Lightning Physics Knowledge Base

Quantitative reference on lightning physics, effects, and protection. All data from Rakov & Uman (2003) unless noted.

Reading Order

| Task | File | | ----------------------------------------------- | ------------------------------------------- | | Lightning types, terminology, global circuit | references/types-terminology-circuit.md | | Flash rates, density, geographic distribution | references/incidence-statistics.md | | Thundercloud charge structure, electrification | references/cloud-electrification.md | | Stepped leader physics | references/stepped-leader.md | | Return stroke currents, speed, channel, fields | references/return-stroke.md | | Dart leader, continuing current, M-components | references/dart-leader-m-component.md | | Positive CG lightning and bipolar flashes | references/positive-lightning.md | | Upward lightning from tall structures | references/upward-lightning.md | | Rocket-triggered lightning | references/triggered-lightning.md | | Cloud discharges and winter lightning | references/cloud-winter-discharges.md | | Aircraft interaction and thunder | references/aircraft-thunder.md | | Return stroke modeling (engineering + physical) | references/return-stroke-models.md | | Sferics, Schumann resonances, whistlers | references/distant-em-signals.md | | Sprites, elves, blue jets, TGFs | references/upper-atmosphere-tles.md | | NOx production, extraterrestrial lightning | references/chemistry-extraterrestrial.md | | Lightning locating systems (NLDN, satellite) | references/locating-systems.md | | Protection methods, grounding, standards | references/protection-standards.md | | Human hazards, safety, ball lightning | references/human-hazards-unusual.md | | Cross-study statistical tables (Berger, Rakov) | references/detailed-statistical-tables.md |

Quick Reference: Key Parameters

Flash Structure

| Parameter | Typical Value | | ---------------------------- | ---------------- | | Strokes per flash | 3-5 (range 1-26) | | Flash duration | 200-300 ms | | Interstroke interval | 60 ms | | Total charge per flash | 20 C | | Energy per flash | 10^9-10^10 J | | Single-stroke flashes | 15-20% | | Multiple ground terminations | ~50% of flashes |

Current Parameters (Berger et al. 1975)

| Parameter | First Stroke (median) | Subsequent (median) | | ----------------------------- | --------------------- | ------------------- | | Peak current | 30 kA | 12 kA | | Max dI/dt | 12 kA/us | 40 kA/us | | Front duration (2 kA to peak) | 5.5 us | 1.1 us | | Duration (to half-peak) | 75 us | 32 us | | Impulse charge | 4.5 C | 0.95 C | | Action integral | 5.5x10^4 A^2s | 6.0x10^3 A^2s |

Process Speeds

| Process | Speed (m/s) | | ---------------- | ----------------------- | | Stepped leader | 2x10^5 (average) | | Dart leader | 10^7 (typical) | | Return stroke | (1-2)x10^8 (c/3 to c/2) | | M-component wave | (2.5-3)x10^7 |

Channel Properties

| Property | Value | | ---------------- | ----------------------- | | Peak temperature | 28,000-31,000 K | | Peak pressure | ~8 atm (first 5 us) | | Electron density | 8x10^17 cm^-3 (at 5 us) | | Channel radius | 1-4 cm | | Conductivity | ~10^4 S/m |

Lightning Types

| Type | Fraction | Notes | | -------------------- | ------------------- | -------------------------------------- | | Downward negative CG | ~90% of CG | Most common | | Downward positive CG | <10% of CG | Higher peak currents at extremes | | Cloud discharges | ~75% of all | Intracloud, intercloud, cloud-to-air | | Upward (neg + pos) | From >100 m objects | Only from tall structures/mountaintops |

Global Statistics

| Quantity | Value | | ------------------------------- | ------------------------------------------ | | Global flash rate | 45 +/- 5 per second (satellite) | | Cloud:CG ratio (z) | ~3 average (range 1-10+) | | Land:ocean flash ratio | ~7.7 | | Active thunderstorms (any time) | ~2000 | | US annual CG flashes | ~25 million | | US flash density range | 0.1 (Pacific) to >14 (Florida) km^-2 yr^-1 |

Positive Lightning Extremes

| Parameter | 50% | 5% | | --------------- | ------------- | ------------- | | Peak current | 35 kA | 250 kA | | Charge transfer | 80 C | 350 C | | Action integral | 6.5x10^5 A^2s | 1.5x10^7 A^2s |

Computational Tools

| Script | Contents | | --------------------------------- | --------------------------------------------------------------------- | | scripts/leader_fields.py | Stepped-leader E/B field (Eq 4.1-4.7), retarded height | | scripts/return_stroke_models.py | Engineering models (TL/MTLL/MTLE/BG/TCS), Heidler, Braginskii | | scripts/thunder.py | Few's theory (R_0, f_m), flash-to-bang, N-wave overpressure | | scripts/schumann.py | Schumann resonance frequencies, whistler dispersion, Wait-Spies | | scripts/protection.py | Striking distance, rolling sphere, grounding resistance, step voltage | | scripts/m_component.py | M-component two-wave model (Eq 12.7-12.8), source pulse | | scripts/incidence.py | Ng-Td/Th formulas, structure incidence, Poisson probability |

All scripts use stdlib only (math, enum). Each has a __main__ demo block.