1. The Nature of the Blast  Efficiency of explosion  Kind and shape of blasts  Blast effects, range & damage  Thermal effects  Radiation effects The results of the weapons test programs Blast—40-60% of total energy Thermal radiation—30-50% of total energy Ionizing radiation—5% of total energy Residual radiation (fallout)—5-10% of total energy

2. Classifications of blasts  Surface Blast: fireball in touch with surface vaporization of surface structures through blast and firestorm, immediate radioactive fallout  High Altitude Air Blast: fireball > 100,000 ft (>3000m) interrupts satellite based communication through electromagnetic pulse (EMP)  Low Altitude Air Blast: fireball < 100,000 ft (without touching ground) generates shock waves, pressure difference artificial for large areal damage, sea battle  Subsurface Blast: Underwater burst generates surge

3. Surface Blast – the fireball Central temperature: ~10,000,000 K Immediate vaporization of material! Central pressure:~33000 atm  Radiation release & absorption in surrounding matter generates red-glow intense luminosity.  Expansion of fireball through internal pressure  Fireball rises like hot air balloon Stokes August 1957 1500 Foot Balloon 19 kt

4. Fireball expansion Pressure evolution within the fireball: temperature pressure Sedov Taylor approximation (valid of first 0.1s) allowed Russians to estimate the power of the Trinity bomb from the expansion time conditions t r 0.1 ms24 m 0.4 ms42 m 0.7 ms52 m 0.9 ms60 m

5. Expansion speed Initial expansion speed v (T≈1,000,000 K) c s is the speed of sound in the vaporized gas  is the specific heat ratio of the gas R is the gas constant: 287 [J/kg K]; T is temperature [K] Cool-down to T≈3,000 after 15 ms due to radiation losses Ideal gas Fully ionized plasma

6. The shock front development After ~10 second the fireball expands with constant rate of ~300 ft/s After ~ 1minute fireball has cooled and radiation emission ceases!

7. 18 ms 16 ms 6ms90 ms 109 ms 15.0 s

8. Analysis of Fire ball Sedov-Taylor Blast analysis Valid as long as shock is super sonic: K≈1 Approximation allowed Russian scientists to estimate the power of US Trinity bomb.

9. Evolution of Mushroom cloud

10. General Features – the mushroom the emergence of the mushroom shape  Absorption of cool air triggers fast toroidal circulation of hot gases and causes upward motion forming the stem and mushroom.  Condensation of water changes red brownish color of cloud towards white!  Strong upward wind Drags dirt and debris Into the cloud mixing with radioactive material  Cloud rises in height with ~ 440 ft/s

11. Model

12. Dirt

13. Cloud Altitude Maximum altitude for cloud rise is reached after ~ 4min. RATE OF RISE OF THE RADIOACTIVE CLOUD FROM a I-MEGATON AIRBURST Height Time Rate of Rise (miles) (min) (mph) 2.0 0.3 330 3.0 40.7 270 4.0 61.1 220 5.0 102.5 140 6.0 123.8 27 Cloud height & cloud radius depend on the magnitude of the explosion, increase of both radius & height scales with explosion yield.

14. Chimney effect again! v=wind velocity in m/s g=9.8 m/s 2 earth acceleration H=height of heat column in [m] T o =outside temperature, K T i =inside temperature in K For typical firestorm: H ≈ 10,000 m T i ≈ 1,000,000 K T o ≈ 300 K ➱ v ≈ 288m/s = 647 miles/h Hurricane speeds ~100 miles/h Conventional firestorm ~220 miles/h