Claim

Toronto's CN Tower receives several dozen lightning flashes per year.

Type QUANTITATIVE · truth-evaluable: yes · status at snapshot: ACTIVE · created seq 366

Referenced 148 times: checked 1, looked up by assistants 0, viewed 109, shared 38. A count of attention, not evidence.

Topics

Earth science · e554b29d

Assessment

Supported

Score: 0.9781 under ledger-default@0.3.0 at snapshot 27745

3 of 4 review checks done · 3 counted

2 independent evidence lineages · review checks 3 of 4 · stability HIGH

Main unresolved issue: 3 counted evidence items have no independence review; repeats of one origin may be counted as several coverage:d496a9d5-e7aa-8756-bf11-f7dc8f62d789

Not yet independently audited.Every quoted passage was confirmed on the page when Galedra fetched it.

Why?

Strongest counted support: Lightning researchers report that the 553 m CN Tower receives several dozen flashes per year while the surrounding Toronto ground flash density is about two per square kilometre per year, and attribute the concentration to field enhancement at a tall grounded structure's tip initiating upward leaders. weight 2.000000 evidence

Suppressed as dependent: The excerpt says the CN Tower usually receives several dozens of lightning flashes yearly.

Review gaps: independence reviewed

What would most change this: One independent, direct measurement that contradicts this claim would move it from Supported to Supported.

Hide calculation

0.9781 under ledger-default@0.3.0 at snapshot 27745 · state Supported · Review checks: 3 of 4 · stability HIGH · 3 sources, 2 independent lineages

Model ledger-default@0.3.0 (the default model, not the answer) · snapshot 27745 · trace sha256:82738b3f4678e419a1a2d1a5da984f571ec4c76374e47622a3c42e181820a761

Last changed at entry seq 11214; nothing logged since has borne on this claim.

How the number was reached

Each counted link is weighed by multiplying the factors the model declares; a factor it does not declare is not shown. Every factor name below links to what that number means.

Link	Working	Weight	Counted as
83a1010d support	relevance DIRECT 2.0 × observation MEASUREMENT 1.0 × interpretation 0 steps, 1 − 0.15 × 0 1.000000 × authenticity UNVERIFIED 1.0 × extraction UNVERIFIED 1.0 × provenance INDEPENDENT 1.0 × edition NAMED_OR_UNRELATED 1	2.000000	2.000000
ec172ff6 support	relevance DIRECT 2.0 × observation DIRECT_TEXT 0.9 × interpretation 0 steps, 1 − 0.15 × 0 1.000000 × authenticity UNVERIFIED 1.0 × extraction UNVERIFIED 1.0 × provenance INDEPENDENT 1.0 × edition NAMED_OR_UNRELATED 1	1.800000	1.800000
6a1b3f46 support	relevance DIRECT 2.0 × observation DIRECT_TEXT 0.9 × interpretation 0 steps, 1 − 0.15 × 0 1.000000 × authenticity UNVERIFIED 1.0 × extraction UNVERIFIED 1.0 × provenance INDEPENDENT 1.0 × edition NAMED_OR_UNRELATED 1	1.800000	0.000000 (dependent strongest only, kept 83a1010d)

prior 0.50 → log-odds 0.000000 + 3.800000 (the counted weights) = 3.800000 → probability 0.9781

Under neighbouring settings of the same model: 0.9346 to 0.9929, a spread of 0.0583.

Half-even rounding, six places for weights and four for the probability. The same inputs under the same model reproduce this exactly; that is what the trace hash above is for. How a score is worked out explains every factor, why it is there, and what the model sets it to.

Your view

Registered views

Nobody has registered a view yet.

Registered views are personal belief, not evidence: they never change Galedra's assessment. Affiliations are self-declared and shown only for groups of 5 or more.

Checked as part of

Statements this claim was broken out of. The claim is scored on its own; a statement's reading only counts its claims.

“Toronto's CN Tower receives several dozen lightning flashes per year.” · 1 claim · 28 September 2026

Evidence for

Lightning researchers report that the 553 m CN Tower receives several dozen flashes per year while the surrounding Toronto ground flash density is about two per square kilometre per year, and attribute the concentration to field enhancement at a tall grounded structure's tip initiating upward leaders.

From Luminosity Characteristics of CN Tower Lightning Flash Components (I. Sra, A. M. Hussein, P. Liatos, Ryerson University) Read 2026-09-18 Relevance DIRECT Steps 0 Counted
The excerpt says the CN Tower usually receives several dozens of lightning flashes yearly.

From Luminosity Characteristics of CN Tower Lightning Flash Components (I. Sra, A. M. Hussein, P. Liatos, Ryerson University) Read 2026-09-18 Relevance DIRECT Steps 0 Counted
The University of Toronto reports that the CN Tower is struck by lightning an average of 75 times per year.

From “Shocking” Research May Help Protect Technology Read 2026-09-28 Relevance DIRECT Steps 0 Counted

Independent university source directly supports the claim's broader “several dozen” wording.

Evidence against

None.

Qualifications

None.

Suppressed as dependent

Evidence	Group	Kept instead
532218c6		83a1010d

Inferences

Concluded from

None.

Used as a premise in

None.

An inference is interpretation, not evidence: it never changes the assessment of its conclusion. Each premise is a claim with its own evidence.

Threads

None. Threads are for disagreements about how a determination was made — a statement whose figures are not in the passage it rests on, two sources that may share an origin. Something about the world belongs in the evidence above.

Claim edges

None. Edges are stored and displayed; v0.1 does not propagate probability across them.

Review checklist

Review checks: 3 of 4

Check	Done	By
qualifiers reviewed	yes	e7a36f36
opposing search done	yes	51f386be
independence reviewed	no
primary source reviewed	yes	ec172ff6

Summary

Supported. The main support is: Lightning researchers report that the 553 m CN Tower receives several dozen flashes per year while the surrounding Toronto ground flash density is about two per square kilometre per year, and attribute the concentration to field enhancement at a tall grounded structure's tip initiating upward leaders. 61c096cd

1 further item repeats the same origin and is not independent evidence. 532218c6

A search for evidence in the opposing direction found none. 51f386be

Review checks: 3 of 4. coverage:d496a9d5-e7aa-8756-bf11-f7dc8f62d789

Generated by stub-v0.1; every sentence cites graph ids.

Contribution history

seq	event	detail
366	APPENDED
367	ACCEPT	AUTOMATIC_AFTER_VALIDATION
400	LINK_EVIDENCE	by e554b29d (accepted)
8828	TASK_RESULT	by 1efd24fe (accepted)
11213	LINK_EVIDENCE	by 1efd24fe (accepted)

Score trace

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  "claim": "d496a9d5-e7aa-8756-bf11-f7dc8f62d789",
  "links": [
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      "group": null,
      "reason": "dependent_strongest_only",
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  "model": "ledger-default@0.3.0",
  "prior": "0.50",
  "variants": {
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  "code_hash": "sha256:c61a6fdf35a754a0d7e958df149036a083c0eaeb7d2d2e52704ec32b0c36def7",
  "contested": false,
  "stability": "HIGH",
  "claim_type": "QUANTITATIVE",
  "config_hash": "sha256:86768038080b8ab5233f1e4b7aba10af05b5bb44caa432095150b90e81209809",
  "probability": "0.9781",
  "provisional": true,
  "evidence_sum": "3.800000",
  "snapshot_seq": 11214,
  "prior_log_odds": "0.000000",
  "support_groups": 2,
  "model_dependent": false,
  "review_coverage": "0.75",
  "truth_evaluable": true,
  "assessment_state": "SUPPORTED",
  "review_checklist": {
    "qualifiers_reviewed": {
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    "opposing_search_done": {
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    "independence_reviewed": {
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      "ok": false
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    "primary_source_reviewed": {
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  "contradict_groups": 0,
  "rounding_boundary": false,
  "posterior_log_odds": "3.800000",
  "not_applicable_reason": null,
  "independence_unreviewed": 3
}