Lightning Strikes

In Focus on Lightning Strikes. "Worldwide, lightning strikes around 50 times every second (more than 4 million times every day). Electrical imbalances generated by turbulent skies are suddenly balanced by a spectacular discharge tracing across a darkened sky -- a display that is both frightening and awe-inspiring. Collected below are recent images of lightning around the world, including a rare image of an upper atmosphere 'red sprite' flash captured by NASA astronauts aboard the International Space Station. [24 photos]"