# Nuclear Fireball (DD-052) > A nuclear detonation heats the weapon's residues to several tens of millions of degrees. Within a millionth of a second they give off X-rays that the surrounding air absorbs within a few feet, forming the incandescent fireball. The fireball's rapid early expansion compresses the air into a blast wave. For a low-altitude fission burst, roughly 50% of the energy goes into blast, 35% into thermal radiation and 15% into nuclear radiation. - Department: Military (also Science) - First published: 2025-04-11 - Last updated: 2025-04-11 - Permalink: https://detailenjoyer.com/case/nuclear-fireball/ - Author: Marcus Easterling (DetailEnjoyer), The Detail Department ## Quick facts - **DD-052-F01**: A nuclear fireball's weapon residues reach several tens of millions of degrees. _(Write-up · Exhibit A (Hotter than the Reel says))_ - **DD-052-F02**: Roughly 50% blast, 35% thermal and 15% nuclear radiation for a low-altitude fission burst. _(Write-up · Exhibit D (Where the energy goes))_ ## Write-up The first seconds of a nuclear explosion. Temperatures reach tens of millions of degrees. 1. **Hotter than the Reel says**: Glasstone and Dolan put the maximum temperature of fission weapon residues at several tens of millions of degrees, similar to the center of the Sun. A conventional high explosive peaks at about 5,000 °C. The heat turns all the weapon's materials into gas, at pressures probably over a million times atmospheric. 2. **How the fireball forms**: Within less than a millionth of a second, the hot residues radiate energy mainly as invisible X-rays. The surrounding sea-level air absorbs them within a few feet, forming an extremely hot, luminous sphere of air and weapon gases. That sphere is the fireball. 3. **Growth, then the blast wave**: According to FM 8-9, a 1-megaton air burst's fireball is about 150 m across within a millisecond and reaches a maximum of about 2,200 m within 10 seconds while rising like a hot-air balloon. Its initial rapid expansion compresses the surrounding air, producing the blast wave. 4. **Where the energy goes**: As a rule of thumb, for a fission weapon burst below about 40,000 feet, about 50% of the energy goes into blast, 35% into thermal radiation and 15% into nuclear radiation. Of that 15%, about 5% is initial radiation within the first minute and 10% is residual radiation, mostly fallout. The split varies with yield, altitude and weapon design. 5. **The flash**: After about a millisecond, the fireball of a 1-megaton weapon would look many times brighter than the noon Sun to an observer 50 miles away. Its infrared component causes widespread burns and fires, at ranges that depend on yield. ## Related case files - [Atomic Annie (DD-004)](https://detailenjoyer.com/case/atomic-annie/): Another nuclear test: the 1953 Grable shot, the only nuclear artillery shell ever fired. - [Cherenkov Glow (DD-020)](https://detailenjoyer.com/case/cherenkov-glow/): A different nuclear glow: Cherenkov light from charged particles in water. - [The Beirut Blast (DD-266)](https://detailenjoyer.com/case/the-beirut-blast/): I linked another huge blast - [About to Blow (DD-267)](https://detailenjoyer.com/case/about-to-blow/): I linked another huge blast - [Kiloton (DD-270)](https://detailenjoyer.com/case/kiloton/): I linked more nuclear tests - [Nuclear Shadows (DD-330)](https://detailenjoyer.com/case/nuclear-shadows/): I linked more nuclear history - [Second Impact (DD-578)](https://detailenjoyer.com/case/second-impact/): Another enormous release of energy in seconds - [Cloud Chambers (DD-623)](https://detailenjoyer.com/case/cloud-chambers/): Another case about ionizing radiation - [Yonshakudama (DD-680)](https://detailenjoyer.com/case/yonshakudama/): Another giant burst in the sky - [Chicxulub Crater (DD-693)](https://detailenjoyer.com/case/chicxulub-crater/): Another case about an enormous release of energy ## Reel vs. record - **Temperature**: 'several million degrees' understates it. Glasstone and Dolan, and FM 8-9, give several tens of millions of degrees for the weapon residues at detonation. - **Omission**: the Reel covers heat and blast but leaves out nuclear radiation. Roughly 15% of the energy goes into it, about 5% as initial radiation and 10% as residual radiation, mostly fallout. - **Shock wave**: the blast wave comes from the fireball's initial rapid expansion compressing the air. The fireball then slows, reaching a maximum of about 2,200 m for 1 megaton within about 10 seconds, while the blast wave moves on ahead. - **Mechanism**: the fireball forms because X-rays from the weapon residues are absorbed within a few feet of air in under a millionth of a second, not simply because heat 'ionizes' the air. - **Note**: 'Miles away': burn ranges depend heavily on yield, burst height and conditions. The energy split itself varies with yield and altitude. ## Video: Nuclear Fireball: The First Seconds of a Nuclear Explosion - Duration: 28.8 s · Published: 2025-04-11 - File: https://detailenjoyer.com/assets/videos/DIT_gCARFZA.mp4 ### Transcript DID YOU KNOW? In the first seconds of a nuclear explosion a massive amount of energy is released almost instantaneously, creating a blinding flash of light and forming a rapidly expanding fireball that can reach temperatures of several million degrees Celsius. This intense heat vaporizes anything near the blast center, and causes surrounding air to ionize, forming a glowing plasma sphere. The fireball expands outward at supersonic speeds creating a powerful shockwave that flattens structures and emits intense thermal radiation capable of causing severe burns miles away. NOW YOU KNOW! ## Questions & answers **Q: Roughly how hot do a nuclear weapon's residues get at detonation?** A: Glasstone and Dolan give several tens of millions of degrees. _(Source: Write-up · Exhibit A (Hotter than the Reel says) · Glasstone and Dolan (1977), The Effects of Nuclear Weapons, Chapter II (Atomic Archive); US Army FM 8-9, Part I, Chapter 3: Effects of Nuclear Explosions (FAS))_ **Q: What does the surrounding air absorb to form the fireball?** A: X-rays from the residues are absorbed within a few feet of air. _(Source: Write-up · Exhibit B (How the fireball forms) · Glasstone and Dolan (1977), The Effects of Nuclear Weapons, Chapter II (Atomic Archive))_ **Q: About how much of a low-altitude fission burst's energy is thermal radiation?** A: The rule of thumb is about 35% thermal, 50% blast and 15% nuclear radiation. _(Source: Write-up · Exhibit D (Where the energy goes) · Glasstone and Dolan (1977), The Effects of Nuclear Weapons, Chapter I (Atomic Archive); US Army FM 8-9, Part I, Chapter 3: Effects of Nuclear Explosions (FAS))_ **Q: What produces the blast wave?** A: The fireball's rapid expansion compresses the surrounding air. _(Source: Write-up · Exhibit C (Growth, then the blast wave) · US Army FM 8-9, Part I, Chapter 3: Effects of Nuclear Explosions (FAS))_ **Q: Maximum fireball diameter for a 1-megaton air burst, per FM 8-9?** A: About 2,200 m, reached within about 10 seconds. _(Source: Write-up · Exhibit C (Growth, then the blast wave) · US Army FM 8-9, Part I, Chapter 3: Effects of Nuclear Explosions (FAS))_ ## Sources - [Glasstone and Dolan (1977), The Effects of Nuclear Weapons, Chapter I (Atomic Archive)](https://www.atomicarchive.com/resources/documents/effects/glasstone-dolan/chapter1.html) - [Glasstone and Dolan (1977), The Effects of Nuclear Weapons, Chapter II (Atomic Archive)](https://atomicarchive.com/resources/documents/effects/glasstone-dolan/chapter2.html) - [US Army FM 8-9, Part I, Chapter 3: Effects of Nuclear Explosions (FAS)](https://nuke.fas.org/guide/usa/doctrine/dod/fm8-9/1ch3.htm) ## Cite this case file Easterling, Marcus. "Nuclear Fireball." The Detail Department (DetailEnjoyer), case file DD-052, last updated Apr 11, 2025. https://detailenjoyer.com/case/nuclear-fireball/