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Short answer

Inside a thunderstorm, collisions between ice particles separate electric charge. Lightning is a giant spark between opposite charges, either inside the cloud or between the cloud and the ground. The spark heats the air to about 50,000 °F, and the air expands so fast it makes thunder. [S1][S2]

Key points

• Two main kinds: intra-cloud lightning and cloud-to-ground lightning. [S1][S2]
• Heat: a lightning channel briefly heats the air to around 50,000 °F, hotter than the Sun's surface. [S1][S2]
• How far away? Sound travels about a mile every 5 seconds. Count the seconds from flash to thunder and divide by 5 for miles. [S1]
• Safety: if you can hear thunder, you are close enough to be struck; go to a safe place. [S1]

Claims

• id: C1 claim: Lightning occurs between opposite charges within a cloud or between cloud and ground. source: S2 evidence: "Lightning can occur between opposite charges within the thunderstorm cloud"
• id: C2 claim: Lightning can heat the air to 50,000 degrees Fahrenheit. source: S1 evidence: "it can heat the air to 50,000 degrees Fahrenheit"
• id: C3 claim: Thunder travels about a mile every 5 seconds. source: S1 evidence: "The sound of thunder travels about a mile every 5 seconds."
• id: C4 claim: Heating from the lightning channel makes the air explode outward, causing thunder. source: S2 evidence: "This causes the air to explode outward."

Sources

• [S1] Understanding Lightning Science. NOAA NWS. https://www.weather.gov/safety/lightning-science-overview . License: US government work, public domain. Accessed 2026-11-04.
• [S2] Severe Weather 101: Lightning Basics. NOAA NSSL. https://www.nssl.noaa.gov/education/svrwx101/lightning/ . License: US government work, public domain. Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).

@misc{iil_note_84caqax7,
  author = {{iinventedlight}},
  title = {{How lightning and thunder work}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-04},
  url = {https://iinventedlight.com/library/notes/lightning-basics/},
  note = {Permanent ID iil:note:84caqax7. License: CC-BY-4.0.},
}

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