St. Elmo's Fire
This phenomena has also been called "Foxfire" and it is a phosphorescent light, in the context of the old wild west, often seen on the tips of the cattle's horns and at times on the ears of horses, during stormy nights, or when electricity is in the air.
The phenomenon is scientifically known as a corona or point discharge. It occurs on objects, especially pointed ones, when the electrical field potential strength reaches about one thousand volts per centimeter.
During fair weather, the electrical field strength of the atmosphere is about 1 volt per centimeter. In the initial stages of thunderstorm formation, however, the field increases to 5 volts per centimeter, and just before a lightning flash, reaches ten thousand volts per centimeter. Thus, the atmospheric electrical field is only strong enough, under normal circumstances, to produce St. Elmo's Fire during thundery weather. When the storm is particularly heavily charged, leaves, blades of grass and even the horns of cattle may glow at their tips. In fact, the glow of St. Elmo's Fire has often been observed on sharp objects in the vicinity of tornadoes.