The Atmosphere After a Nuclear War Twilight at Noon

Previous investigations of the atmospheric effects following a nuclear war have been concentrated primarily on the expected large depletions of ozone in the stratosphere [1, 2]. Reduction of the stratospheric ozone shield allows increased levels of harmful ultraviolet (uv) radiation to penetrate to the surface of the earth. 

Cmtzen and H.G. Branch (eds.), Paul J. Crutzen A Pioneer on Atmospheric Chemistry and Climate Change in the Anthropocene, Nobel Laureates 50, DOI 10.1007/978-3-319-27460-7 5 

As assumed in Ambio s reference scenario, it is now believed that the most likely nuclear war is one in which few weapons having yields greater than 1 Mt are used, with preference given to the detonation of large numbers of smaller yield weapons. For such a nuclear war, very htde NOx would be injected above 15 km into the stratosphere by the nuclear birrsts, and thus depletion of the ozone layer would not occur as a direct result of the explosions. Nonetheless, other profound effects on the atmosphere can be expected. 

The explosion of nuclear weapons produces oxides of nitrogen by heating air to temperatures well above 2000 K. When the major constituents of the air—nitrogen and oxygen—are heated to high temperature, nitric oxide (NO) is formed. The equilibrium between N2, O2 and NO is rapidly approached at the temperatures characteristic of the nuclear explosions  

As the temperature of the heated air falls, the reactions which maintain equilibrium become slow and NO cannot revert to the innocuous oxygen and nitrogen. Consequently, nuclear explosions produce NO in much the same way as it is formed as a pollutant in automobile and aircraft engines. A review of the mechanisms forming NO in nuclear explosions is provided in Appendix 1. The oxides of 

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Crutzen and Birks (1982) The atmosphere after a nuclear war Twilight at noon, Ambio, 115-25. 

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