Editing Thunder (section)

== Perception ==
{{Listen
| filename     = Very close thunder cracks.flac
| title        = Thundercracks
| description  = Sample of sharp cracking sounds of thunder heard immediately after nearby lightning strikes
| format       = [[Flac]]
| filename2    = Thunder crack 2B.ogg
| title2       = Crack of thunder
| description2 = A ''crack of thunder'' during the sound of falling rain
| filename3    = Booming Thunder 2023-10-09 2-07-34 am.ogg
| title3       = Thunder boom
| description3 = A ''thunder boom''
}}

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 {{Convert|343|m/s|ft/s|abbr=on}} or {{convert|1236|km/h|mi/h|abbr=on}} at {{Convert|20|C|F K}}.<ref>{{cite book |title=Handbook of Chemistry and Physics, 72nd edition, special student edition |page=14.36|publisher=The Chemical Rubber Co. |year=1991 |location=Boca Raton |isbn=978-0-8493-0486-6}}</ref> 

This translates to approximately {{Convert|3|s/km|s/mi|abbr=on}}; saying "one thousand and one... one thousand and two..." is a useful method of counting the seconds from the perception of a given lightning flash to the perception of its thunder (which can be used to gauge the proximity of lightning for the sake of safety). To estimate the distance from the lightning strike, divide the counted seconds by five for miles,<ref>{{cite web |date=2022 |title=Understanding Lightning: Thunder |url=https://www.weather.gov/safety/lightning-science-thunder |publisher=National Weather Service}}</ref> or three for kilometers.  

A very bright flash of lightning and an almost simultaneous sharp "crack" of thunder, a ''thundercrack'', therefore indicates that the lightning strike was very near.

Close-in lightning has been described first as a clicking or cloth-tearing sound, then a cannon shot sound or loud crack/snap, followed by continuous rumbling.<ref name = Vavreketaln.d. /> The early sounds are from the leader parts of lightning, then the near parts of the return stroke, then the distant parts of the return stroke.<ref name = Vavreketaln.d. />