What causes the lightning in a thunderstorm?
Lightning strikes before thunder. Thunder results from the air disturbance caused by the sudden heating and expansion of air during the electrical discharge; an occurrence of lightning without thunder is not recorded as a thunderstorm. Lightning strokes occur between clouds, or between clouds and the earth. There are many forms of lightning, such as sheet, streak, beaded, ribbon, forked, heat and globular or ball lightning. The most typical is streak lightning; ribbon, beaded, forked, and heat lightning are variants of streak lightning. Heat lightning is the name often applied to streak lightning far enough away so that no thunder is heard. One of the more beneficial consequences of lightning is that it helps to fix atmospheric nitrogen into an organic form that rain can bring to earth. A less recognized function is that lightning restores electrical equilibrium to the earth. It was calculated as early as 1887 that the earth would lose almost all of its electrical charge in less than a
