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The speed at which light propagates through transparent materials, such as glass or air, is less than c; similarly, the speed of electromagnetic waves in wire cables is slower than c. The ratio between c and the speed v at which light travels in a material is called the refractive index n of the material (n = c / v ).
Lightning is a natural phenomenon, more specifically an atmospheric electrical phenomenon. It consists of electrostatic discharges occurring through the atmosphere between two electrically charged regions, either both existing within the atmosphere or one within the atmosphere and one on the ground, with these regions then becoming partially or wholly electrically neutralized.
The flash of a lightning strike and resulting thunder occur at roughly the same time. But light travels 300,000 km/sec, almost a million times the speed of sound. Sound travels at the slower speed of about 340 m/sec (depending on the temperature), so the flash of lightning is seen before thunder is heard. A method to determine the distance ...
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 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]
About 25 million times a year, lightning strikes the United States, according to the National Weather Service. Approximately 300 people per year are hit, and of those about 30 will die — many ...
In the context of this article, "faster-than-light" means the transmission of information or matter faster than c, a constant equal to the speed of light in vacuum, which is 299,792,458 m/s (by definition of the metre) [3] or about 186,282.397 miles per second.
Conduction, when lightning travels through metal surfaces like wires, plumbing, water faucets, windows and doors, is the biggest risk to people who are indoors, Jensenius said.