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Positive lightning is less common than negative lightning and on average makes up less than 5% of all lightning strikes. [ 10 ] A bolt from the blue lightning strike which appears to initiate from the clear, but [ clarification needed ] the turbulent sky above the anvil cloud and drive a bolt of plasma through the cloud directly to the ground.
Lightning currents have a very fast rise time, on the order of 40 kA per microsecond. Hence, although lightning is a form of direct current, conductors of such currents exhibit marked skin effect as with an alternating current, causing most of the currents to flow through the outer surface of the conductor. [32]
The speed of light in vacuum, commonly denoted c, is a universal physical constant that is exactly equal to 299,792,458 metres per second (approximately 300,000 kilometres per second; 186,000 miles per second; 671 million miles per hour).
Cloud-to-ground lightning. Typically, lightning discharges 30,000 amperes, at up to 100 million volts, and emits light, radio waves, x-rays and even gamma rays. [1] Plasma temperatures in lightning can approach 28,000 kelvins. Atmospheric electricity describes the electrical charges in the Earth's atmosphere (or that of another planet).
The speed of this flow has multiple meanings. In everyday electrical and electronic devices, the signals travel as electromagnetic waves typically at 50%–99% of the speed of light in vacuum. The electrons themselves move much more slowly. See drift velocity and electron mobility.
Global map of lightning frequency--strikes/km 2 /yr. The high lightning areas are on land located in the tropics. Areas with almost no lightning are the Arctic and Antarctic, closely followed by the oceans which have only 0.1 to 1 strikes/km 2 /yr. The map on the right shows that lightning is not distributed evenly around the planet. [5]
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The most noticeable aspect of lightning and thunder is that the lightning is seen before the thunder is heard. This is a consequence of the speed of light being much greater than the speed of sound. The speed of sound in dry air is approximately 343 m/s (1,130 ft/s) or 1,236 km/h (768 mph) at 20 °C (68 °F; 293 K). [19]