Linda Hogue, Age 14, Of Spokane, Wash., for her question:
What causes saint elmo's fire?
When sudden storms lashed down upon the Mediterranean, the sailors counted on their Saint Erasmus to save them from the plunging waves. They also called this guardian of sailing ships st. Ermo or st. Elmo, and the pink and sputtering lights of St. Elmo's fire were an omen of good luck.
The pink candles of st. Elmo flicker without smoke and crackle without burning. They are electrical discharges from the stupendous forces generated by a thunderstorm and related to crackling hairbrushes and static sparks, to electric arcs and flashing lightning. Electrical events are caused by electrons, and a turbulent storm sweeps swarms of these negative particles from their parent atoms and molecules.
At the atomic leve1, there are opposite charges of positive and negative electricity. Positive and negative charges attract each other somewhat like the opposite poles of a pair of magnets. A proton particle carries a positive charge equal and opposite to the negative charge of an electron. Normally an atom is balanced with an equal number of protons and electrons.
But its protons are locked in the atomic nucleus and its orbiting electrons are more free to come and go. On a small scale, electron hopping between objects at ground level goes on all the time. As an electron departs, it leaves its parent molecule with an extra positive charge. The shorn molecule becomes a positive ion, eager to regain its balance by attracting another negative particle. In the weathery warfare of a storm, swarms of electrons are torn from the atoms and m01ecuies of the atmosphere.
The ions and footloose electrons generate tremendous charges of electricity seeking to discharge thmselves and restore the electrical balance. The discharge occurs
Between a highly charged field and one less highly charged. The lightning tends to flash between the gigantic charges within a storm cloud and the small weak field around a steeple spire.
When conditions are right, the electrified atmosphere is attracted to the mast and other points in the rigging of a sailing ship. This causes oxygen m01ecules in the air to became energetic ions. The discharge is carried off as the ghostly lights of st. Elmo's fire. They are pinkish because the discharge affects the nitrogen in the air and the spectrum color of nitrogen is red.
The ghostly tapers often lit the rigging of old sailing ships, but St. Elmo's fire never visits our steam driven ships of steel. However, sometimes it dances and crackles on the nose and wing tips of a plane flying through a thunderhead. But its pretty displays are unwelcome. The electrical discharges can black out radio contact and make other instruments useless. In this age of science, our planes are fitted with gadgets to discourage the playful pranks of St. Elmo.