Why does it rain harder after a flash of lightning?

That it often rains harder after a vivid flash of lightning and heavy peal of thunder is a fact well known to meteorologists. Strictly speaking, however, the rain gush, as weather experts call it, is caused by neither the lightning nor the thunder. According to the United States Weather Bureau, a cloud is electrified when raindrops are produced by a rapidly rising mass of warm humid air. The greater the. quantity of raindrops produced, the greater, in general, will be the quantity of electricity. Therefore, when a large number of raindrops have been formed in a cloud, there is often a correspondingly heavy discharge of lightning, followed by thunder. The light from the discharge, the thunder and the raindrops all start down at the same time; but the light, being much faster, is seen before the thunder is heard, and the drops, being slower even than the thunder, follow immediately. In other words, the action of the rising air on. the raindrops causes the lightning, and the lightning causes the thunder.