How we worked it out
Updated as you change the numbers.
- v = 331.3 × √(1 + T ÷ 273.15) m/s, with T in °C.
Method and assumptions
For dry air; humidity raises it slightly. About 3 seconds per kilometer (5 per mile) is the usual lightning rule.
Questions
How fast is sound at 20 °C?
About 343.2 m/s; thunder 6 seconds after the flash is about 2.06 km away.
Sources
Method and figures checked on . Every worked answer on this page is covered by an automated test. Found a mistake? Tell us.