Margaret Ferguson, age 12 of Penella, Ont.
What causes the lightning?
A dramatic thunderhead is a powerhouse of electricity, which is why we sometimes call it an electric storm. It can generate enough electricity to light a city and perhaps someday we shall figure out how to put all this raging energy to wcrk for us. Thunderstorms seem few and far between, even where they happen most often, but at any time day or night there is always a large number of them raging here and there over land and sea,
The electrical energy in a thunderhead is caused by the activity of tiny electrons. These are the particles charged with negative electricity, swarming around the nucleus of the atom. Each atom, of course, has a quota of positively charged protons in its nucleus. Normally, the number of protons equals the number of electrons and the atom has an equal amount of positive and negative electrical units.
Positive and negative electricity attract each other, somewhat like the two opposite poles of a magnet. A normal atom is electrically neutral and the nucleus, it seems, likes to keep things this way. For, when an electron is lost, the lopsided atom becomes a restless ion, seeking to set right its electrical balance. The protons locked within the nucleus cannot leave home. But the electrons often behave like runaway children, tripping off from one atom to the next.
When a substance has a surplus of electrons, it naturally has a surplus charge of negative electricity. When its atoms lose a large number of its light‑footed electrons, a substance has a positive charge of electricity. When either of these situations becomes too intense, the surplus charge of electricity must be discharged. This happens in a small way when you make a spark by touching something on a frosty morning.
It happens in a big way in a thunderstorm,
The earth usually has a slight charge of negative electricity. In the whirling turmoil of a thunderstorm, countless atoms lose electrons and become ions: Some parts of the cloud build up huge positive.and others huge negative, charges of electricity. When the surplus electricity reaches a peak, it is discharged in a flash of lightning. The fiery streak may be between two parts of the cloud or between the cloud and the ground. In a flash, the surplus electricity becomes a fiery finger, strong enough to sunder a mighty tree.
Though the flash is over in less than a second, several streaks may zoom along the same path. The first streak, or leader, may start from the cloud or from the earth. This may be why some people claim that lightning is caused by ground electricity; The earth, of course, does not send forth lightning unless the powerhouse of a thunderstorm happens to be overhead.