1---2name: lightning3description: Comprehensive lightning physics knowledge base derived from Rakov & Uman (2003) "Lightning: Physics and Effects". Covers discharge types, current parameters, leader/return-stroke physics, cloud electrification, protection, detection systems, atmospheric effects, and quantitative reference data. Use when answering questions about lightning physics, electromagnetic fields, thunderstorm electricity, lightning protection, or atmospheric electrical phenomena.4license: MIT5---67# Lightning Physics Knowledge Base89Quantitative reference on lightning physics, effects, and protection. All data10from Rakov & Uman (2003) unless noted.1112## Reading Order1314| Task | File |15| ----------------------------------------------- | ------------------------------------------- |16| Lightning types, terminology, global circuit | `references/types-terminology-circuit.md` |17| Flash rates, density, geographic distribution | `references/incidence-statistics.md` |18| Thundercloud charge structure, electrification | `references/cloud-electrification.md` |19| Stepped leader physics | `references/stepped-leader.md` |20| Return stroke currents, speed, channel, fields | `references/return-stroke.md` |21| Dart leader, continuing current, M-components | `references/dart-leader-m-component.md` |22| Positive CG lightning and bipolar flashes | `references/positive-lightning.md` |23| Upward lightning from tall structures | `references/upward-lightning.md` |24| Rocket-triggered lightning | `references/triggered-lightning.md` |25| Cloud discharges and winter lightning | `references/cloud-winter-discharges.md` |26| Aircraft interaction and thunder | `references/aircraft-thunder.md` |27| Return stroke modeling (engineering + physical) | `references/return-stroke-models.md` |28| Sferics, Schumann resonances, whistlers | `references/distant-em-signals.md` |29| Sprites, elves, blue jets, TGFs | `references/upper-atmosphere-tles.md` |30| NOx production, extraterrestrial lightning | `references/chemistry-extraterrestrial.md` |31| Lightning locating systems (NLDN, satellite) | `references/locating-systems.md` |32| Protection methods, grounding, standards | `references/protection-standards.md` |33| Human hazards, safety, ball lightning | `references/human-hazards-unusual.md` |34| Cross-study statistical tables (Berger, Rakov) | `references/detailed-statistical-tables.md` |3536## Quick Reference: Key Parameters3738### Flash Structure3940| Parameter | Typical Value |41| ---------------------------- | ---------------- |42| Strokes per flash | 3-5 (range 1-26) |43| Flash duration | 200-300 ms |44| Interstroke interval | 60 ms |45| Total charge per flash | 20 C |46| Energy per flash | 10^9-10^10 J |47| Single-stroke flashes | 15-20% |48| Multiple ground terminations | ~50% of flashes |4950### Current Parameters (Berger et al. 1975)5152| Parameter | First Stroke (median) | Subsequent (median) |53| ----------------------------- | --------------------- | ------------------- |54| Peak current | 30 kA | 12 kA |55| Max dI/dt | 12 kA/us | 40 kA/us |56| Front duration (2 kA to peak) | 5.5 us | 1.1 us |57| Duration (to half-peak) | 75 us | 32 us |58| Impulse charge | 4.5 C | 0.95 C |59| Action integral | 5.5x10^4 A^2s | 6.0x10^3 A^2s |6061### Process Speeds6263| Process | Speed (m/s) |64| ---------------- | ----------------------- |65| Stepped leader | 2x10^5 (average) |66| Dart leader | 10^7 (typical) |67| Return stroke | (1-2)x10^8 (c/3 to c/2) |68| M-component wave | (2.5-3)x10^7 |6970### Channel Properties7172| Property | Value |73| ---------------- | ----------------------- |74| Peak temperature | 28,000-31,000 K |75| Peak pressure | ~8 atm (first 5 us) |76| Electron density | 8x10^17 cm^-3 (at 5 us) |77| Channel radius | 1-4 cm |78| Conductivity | ~10^4 S/m |7980### Lightning Types8182| Type | Fraction | Notes |83| -------------------- | ------------------- | -------------------------------------- |84| Downward negative CG | ~90% of CG | Most common |85| Downward positive CG | <10% of CG | Higher peak currents at extremes |86| Cloud discharges | ~75% of all | Intracloud, intercloud, cloud-to-air |87| Upward (neg + pos) | From >100 m objects | Only from tall structures/mountaintops |8889### Global Statistics9091| Quantity | Value |92| ------------------------------- | ------------------------------------------ |93| Global flash rate | 45 +/- 5 per second (satellite) |94| Cloud:CG ratio (z) | ~3 average (range 1-10+) |95| Land:ocean flash ratio | ~7.7 |96| Active thunderstorms (any time) | ~2000 |97| US annual CG flashes | ~25 million |98| US flash density range | 0.1 (Pacific) to >14 (Florida) km^-2 yr^-1 |99100### Positive Lightning Extremes101102| Parameter | 50% | 5% |103| --------------- | ------------- | ------------- |104| Peak current | 35 kA | 250 kA |105| Charge transfer | 80 C | 350 C |106| Action integral | 6.5x10^5 A^2s | 1.5x10^7 A^2s |107108## Computational Tools109110| Script | Contents |111| --------------------------------- | --------------------------------------------------------------------- |112| `scripts/leader_fields.py` | Stepped-leader E/B field (Eq 4.1-4.7), retarded height |113| `scripts/return_stroke_models.py` | Engineering models (TL/MTLL/MTLE/BG/TCS), Heidler, Braginskii |114| `scripts/thunder.py` | Few's theory (R_0, f_m), flash-to-bang, N-wave overpressure |115| `scripts/schumann.py` | Schumann resonance frequencies, whistler dispersion, Wait-Spies |116| `scripts/protection.py` | Striking distance, rolling sphere, grounding resistance, step voltage |117| `scripts/m_component.py` | M-component two-wave model (Eq 12.7-12.8), source pulse |118| `scripts/incidence.py` | Ng-Td/Th formulas, structure incidence, Poisson probability |119120All scripts use stdlib only (`math`, `enum`). Each has a `__main__` demo block.
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