Quote:
Originally Posted by Raellus
*Assuming most tactical strikes are air-bursts, the apparent damage attributable to a nuclear weapon might be much less obvious. After a year or two, damage from a low-yield airburst would probably be indistinguishable from that left behind by heavy conventional fighting, and radiation in the area could be negligible. How would a PC be able to differentiate between the two potential causes of damage, nuclear or conventional, to a given area? If damage was created by a low-yield nuclear airburst, what clues to its actual nature would there be?
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Just read this and wanted to share some thoughts.
You're correct that most tactical strikes would be air bursts. With (reactivated) B57 and the (almost ubiquitous) B61 probably delivering most of the strikes during the Twilight War. Nuclear bunker busters, such as the B83 nuclear bomb, which could also be dialed into the small kiloton range, would instead be used in ground burst or even subterranean explosions.
For explosions in these low kiloton and up to mid-double digit kiloton ranges, there are some important differences to keep in mind to the much bigger, strategic device explosions: First and foremost, their fireballs do not reach into the stratosphere, making them irrelevant for any discussions on the "nuclear winter" topic as this phenomenon is caused by black soot reaching the stratosphere in relevant amounts to have long lasting effects. Everything not reaching the stratosphere and thus remaining in the troposphere will fall back down onto the surface quickly, within hours or days, and thus have a negligible effect on climate (but not weather, an important difference!).
Second, even though we're talking tactical devices, these explosions are huge and extremely pinpointed. A 20 kt device will leave a crater 25 m deep, 15 m for a 5 kt device and still 6 m deep for the lowest possible yield a B61 can be dialed upon: 0.3 kt. These are no values conventional devices could attain, maybe with the exception of the Mk. 118 demolition bomb. The massive difference of nuclear bombs stems from the high pressure (psi) values reached, I believe, and not so much purely from the blast yield in tons TNT equivalent.
Third, the mode of why craters are formed is different, I believe. A nuclear device produces enormous levels of pressure (psi) an simulations from this
site suggest that crater depth does not depend on whether a burst occurs on the surface or in the air. Conventional, "dumb" bombs however tend to explode after hitting the surface and thus in the ground. This changes crater creation dynamics and the amount of matter ejected out of the crater: I would presume a nuclear airburst crater to have a wider crater lip radius (from the center to the outer boundary of the lip) due to the explosion ejecting matter outward to the sides. A conventional explosion might eject matter more into the air as well.
This latter point, the blast wave going to all sides, is what creates the immense pressure waves that destroy the surrounding area. A 0.3 kt blast, still being ca. 335 times larger than a that of a Mark 118 demolition bomb (with its 896 kg warhead) will result in moderate blast damage out to about 300 m to 340 m (depending on air burst optimization (radii or overpressure). Moderate blast damage here means 5 psi overpressure, most residential buildings collapse, injuries being universal, and fatalities being widespread. Light damage, including shattering glass and probably broken off trees, would go out to 1.32 km.
So, the main differences visible to the naked eye between a nuclear and a conventional explosion would simply be the massive damage to the surrounding environment far beyond the immediate crater. When the Saudis used a Mk. 87 bomb on a Yemeni market in March 2016 (with a 428 kg warhead filling) they killed 97 people. Hitting a market in an urban center with a 0.3 kt device would likely kill close to 6,000 people immediately and wound another 20,500 people, many of them would die from maiming and 3rd to 2nd degree burns, which occur out to about 380 m and 480 m respectively. These burns would be also visible on trees, with charring marks at least out to 350 m, but probably more, and knocked over trees out to beyond 1 km in a concentric pattern around the 6.18 m deep crater (that's easily a two story building).