Atmos. Chem. Phys. Discuss., 11, 12649-12670, 2011
www.atmos-chem-phys-discuss.net/11/12649/2011/
doi:10.5194/acpd-11-12649-2011
© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Possible catalytic effects of ice particles on the production of NOx by lightning discharges
H. S. Peterson1 and W. H. Beasley2
1National Aeronautics and Space Administration, Marshall Space Flight Center, National Space Science and Technology Center, 320 Sparkman Drive, Huntsville, AL 35805, USA
2University of Oklahoma, School of Meteorology, 120 David L Boren Blvd Suite 5900, Norman, OK 73072, USA

Abstract. It is well known that lightning produces NOx as a result of the high temperatures in discharge channels. Since most viable proposed electrification mechanisms involve ice crystals, it is reasonable to assume that lightning discharge channels frequently pass through fields of ice particles of various kinds. We address the question of whether ice crystals may serve as catalysts for the production of NOx by lightning discharges. If so, and if the effect is large, it would need to be taken into account in estimates of global NOx production by lightning. In this study, we make a series of plausible assumptions about the temperature and concentration of reactant species in the environment of discharges and we postulate a mechanism by which ice crystals are able to adsorb nitrogen atoms. We then compare production rates between uncatalyzed and catalyzed reactions at 2000 K, 3000 K, and 4000 K, which are reasonable temperatures in lightning channels as they cool down. Catalyzed NO production rates are greater at 2000 K, whereas uncatalyzed production rates are greater at 4000 K. This effect may be relevant to the question of the relative importance of cloud-to-ground and in-cloud lightning for NOx production.

Citation: Peterson, H. S. and Beasley, W. H.: Possible catalytic effects of ice particles on the production of NOx by lightning discharges, Atmos. Chem. Phys. Discuss., 11, 12649-12670, doi:10.5194/acpd-11-12649-2011, 2011.
 
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