Saturday, December 17, 2011

Photography of Nuclear Detonations - High Speed - Nuclear Explosion Induced Lightning



"This is an old Lookout Mountain Labs production which highlights some EG&G films of US nuclear weapons testing in Nevada and the Pacific during the 1950s.. Of special note are two views of the CASTLE BRAVO shot (I think) which show nuclear explosion induced lightning effects. Originally hosted on an MIT server. Color (cruddy). Length: ~11:33. Unrestored. Year unknown (probably mid to late 1950s). No sound. Not classified."

I have never heard of nuclear lightning, but there is some great footage in this video that is new to me, including what is clearly lighting around the early fireball of test shot Ivy Mike. (At that time, it was by far the largest explosion ever.) Here is information about this lightning phenomenon:

"We report the results of a unique study of the lightning like phenomena that were seen to accompany the MIKE shot of operation IVY on October 31 1952. MIKE was a thermonuclear surface burst yielding 10.4 MT, which took place on Enewetak Atoll. During the period of approximately 10 ms after detonation, five discrete luminous channels were seen to start from the ground or sea surface at a distance of approximately 1 km from the burst point and to grow up into the clouds. We have reexamined the original photographic records of IVY-MIKE, obtaining effective brightnesses (optical powers per unit length) for the luminous channels at different altitudes as functions of time. The absolute calibration for the MIKE records was deduced by comparison with the photographic records of other events of that era, laboratory measurements of film sensitivity, and use of atmospheric transmission data taken just prior to the MIKE event. Errors in this analysis lead to an uncertainty of a factor of ~2 in the brightnesses of the luminous channels. In the laboratory we have used laser-guided electric discharges to create long (100 cm), arclike plasma channels to simulate the observed luminous channels and to allow determination of an empirical relation between the brightness of the channel and the electric current flowing in the channel.

These laboratory discharges had peak currents up to 100 kA and periods of ~2 ms. Spectroscopic analysis showed that the luminous channels consisted primarily of normal air plasma with typical ground-level contaminants. Photographic studies showed that these long-duration discharges are unstable to the m=1 magnetohydrodynamic (MHD) instability and become severely distorted in less than 1 ms. By direct comparison of the luminous channels seen at MIKE and the laboratory discharges, we deduce:(1) the peak current in the prominent (brightest) channel at MIKE was between 200 and 600 kA. Here the most likely value of the peak current was 250+/-50 kA, but potential systematic errors in the film calibration and the comparison of MIKE and laboratory data make higher currents possible. (2) The rapid decline in the brightness of the luminous channels seen at MIKE is caused by a combination of the effects of the MHD instability, which eventually leads to a broadening of the current-carrying channel, and channel cooling by turbulent convective mixing."

An empirical study of the nuclear explosion-induced lightning seen on IVY-MIKE - Journal of Geophysical Research, Volume 92, Issue D5, p. 5696-5712 - Colvin et. al.




Lots more information on nuclear tests found here:

http://glasstone.blogspot.com/

I cannot confirm, and honestly do not agree with many of the points in this blog. Like a certain aerospace blog, I find the posts very useful even if they are mixed evenly with a political agenda. To their credit, the agenda is never really denied. The author goes to great lengths to explain why the damage cased by nuclear blasts is actually minimal compared to what we have all come to expect from the media, government, liberals, or whomever. From years of research, I have found that sometimes the popular perception overstates the damage caused in a nuclear war, and sometimes the military and government underestimate it instead. Most interesting is the statement that attacks on urban areas would not result in a firestorm as in Hiroshima. I feel this ignores the amount of oil, natural gas, various other flammable liquids, and paper in an urban environment. Clearly a city-wide firestorm is unlikely. How could a fire spread across the hundreds of square km of a city like New York? But widespread fires of somewhat smaller-scale (yet still hugely damaging) would occur. Direct attacks on New York City would certainly damage and probably ignite the refinery oil-in system across the river in New Jersey, and possibly tankers in queue there. These fires wont kill many people, but they will have important ecological and climatological impacts.

I shudder to imagine the impact of a 100 kt attack on the Jamnagar Refinery in India, the largest in the World. Not only is such an attack more likely, due to well known problems with Pakistan, now on the verge of being taken over by Islamic terrorists, but it is also the kind of "local exchange" or "regional nuclear exchange" that can have global repercussions in climate. Cities in India are much closer to Hiroshima of 1945 than one would hope, and they are still candidates for widespread fire of very dirty fuels such as wood, coal, textiles, various oils and flammable liquids, and paper. The amount of smoke and ash created in a "local" war (with perhaps 25 detonations from each party) is staggering. There would be millions of kg of dust and ash produced as a result, not to mention fine soot particles that can be lofted into the upper atmosphere with larger detonations. I won't even get into the nitrogen oxides and ozone.

Going back to World War III, the risk of firestorm is a minor concern because a full-scale attack on a large city would physically destroy most of the city with between 3 and 15 warheads of 200 - 900 kt yield, in the instance of New York or Chicago. Not only would most buildings be damaged directly (all structures being exposed to at least one 200 kt blast at a distance of only a mile or two, followed by other blasts at greater distance) but the amount of fallout that is likely to occur after such a disaster will indeed render the urban area fatal to anyone who remains above-ground for days at the least. There is simply no way to deny this, and one can assume that anyone who has not escaped the city before or just after the blast, or who is not indoors (with intact windows and a supply of water) or underground will eventually die as a result of radiation exposure. Remember also that there will be no medical care, so LD/50 exposures will be bumped up to mostly fatal.

This is a complex topic and there are many different factors to consider. In reaction to the claim that nuclear weapons are not as deadly for civilians as expected, and are mostly a military weapon designed to target strategic forces of the enemy, I have to disagree. Nuclear weapons always have been and always will be a credible threat to civilians. Nuclear weapon strategy will never again work as a counter-force only strategy (even if, for a short time, it did.) It does little good to deny the fact that nuclear weapons are designed to kill as many civilians as possible, and in that they achieve the primary purpose of any large scale war; to destroy the social and economic structure of an enemy. Nuclear weapons achieve this in a simple way; by killing a vast number of individuals and destroying the infrastructure of their society. There is no reason to doubt the fact that a carefully executed nuclear strike would achieve this goal.

1 comment:

kanishks grank said...

Good information,Thanks for sharing.
Blast Induced Vibration Analysis