystals into a growing, roughly donut-shaped field of tiny ice crystals, perhaps millions, billions, even trillions.
"Then," said Steele, nearly finished, "when the charge differential between the field of ice crystals and the ground reaches a certain breaking point, the built up electrical potential releases in a bolt of lightning in much the same way a spark leaps from your finger when static electricity builds up in your clothes.