Cloud to ground Lightning in the global atmospheric electrical circuit. This is an example of plasma present at Earth's surface. Typically, lightning discharges 30,000 amperes, at up to 100 million volts, and emits light, radio waves, x-rays and even gamma rays. Plasma temperatures in lightning can approach 28,000 kelvins and electron densities may exceed 1024/m3.

Fonte: http://en.wikipedia.org/wiki/File:Lightning_over_Oradea_Romania_3.jpg