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Evidence record

What is lightning?

Every sentence on the exploration belongs to at least one claim below. Each says what kind of statement it is, what it rests on, what the evidence does not establish, and how far it was checked. Nothing here is a score, and none of it is a verdict on a belief or a theory.

Last checked 24 September 2026.

  • A judgement, not a fact: 10
  • Partly checked: 19
  • Source checked: 28
  • Presented as open: 4

If something here is wrong, misquoted, out of date or unfair, write to support@unknownoceans.com and give the claim number, which does not change.

What the question takes for granted

A scientific question with a settled half and an open half. How a flash propagates is measured in detail; how it starts, in fields weaker than breakdown needs, is argued between observers and modellers.

  • Lightning is a discharge of charge separated inside the cloud

    Established

    The charge structure and its origin in collisions are the agencies' and the field's standard account; the details of the charging are not.

  • The fields measured in clouds are the fields where lightning starts

    Open

    The initiation problem depends on it. Instruments may miss compact regions of strong field, which is one of the ways out that the page reports.

  • There is one mechanism that starts lightning

    Contested

    One group reports that fast positive breakdown starts many or possibly all flashes; its follow-up found fast breakdown of negative polarity too, and the runaway mechanism is still proposed.

How the question is labelled

Claim: The spark that should not start

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

The page's own figure for the initiation problem: measured cloud fields are below what breakdown of air needs, and lightning happens anyway (claims 3 and 8).

Claim 1 · checked 24 September 2026 · AI-assisted audit

Claim: Lightning

Kind
Framing. Signposting. It asserts nothing a source could check.

The question

Claim: Thunderclouds have never been measured with a field strong enough to break down air the ordinary way.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

What this does not establish

Petersen and others was read as an abstract. "Never measured" is a statement about measurements: regions of strong field small enough to escape the instruments are not ruled out.

Later work looked for

Europe PMC, 2016 on, "lightning initiation": Tilles and others (2019) still describe measured fields as well below the breakdown threshold; nothing that changes it.

Claim 3 · checked 24 September 2026 · AI-assisted audit

Claim: They produce lightning anyway, about forty-four times a second worldwide.

Kind
Present-day figure. A count, survey or report finding, as the named source gives it.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

What this does not establish

Read as an abstract. The figure counts flashes, cloud and ground together, from satellite optical detection; the uncertainty is mostly in how many flashes the instrument misses.

Later work looked for

Crossref, 2003 on, "lightning climatology OTD LIS": the gridded climatologies of 2014 and 2026 extend the satellite record, and no abstract read gives a different global rate. The page's older figure of fifty to a hundred, from Britannica, was replaced with the satellite measurement.

Corrected

24 September 2026. Previously: “They produce lightning anyway, fifty to a hundred times a second worldwide.” Fifty to a hundred is the traditional estimate, which the satellite count says was derived in 1925 from thunder-day records. The Optical Transient Detector measured 44 ± 5 flashes a second, and the interlude's "forty" disagreed with the subtitle besides.

Claim 4 · checked 24 September 2026 · AI-assisted audit

Claim: The behaviour of lightning is documented in extraordinary detail

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

Follows from the measured sequence and figures in claims 15 to 19.

Claim 5 · checked 24 September 2026 · AI-assisted audit

Claim: down to radio images of the first microseconds of a flash.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

Later work looked for

How the instrument works; not a finding later work revises.

Corrected

24 September 2026. Previously: “down to microsecond photography of a strike forming.” No cited source describes microsecond photography. The cited interferometry images a flash's first microseconds in VHF radio.

Claim 6 · checked 24 September 2026 · AI-assisted audit

Claim: What starts it is not established

Kind
Open question. Something the page says is not known.
Review
Presented as open. The page says this is unresolved, and the review found that it is.

  • Supports

    Fast negative breakdown in thunderstormsIntroduction, first paragraph

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Observational study: associations, not causes

    The source reads: Despite over 250 years of dedicated research ... the details of lightning initiation remain unknown.

Claim 7 · checked 24 September 2026 · AI-assisted audit

Claim: the fields measured inside thunderclouds are lower than most proposed mechanisms require.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

  • Supports

    The initiation of lightning by runaway air breakdownabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · A simulation · Model

    The source reads: The ambient electric field strength needed for this mechanism is within the range of values observed in thunderclouds and is substantially lower than that required by most other mechanisms.

  • Supports

    A brief review of the problem of lightning initiation and a hypothesis of initial lightning leader formationabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Earth and its record · Review of the field

    The source reads: The historically favored positive streamer mechanisms are problematic due to requiring electric fields two to three times larger than peak observed fields.

  • Supports

    Observations of narrow bipolar events reveal how lightning is initiated in thunderstormsDiscussion

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Observational study: associations, not causes

    The source reads: For hydrometeor-initiated streamers, the required field strength is estimated by Petersen et al. ... to be at least a factor of two greater than the largest electric fields observed in storms

What this does not establish

Dwyer and Petersen were read as abstracts; Rison in full. "Most" is Dwyer's word, and the mechanism he proposes is one of the few said to work at observed fields. Compact regions of strong field could exist that in situ instruments have missed, as Rison and colleagues note.

Later work looked for

Europe PMC, 2016 on, "lightning initiation": Tilles and others (2019) still describe measured fields as well below the breakdown threshold; nothing that changes it.

Claim 8 · checked 24 September 2026 · AI-assisted audit

Claim: Lightning is the most familiar high-energy phenomenon on the planet

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

A framing judgement; the page does not rest anything on it.

Claim 9 · checked 24 September 2026 · AI-assisted audit

Claim: and how it starts is still not known in detail.

Kind
Open question. Something the page says is not known.
Review
Presented as open. The page says this is unresolved, and the review found that it is.

  • Supports

    Fast negative breakdown in thunderstormsIntroduction, first paragraph

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Observational study: associations, not causes

    The source reads: Despite over 250 years of dedicated research ... the details of lightning initiation remain unknown.

Corrected

24 September 2026. Previously: “Lightning is the most familiar high-energy phenomenon on the planet and one of the least explained.” The page itself documents lightning's behaviour in detail; what is unexplained is its initiation, which is what the source says.

Claim 10 · checked 24 September 2026 · AI-assisted audit

Claim: Balloons and aircraft have flown instruments through thunderclouds for decades.

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Gamma ray glow observations at 20-km altitudeIntroduction

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Review of the field

    The source reads: Several balloon experiments were performed over Oklahoma during the 1990s. ... More recently, gamma ray glows have been observed during a few aircraft campaigns. ... large enhancements (2–3 orders of magnitude) lasting for tens of seconds have been observed inside the thundercloud

What this does not establish

The flights this source reviews carried radiation detectors; the field measurements themselves are summarised by Petersen and others and by Rison and others.

Claim 11 · checked 24 September 2026 · AI-assisted audit

Claim: The fields they measure are lower than most of the proposed mechanisms need in order to start a spark.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

  • Supports

    The initiation of lightning by runaway air breakdownabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · A simulation · Model

    The source reads: The ambient electric field strength needed for this mechanism is within the range of values observed in thunderclouds and is substantially lower than that required by most other mechanisms.

  • Supports

    A brief review of the problem of lightning initiation and a hypothesis of initial lightning leader formationabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Earth and its record · Review of the field

    The source reads: The historically favored positive streamer mechanisms are problematic due to requiring electric fields two to three times larger than peak observed fields.

  • Supports

    Observations of narrow bipolar events reveal how lightning is initiated in thunderstormsDiscussion

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Observational study: associations, not causes

    The source reads: For hydrometeor-initiated streamers, the required field strength is estimated by Petersen et al. ... to be at least a factor of two greater than the largest electric fields observed in storms

What this does not establish

Dwyer and Petersen were read as abstracts; Rison in full. "Most" is Dwyer's word, and the mechanism he proposes is one of the few said to work at observed fields. Compact regions of strong field could exist that in situ instruments have missed, as Rison and colleagues note.

Later work looked for

Europe PMC, 2016 on, "lightning initiation": Tilles and others (2019) still describe measured fields as well below the breakdown threshold; nothing that changes it.

Claim 12 · checked 24 September 2026 · AI-assisted audit

What it does

Claim: What it does

Kind
Framing. Signposting. It asserts nothing a source could check.

How a flash unfolds

Claim: How a flash unfolds

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: A stepped leader descends from the cloud in steps, branching as it goes, carrying charge downward along a channel of partly ionised air.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Lightning (meteorology)section on cloud-to-ground lightning

    Cited · Link refuses automated checks, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: This process creates a channel of partially ionized air ... a stepped leader (initial lightning stroke) forms and propagates downward, following channels created by the preliminary breakdown process. The leader is highly branched in the direction of its propagation. Most leader channels are negatively charged.

Later work looked for

How the process runs; a reference-work description that later work refines rather than revises.

Corrected

24 September 2026. Previously: “A stepped leader descends from the cloud in steps, branching as it goes, carrying charge downward and establishing an ionised channel.” The reference work has the partly ionised channel made first, by preliminary breakdown, and the leader following it.

Claim 15 · checked 24 September 2026 · AI-assisted audit

Claim: As it nears the ground, an upward connecting discharge of opposite polarity rises and meets it, typically about thirty metres up.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Lightning (meteorology)section on cloud-to-ground lightning

    Cited · Link refuses automated checks, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: When the stepped leader nears the ground, an upward, connecting discharge of opposite polarity rises and meets it at a point typically about 30 metres (100 feet) above the ground.

Later work looked for

How the process runs; a reference-work description that later work refines rather than revises.

Claim 16 · checked 24 September 2026 · AI-assisted audit

Claim: When they meet, the return stroke propagates back to the cloud at about a third of the speed of light.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Lightning (meteorology)section on cloud-to-ground lightning

    Cited · Link refuses automated checks, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: When the junction is complete, the cloud is effectively connected to the ground, and a very bright return stroke propagates back to the cloud at a speed about one-third the speed of light

Later work looked for

Crossref, 2010 on, "return stroke peak current": later work finds peak currents vary with latitude and terrain, which "typically" already allows; nothing that changes the figures.

Claim 17 · checked 24 September 2026 · AI-assisted audit

Claim: Peak currents in return strokes to negative leaders are typically about 30,000 amperes, and the channel reaches about 30,000 degrees Celsius.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Lightning (meteorology)section on cloud-to-ground lightning

    Cited · Link refuses automated checks, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: the peak currents in return strokes to negative leaders are typically about 30,000 amperes. The peak temperatures in the return-stroke channel are on the order of 30,000 °C (50,000 °F).

What this does not establish

Typical values: individual strokes range widely around them.

Later work looked for

Crossref, 2010 on, "return stroke peak current": later work finds peak currents vary with latitude and terrain, which "typically" already allows; nothing that changes the figures.

Claim 18 · checked 24 September 2026 · AI-assisted audit

Claim: A typical flash to the ground contains three or four leader and return-stroke sequences in rapid succession.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Lightning (meteorology)section on cloud-to-ground lightning

    Cited · Link refuses automated checks, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: A typical lightning flash to the ground contains three or four leader-return stroke sequences in rapid succession.

Later work looked for

Crossref, 2010 on, "return stroke peak current": later work finds peak currents vary with latitude and terrain, which "typically" already allows; nothing that changes the figures.

Claim 19 · checked 24 September 2026 · AI-assisted audit

Claim: All of this has been measured.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

A summary of the passage: the figures above are measured values reported by a reference work.

Corrected

24 September 2026. Previously: “All of this is filmed, measured and modelled.” No cited source says the sequence is filmed or modelled; the figures are measured values.

Claim 20 · checked 24 September 2026 · AI-assisted audit

Claim: The engineering follows:

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

Links the physics above to protection, claim 22.

Claim 21 · checked 24 September 2026 · AI-assisted audit

Claim: a lightning rod protects a structure by intercepting the current and diverting it into the ground.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Lightning (meteorology)section on lightning hazards

    Cited · Link refuses automated checks, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: Lightning rods and metallic conductors can be used to protect a structure by intercepting and diverting the lightning current into the ground as harmlessly as possible.

Later work looked for

How protection works; not a finding later work revises.

Corrected

24 September 2026. Previously: “The engineering consequences, how to protect an aircraft or a substation, are well understood.” No cited source discusses aircraft or substations. The reference work describes how a lightning rod protects a structure, and the page now says that.

Claim 22 · checked 24 September 2026 · AI-assisted audit

Claim: One stroke, to the ground

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: tens of ms

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

The stepped leader takes about thirty milliseconds to reach the ground.

  • Supports

    Lightning (meteorology)section on cloud-to-ground lightning

    Cited · Link refuses automated checks, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: the leader stroke reaches the ground in about 30 milliseconds, and the return stroke reaches the centre of the cloud in about 100 microseconds

Later work looked for

How the process runs; a reference-work description that later work refines rather than revises.

Claim 24 · checked 24 September 2026 · AI-assisted audit

Claim: A stepped leader works its way down in steps, branching.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Lightning (meteorology)section on cloud-to-ground lightning

    Cited · Link refuses automated checks, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: This process creates a channel of partially ionized air ... a stepped leader (initial lightning stroke) forms and propagates downward, following channels created by the preliminary breakdown process. The leader is highly branched in the direction of its propagation. Most leader channels are negatively charged.

Later work looked for

How the process runs; a reference-work description that later work refines rather than revises.

Corrected

24 September 2026. Previously: “A stepped leader works its way down in steps, branching, invisible to the eye.” No cited source says the leader is invisible to the eye.

Claim 25 · checked 24 September 2026 · AI-assisted audit

Claim: last metres

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Lightning (meteorology)section on cloud-to-ground lightning

    Cited · Link refuses automated checks, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: When the stepped leader nears the ground, an upward, connecting discharge of opposite polarity rises and meets it at a point typically about 30 metres (100 feet) above the ground.

Later work looked for

How the process runs; a reference-work description that later work refines rather than revises.

Claim 26 · checked 24 September 2026 · AI-assisted audit

Claim: An upward discharge rises to meet it, typically about thirty metres up.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Lightning (meteorology)section on cloud-to-ground lightning

    Cited · Link refuses automated checks, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: When the stepped leader nears the ground, an upward, connecting discharge of opposite polarity rises and meets it at a point typically about 30 metres (100 feet) above the ground.

Later work looked for

How the process runs; a reference-work description that later work refines rather than revises.

Claim 27 · checked 24 September 2026 · AI-assisted audit

Claim: When they join, the cloud is connected to the ground.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Lightning (meteorology)section on cloud-to-ground lightning

    Cited · Link refuses automated checks, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: When the junction is complete, the cloud is effectively connected to the ground, and a very bright return stroke propagates back to the cloud at a speed about one-third the speed of light

Later work looked for

How the process runs; a reference-work description that later work refines rather than revises.

Corrected

24 September 2026. Previously: “Where they connect is where the strike lands.” The junction is about thirty metres up, so it is not where the strike lands; the upward discharge starts from the ground. The reference work says the junction connects cloud to ground.

Claim 28 · checked 24 September 2026 · AI-assisted audit

Claim: microseconds

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

The return stroke reaches the centre of the cloud in about a hundred microseconds.

  • Supports

    Lightning (meteorology)section on cloud-to-ground lightning

    Cited · Link refuses automated checks, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: the leader stroke reaches the ground in about 30 milliseconds, and the return stroke reaches the centre of the cloud in about 100 microseconds

Later work looked for

How the process runs; a reference-work description that later work refines rather than revises.

Claim 29 · checked 24 September 2026 · AI-assisted audit

Claim: The return stroke, at about a third of light speed.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Lightning (meteorology)section on cloud-to-ground lightning

    Cited · Link refuses automated checks, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: When the junction is complete, the cloud is effectively connected to the ground, and a very bright return stroke propagates back to the cloud at a speed about one-third the speed of light

Later work looked for

Crossref, 2010 on, "return stroke peak current": later work finds peak currents vary with latitude and terrain, which "typically" already allows; nothing that changes the figures.

Claim 30 · checked 24 September 2026 · AI-assisted audit

Claim: Peak current about 30,000 amperes, channel about 30,000 degrees Celsius.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Lightning (meteorology)section on cloud-to-ground lightning

    Cited · Link refuses automated checks, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: the peak currents in return strokes to negative leaders are typically about 30,000 amperes. The peak temperatures in the return-stroke channel are on the order of 30,000 °C (50,000 °F).

What this does not establish

Typical values: individual strokes range widely around them.

Later work looked for

Crossref, 2010 on, "return stroke peak current": later work finds peak currents vary with latitude and terrain, which "typically" already allows; nothing that changes the figures.

Claim 31 · checked 24 September 2026 · AI-assisted audit

Claim: rapid succession

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Lightning (meteorology)section on cloud-to-ground lightning

    Cited · Link refuses automated checks, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: A typical lightning flash to the ground contains three or four leader-return stroke sequences in rapid succession.

Later work looked for

How the process runs; a reference-work description that later work refines rather than revises.

Corrected

24 September 2026. Previously: “tens of ms after” The interval between strokes is not in any cited source; the reference work says "in rapid succession".

Claim 32 · checked 24 September 2026 · AI-assisted audit

Claim: Three or four such sequences in a typical flash.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Lightning (meteorology)section on cloud-to-ground lightning

    Cited · Link refuses automated checks, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: A typical lightning flash to the ground contains three or four leader-return stroke sequences in rapid succession.

Later work looked for

Crossref, 2010 on, "return stroke peak current": later work finds peak currents vary with latitude and terrain, which "typically" already allows; nothing that changes the figures.

Corrected

24 September 2026. Previously: “Three or four such sequences in a typical flash, down the same channel, which is what makes the flicker.” That later strokes follow the same channel and cause the flicker is not in any cited source.

Claim 33 · checked 24 September 2026 · AI-assisted audit

Thunderclouds make X-rays and gamma rays

Claim: Thunderclouds make X-rays and gamma rays

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

  • Supports

    X-ray bursts associated with leader steps in cloud-to-ground lightningabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Earth and its record · Measurement

    The source reads: The observed X‐ray emission typically was detected ∼1 ms before the first return stroke, during the stepped‐leader phase

  • Supports

    Gamma ray glow observations at 20-km altitudeIntroduction

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Review of the field

    The source reads: Thunderstorms have been shown to produce a variety of hard radiation ranging from the submillisecond long terrestrial gamma ray flashes

What this does not establish

The X-rays come from lightning leaders rather than from the cloud at rest; the Dwyer paper was read as an abstract.

Later work looked for

Europe PMC, 2006 on, "X-rays lightning leader": later ground observations, including X-rays from upward positive lightning (2024), extend the result; nothing that changes it.

Claim 34 · checked 24 September 2026 · AI-assisted audit

Claim: Lightning emits bursts of X-rays.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

  • Supports

    X-ray bursts associated with leader steps in cloud-to-ground lightningabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Earth and its record · Measurement

    The source reads: The X rays were produced in discrete, intense bursts emitted in coincidence with the formation of the leader steps

  • Supports

    Gamma ray glow observations at 20-km altitudeIntroduction

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Review of the field

    The source reads: These are transients related to leader steps

What this does not establish

The measurement paper was read as an abstract.

Later work looked for

Europe PMC, 2006 on, "X-rays lightning leader": later ground observations, including X-rays from upward positive lightning (2024), extend the result; nothing that changes it.

Claim 35 · checked 24 September 2026 · AI-assisted audit

Claim: Measurements beside five natural strikes in Florida caught them about a millisecond before the first return stroke, during the stepped-leader phase, at energies up to a few hundred thousand electronvolts, in discrete bursts coinciding with the formation of the leader steps.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

  • Supports

    X-ray bursts associated with leader steps in cloud-to-ground lightningabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Earth and its record · Measurement

    The source reads: X‐ray and electric field measurements were made during five nearby negative natural lightning strikes in north central Florida ... typically was detected ∼1 ms before the first return stroke, during the stepped‐leader phase, and had energies extending up to a few hundred keV.

What this does not establish

Five strikes, all negative, at one Florida site; read as an abstract, so the timing distribution and energy spectra were not read.

Later work looked for

Europe PMC, 2006 on, "X-rays lightning leader": later ground observations, including X-rays from upward positive lightning (2024), extend the result; nothing that changes it.

Claim 36 · checked 24 September 2026 · AI-assisted audit

Claim: Thunderstorms also produce flashes of gamma radiation energetic enough to be detected from orbit,

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

What this does not establish

The discovery paper was read as an abstract; the link to thunderstorms is carried by the later paper.

Later work looked for

Europe PMC, 2010 on, "terrestrial gamma-ray flash": work with the ASIM instrument on the space station (Skeie and others 2022) ties the flashes to the early phase of intracloud lightning; the page now says so.

Claim 37 · checked 24 September 2026 · AI-assisted audit

Claim: and those were found by a satellite instrument built to watch for gamma-ray bursts in space.

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    The temporal relationship between terrestrial gamma-ray flashes and associated optical pulses from lightningIntroduction

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Observational study: associations, not causes

    The source reads: TGFs were first reported by Fishman et al. (1994), using the Burst and Transient Source Experiment on the Compton Gamma Ray Observatory.

  • Supports

    The Burst And Transient Source Experiment (BATSE)instrument page

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: The Burst And Transient Source Experiment (BATSE) serves as the all-sky monitor for the Compton Observatory, detecting and locating strong transient sources called gamma-ray bursts as well as outbursts from other sources over the entire sky.

Corrected

24 September 2026. Previously: “and those were discovered by accident by a satellite built to watch for gamma-ray bursts in space.” "By accident" is not in any source; the instrument, not the satellite, was the burst monitor.

Claim 38 · checked 24 September 2026 · AI-assisted audit

Claim: That means electrons inside thunderclouds are being accelerated to relativistic energies,

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

What this does not establish

An inference from the spectra, which is how the field reads them; where and how the electrons are accelerated, near a leader tip or in the large-scale field, is still worked on.

Claim 39 · checked 24 September 2026 · AI-assisted audit

Claim: by runaway processes of the kind Wilson suggested in the 1920s.

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Source checked. The cited passage was read, and it says this.

What this does not establish

Wilson's own paper was not read; this rests on how two later papers cite it. Crossref dates the volume 1924 and the papers cite 1925, so the page says "the 1920s".

Corrected

24 September 2026. Previously: “That means electrons inside thunderclouds are being accelerated to relativistic energies, which is not something anybody predicted from cloud physics.” Runaway electrons in thunderstorm fields were proposed by C. T. R. Wilson in the 1920s, as the later papers cited here record, so "not something anybody predicted" was wrong.

24 September 2026. Previously: “That means electrons inside thunderclouds are being accelerated to relativistic energies, by runaway processes of the kind C. T. R. Wilson suggested in the 1920s.” The saved texts of both citing papers name him only as "Wilson (1925)"; the initials came from a record that is not among the evidence, so they were taken out.

Claim 40 · checked 24 September 2026 · AI-assisted audit

How that was discovered

Claim: How that was discovered

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: The gamma-ray flashes were first reported in 1994, from a satellite instrument built to watch for cosmic gamma-ray bursts.

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Source checked. The cited passage was read, and it says this.

Corrected

24 September 2026. Previously: “The gamma-ray flashes were found in 1994 by a satellite instrument built to watch for cosmic gamma-ray bursts.” The discovery paper says the events were detected over the two years before; 1994 is when they were reported.

Claim 42 · checked 24 September 2026 · AI-assisted audit

Claim: The bursts it kept recording were coming from below it.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

  • Supports

    Discovery of Intense Gamma-Ray Flashes of Atmospheric Originabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Earth and its record · Observational study: associations, not causes

    The source reads: These flashes must originate in the atmosphere at altitudes above at least 30 kilometers in order to escape atmospheric absorption and reach the orbiting detectors.

What this does not establish

Read as an abstract.

Later work looked for

Crossref and Europe PMC, 1994 on, "terrestrial gamma-ray flash": every later instrument confirms the terrestrial origin; nothing that changes it.

Claim 43 · checked 24 September 2026 · AI-assisted audit

Claim: At least a dozen had been recorded in two years.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

  • Supports

    Discovery of Intense Gamma-Ray Flashes of Atmospheric Originabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Earth and its record · Observational study: associations, not causes

    The source reads: At least a dozen such events have been detected over the past 2 years.

What this does not establish

Read as an abstract.

Later work looked for

A historical count from the discovery paper; later catalogues are far larger and do not change what was recorded then.

Corrected

24 September 2026. Previously: “A dozen had been recorded in two years.” The paper says "at least a dozen".

Claim 44 · checked 24 September 2026 · AI-assisted audit

Claim: They were brief, they looked like bremsstrahlung from electrons at millions of electronvolts, and the discovery team placed the source above thirty kilometres, above the storms.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

  • Supports

    Discovery of Intense Gamma-Ray Flashes of Atmospheric Originabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Earth and its record · Observational study: associations, not causes

    The source reads: brief, intense flashes of gamma rays ... consistent with bremsstrahlung emission from energetic (million–electron volt) electrons ... a rare type of high-altitude electrical discharge above thunderstorm regions

  • Supports

    Discovery of Intense Gamma-Ray Flashes of Atmospheric Originabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Earth and its record · Observational study: associations, not causes

    The source reads: These flashes must originate in the atmosphere at altitudes above at least 30 kilometers

What this does not establish

Read as an abstract. The team called the high-altitude origin speculative.

Later work looked for

Crossref, 2005 on: Dwyer and Smith (2005) revise the altitude down, which the next paragraph reports.

Corrected

24 September 2026. Previously: “and the discovery team placed the source above thirty kilometres, higher than any storm.” The paper places the likely origin "above thunderstorm regions"; "higher than any storm" is not in it.

Claim 45 · checked 24 September 2026 · AI-assisted audit

Claim: Later spectra, fitted with simulations, brought it down to between fifteen and twenty-one kilometres, low enough to point at the thunderstorms themselves.

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

What this does not establish

A Monte Carlo fit to one instrument's summed spectrum, read as an abstract. The same paper found some of the discovery satellite's flashes too soft for that depth and allowed a second source above thirty kilometres.

Later work looked for

Europe PMC, 2010 on, "terrestrial gamma-ray flash": work with the ASIM instrument on the space station (Skeie and others 2022) ties the flashes to the early phase of intracloud lightning; the page now says so.

Corrected

24 September 2026. Previously: “Later spectra brought it down to between fifteen and twenty-one kilometres, which is inside a storm rather than above one,” The range comes from simulations fitted to a spectrum, and fifteen to twenty-one kilometres is at or above storm tops rather than inside a storm; the paper says the result points to thunderstorms rather than sprites.

Claim 46 · checked 24 September 2026 · AI-assisted audit

Claim: Radio measurements since suggest the flashes come early in lightning that stays inside the cloud.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

What this does not establish

A summary, in one 2022 paper, of earlier radio studies that were not read; the paper itself says the exact order of flash and optical pulse is still uncertain.

Later work looked for

Europe PMC, 2010 on, "terrestrial gamma-ray flash": work with the ASIM instrument on the space station (Skeie and others 2022) ties the flashes to the early phase of intracloud lightning; the page now says so.

Corrected

24 September 2026. Previously: “” Added: the currency search found that later work ties the flashes to the early phase of intracloud lightning.

Claim 47 · checked 24 September 2026 · AI-assisted audit

Claim: The gamma-ray burst monitor on the Fermi space telescope has recorded photons from them at around thirty million electronvolts.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

  • Supports

    First results on terrestrial gamma ray flashes from the Fermi Gamma-ray Burst Monitorabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Earth and its record · Measurement

    The source reads: The Gamma‐ray Burst Monitor (GBM) on the Fermi Gamma‐ray Space Telescope detected 12 intense terrestrial gamma ray flashes ... Typical maximum energies for most of the TGFs are ∼30 MeV, with one TGF having a 38 MeV photon

What this does not establish

Twelve flashes in the instrument's first year, read as an abstract.

Later work looked for

Europe PMC, 2010 on: Skeie and others (2022) give individual photon energies "up to ∼40 MeV"; consistent, nothing that changes it.

Corrected

24 September 2026. Previously: “and a space telescope built to catch gamma-ray bursts has since recorded photons from these flashes at around thirty million electronvolts.” The burst monitor is one instrument on a telescope with a wider purpose; the page now names it.

Claim 48 · checked 24 September 2026 · AI-assisted audit

Claim: The discovery paper called them "an unexplained terrestrial phenomenon".

Kind
Quotes a source. The words of a named text, checked against the source.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

  • Supports

    Discovery of Intense Gamma-Ray Flashes of Atmospheric Originabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Earth and its record · Observational study: associations, not causes

    The source reads: Detectors aboard the Compton Gamma Ray Observatory have observed an unexplained terrestrial phenomenon: brief, intense flashes of gamma rays.

What this does not establish

Read as an abstract; the quotation is from it.

Corrected

24 September 2026. Previously: “Nothing in atmospheric physics predicted them.” Runaway electrons in thunderstorms had been proposed since the 1920s, so "nothing predicted them" overstated it. The discovery paper's own word was "unexplained".

Claim 49 · checked 24 September 2026 · AI-assisted audit

Claim: They were found by an instrument watching the whole sky for something else,

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    The Burst And Transient Source Experiment (BATSE)instrument page

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: serves as the all-sky monitor for the Compton Observatory, detecting and locating strong transient sources called gamma-ray bursts as well as outbursts from other sources over the entire sky

Corrected

24 September 2026. Previously: “They were an accident of pointing an instrument at the sky and noticing what arrived from the wrong direction.” The instrument was an all-sky monitor, not one pointed at the sky; "accident" is not in any source.

Claim 50 · checked 24 September 2026 · AI-assisted audit

Claim: which noticed what arrived from the wrong direction.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

The instrument watched the sky and the flashes came from the Earth below it.

Claim 51 · checked 24 September 2026 · AI-assisted audit

How it begins

Claim: How it begins

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: Forty-four times a second, worldwide,

Kind
Present-day figure. A count, survey or report finding, as the named source gives it.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

What this does not establish

Read as an abstract; the figure is 44 ± 5.

Later work looked for

As for claim 4: the 2014 and 2026 climatologies give no different global rate in the abstracts read.

Corrected

24 September 2026. Previously: “Forty times a second, worldwide, by a mechanism that has not been identified.” "Forty" had no source and contradicted the subtitle. The satellite count is 44 ± 5. And the initiating mechanism has been identified by one group (claim 60) and disputed, which "not identified" did not say.

Claim 53 · checked 24 September 2026 · AI-assisted audit

Claim: by a mechanism still argued over.

Kind
Disputed. A contested point, where the page reports a side or the disagreement.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

  • Context

    Observations of narrow bipolar events reveal how lightning is initiated in thunderstormsabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Observational study: associations, not causes

    The source reads: The observations show that many or possibly all lightning flashes are initiated by fast positive breakdown.

  • Context

    Fast negative breakdown in thunderstormsabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Observational study: associations, not causes

    The source reads: that does not fit with our current understanding of dielectric breakdown

Other readings

Rison and colleagues say their observations show how lightning starts; Dwyer's runaway mechanism and the later fast negative breakdown are the other positions the page reports.

Claim 54 · checked 24 September 2026 · AI-assisted audit

What initiates it

Claim: What initiates it

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: The fields measured inside thunderclouds are lower than most of the proposed mechanisms require.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

  • Supports

    The initiation of lightning by runaway air breakdownabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · A simulation · Model

    The source reads: The ambient electric field strength needed for this mechanism is within the range of values observed in thunderclouds and is substantially lower than that required by most other mechanisms.

  • Supports

    A brief review of the problem of lightning initiation and a hypothesis of initial lightning leader formationabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Earth and its record · Review of the field

    The source reads: The historically favored positive streamer mechanisms are problematic due to requiring electric fields two to three times larger than peak observed fields.

  • Supports

    Observations of narrow bipolar events reveal how lightning is initiated in thunderstormsDiscussion

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Observational study: associations, not causes

    The source reads: For hydrometeor-initiated streamers, the required field strength is estimated by Petersen et al. ... to be at least a factor of two greater than the largest electric fields observed in storms

What this does not establish

Dwyer and Petersen were read as abstracts; Rison in full. "Most" is Dwyer's word, and the mechanism he proposes is one of the few said to work at observed fields. Compact regions of strong field could exist that in situ instruments have missed, as Rison and colleagues note.

Later work looked for

Europe PMC, 2016 on, "lightning initiation": Tilles and others (2019) still describe measured fields as well below the breakdown threshold; nothing that changes it.

Claim 56 · checked 24 September 2026 · AI-assisted audit

Claim: Something must locally exceed the threshold or lower it.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

Follows from claim 56: if the measured field is too weak, the start needs a local exception. Both sources frame the problem that way.

Claim 57 · checked 24 September 2026 · AI-assisted audit

Claim: The leading proposals are that water drops and ice particles concentrate the field at their surfaces, or that the steady background of cosmic rays seeds an avalanche of high-energy electrons that runs away and amplifies the field until conventional breakdown can happen.

Kind
Hypothesis. A proposed explanation, not an established one.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

  • Supports

    A brief review of the problem of lightning initiation and a hypothesis of initial lightning leader formationabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Earth and its record · Review of the field

    The source reads: Various mechanisms have been proposed to explain how lightning can initiate in such weak electric fields, including hydrometeor‐initiated positive streamers and cosmic ray‐initiated runaway breakdown.

  • Supports

    The initiation of lightning by runaway air breakdownabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · A simulation · Model

    The source reads: this mechanism uses the runaway electrons produced by the steady background of atmospheric cosmic‐rays to amplify non‐uniformities in the electric field ... enhancing the electric field in front of it to the point where a conventional breakdown can occur

  • Supports

    Observations of narrow bipolar events reveal how lightning is initiated in thunderstormsDiscussion

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Observational study: associations, not causes

    The source reads: The streamers would be initiated by corona from ice crystals or liquid hydrometeors ... The most promising mechanism has been that proposed by Dwyer

What this does not establish

Dwyer's mechanism is a simulation, read as an abstract. Petersen and others argue neither is enough alone and propose a hybrid of the two.

Claim 58 · checked 24 September 2026 · AI-assisted audit

Claim: They are not equally supported.

Kind
Disputed. A contested point, where the page reports a side or the disagreement.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

Other readings

This is the reading of the interferometry group, and the page reports it as theirs. The runaway mechanism was proposed as working at the fields actually measured (claim 58), and Petersen and others argue for a hybrid of the two.

Claim 59 · checked 24 September 2026 · AI-assisted audit

Claim: Interferometry of the first microseconds of a flash finds a burst of fast positive breakdown that looks like streamers started by corona on ice crystals or drops, and the same group reports little or no evidence that electron avalanches are involved at all.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

What this does not establish

Three high-power events in one New Mexico storm studied closely, with precursor statistics from others; "many or possibly all" flashes is the authors' extension.

Claim 60 · checked 24 September 2026 · AI-assisted audit

Claim: A follow-up in Florida by several of the same researchers, with an improved interferometer, found fast breakdown that can also begin with negative polarity, which its authors say does not fit current understanding of how air breaks down.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Fast negative breakdown in thunderstormsabstract; Introduction

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Observational study: associations, not causes

    The source reads: confirms that electrical breakdown in thunderstorms can begin with oppositely-directed fast breakdown of negative polarity ... that does not fit with our current understanding of dielectric breakdown ... we deployed an improved version of the broadband VHF radio interferometer used by Rison et al. ... to Kennedy Space Center in Florida

What this does not establish

A small number of events in Florida storms. The authors consider but do not settle whether the negative breakdown is a retrograde form of positive streamers.

Later work looked for

Europe PMC, 2016 on, "lightning initiation": this is the newer work the search found; added to the page.

Corrected

24 September 2026. Previously: “” Added: the currency search found a 2019 result from the same instrument group that complicates the positive-breakdown account the page leaned on.

Claim 61 · checked 24 September 2026 · AI-assisted audit

Claim: Neither account is settled,

Kind
Open question. Something the page says is not known.
Review
Presented as open. The page says this is unresolved, and the review found that it is.

  • Supports

    Fast negative breakdown in thunderstormsDiscussion, summary

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Observational study: associations, not causes

    The source reads: It is unclear what physical mechanism is behind the fast negative breakdown

Claim 62 · checked 24 September 2026 · AI-assisted audit

Claim: and the measurement that would settle it has to be made inside a thundercloud.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

The disputed quantity is the local field where a flash starts, which only an instrument in the cloud can measure directly.

Claim 63 · checked 24 September 2026 · AI-assisted audit

How the cloud charges in the first place

Claim: How the cloud charges in the first place

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: The charge comes from collisions.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Understanding Lightning ScienceHow Thunderstorms Develop

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: Air movements and collisions between the various types of precipitation in the middle of the cloud cause the precipitation particles to become charged.

  • Supports

    Relationship between lightning and ice hydrometeors in thunderstorms over northern India from polarimetric weather radar observationsIntroduction

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Observational study: associations, not causes

    The source reads: The most accepted charging mechanism of thunderclouds is the non-inductive charging mechanism, which basically involves charge separation during rebounding collisions between graupel and ice-crystals.

What this does not establish

"Most accepted" is the field's standing as one paper states it; an inductive mechanism, also acting through collisions, is described as well.

Later work looked for

NOAA's page and a 2026 study (Jash and others) give the same collision mechanism as the most accepted; nothing that changes it.

Claim 65 · checked 24 September 2026 · AI-assisted audit

Claim: A developed thundercloud carries ice crystals in its upper levels and a mixture of ice and small hail in the middle, and collisions between them in the rising air leave the lighter ice crystals positively charged and carried upward while the heavier hail takes the negative charge and is held up by the rising air or falls.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Understanding Lightning ScienceHow Thunderstorms Develop

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: A well-developed thunderstorm cloud contains mostly small ice crystals in the upper levels of the cloud, a mixture of small ice crystals and small hail in the middle levels of the cloud ... The lighter ice crystals become positively charged and are carried upward into the upper part of the storm by rising air. The heavier hail becomes negatively charged and is either suspended by the rising air or falls toward the lower part of the storm.

What this does not establish

The usual case: the sign can reverse with temperature and water content, as claim 69 says.

Later work looked for

NOAA's page and a 2026 study (Jash and others) give the same collision mechanism as the most accepted; nothing that changes it.

Corrected

24 September 2026. Previously: “while the heavier hail takes the negative charge and stays low or falls.” The source says the hail is suspended by the rising air or falls, not that it stays low.

Claim 66 · checked 24 September 2026 · AI-assisted audit

Claim: That is what separates the top of the cloud from the bottom.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Understanding Lightning ScienceHow Thunderstorms Develop

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: These collisions and air movements cause the top of the thunderstorm cloud to become positively charged and the middle and lower part of the storm to become negatively charged.

Later work looked for

NOAA's page and a 2026 study (Jash and others) give the same collision mechanism as the most accepted; nothing that changes it.

Claim 67 · checked 24 September 2026 · AI-assisted audit

Claim: What decides which way the charge goes is still being worked out.

Kind
Open question. Something the page says is not known.
Review
Presented as open. The page says this is unresolved, and the review found that it is.

Corrected

24 September 2026. Previously: “What happens during a single one of those collisions, and what decides which way the charge goes, is not something this page has a source for.” A statement about the page rather than the world. A readable source now carries the open question.

Claim 68 · checked 24 September 2026 · AI-assisted audit

Claim: Laboratory experiments find that it depends on the temperature and on how much supercooled water the hail is collecting, and they disagree about where the sign reverses.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

What this does not establish

The laboratory studies themselves (Takahashi; Jayaratne and colleagues) were not read; this is how a 2026 paper summarises them. The "hail" here is graupel, soft hail grown by riming.

Later work looked for

Europe PMC, open access, "non-inductive charging": Medina and others (2021) summarise the same dependence on temperature and effective liquid water content; nothing that changes it.

Corrected

24 September 2026. Previously: “” Added: the sign dependence and the laboratory disagreement, which an earlier pass removed for want of a readable source, are carried by a 2026 open-access paper.

Claim 69 · checked 24 September 2026 · AI-assisted audit

What was read