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For example, for visible light, the refractive index of glass is typically around 1.5, meaning that light in glass travels at c / 1.5 ≈ 200 000 km/s (124 000 mi/s); the refractive index of air for visible light is about 1.0003, so the speed of light in air is about 90 km/s (56 mi/s) slower than c.
Lightning is usually produced by cumulonimbus clouds, which have bases that are typically 1–2 km (0.62–1.24 mi) above the ground and tops up to 15 km (9.3 mi) in height. The place on Earth where lightning occurs most often is over Lake Maracaibo , wherein the Catatumbo lightning phenomenon produces 250 bolts of lightning a day. [ 76 ]
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]
But light travels 300,000 km/sec, almost a million times the speed of sound. ... that is, if the lightning is closer than 8 km or 5 miles.
The jet was initially observed to be traveling up at around 50 km/s (110,000 mph; 180,000 km/h) at a speed similar to typical lightning, increased to 160 and 270 km/s (360,000–600,000 mph; 580,000–970,000 km/h), but then split in two and sped upward with speeds of at least 2,000 km/s (4,500,000 mph; 7,200,000 km/h) to the ionosphere where ...
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] About 70% of lightning occurs on land in the Tropics, where ...
Optical imaging using a 10,000 frame-per-second high speed camera showed that sprites are actually clusters of small, decameter scale, (10–100 m or 33–328 ft) balls of ionization that are launched at an altitude of about 80 km (50 mi) and then move downward at speeds of up to ten percent the speed of light, followed a few milliseconds later ...
Lightning is detected remotely using sensors that detect cloud-to-ground lightning strokes with 95 percent accuracy in detection and within 250 metres (820 ft) of their point of origin. [105] Summer storm in 19th-century Polish countryside – picture by Jozef Chelmonski, 1896, 107 cm (42.1 in)x163 cm (64.1 in), National Museum in Cracow