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Simulation of trace species production by lightning and corona discharge in moist air
SIMULATION OF TRACE SPECIES PRODUCTION BY LIGHTNING AND CORONA DISCHARGE IN MOIST AIR M. N. BHETANABHOTLA, B. A. CROWELL, A. COWOUVINOS, R. D. HILL and R. G. RINKER Department of Chemical and Nuclear Engineering, University of California, Santa Barbara, CA 93106. U.S.A. (First
received 5 November
1984; in revisedform
21 December 1984 and receivedfor 1985)
publication 4 February
Abstract-Numerical simulations of chemical processes initiated in moist air by lightning strokes and lightning coronas indite that the amounts of major new species generated are not very different from the amounts previously found in dry air. Thus, the major new species produced globally in moist air are estimated to be: 2.4 megatonnes NO y-t, 0.28 megatonnes NOa y-l and 220 tonnes NaO y- ‘. The minor species, ozone and those containing hydrogen released by lightning from water in moist air are: 1.2 kilotonnes C&Y;*~?,S kilotonnes HNOz y-t, 1.2 kilotonnes HNOJ y-t, 0.32 kilotonnes Hr02 y-’ and 0.32 kilotonnes 2 Key word index: ~i~tning
chemistry, corona chemistry, nitrogen fixation, wet air chemistry,
I.INTRODUCTION
Calculations of the production of trace species in the atmosphere by electrical and chemical processes initiated by fightning have been reported by Zipf and Dubin (1976), Tuck (1976), Chameides et al. (1977), Griffing (1977), Hill etal.(1978) and others. The abovenamed calculations were initiated in dry air. Two subsequent calculations employed more realistic atmospheres containing moist air and COa. One calculation by Chameides (1979) was Iinked to the anticipated fixing of certain species as the sample atmosphere was very rapidly cooled by shock expansion. The other calculation by Hill and Rinker (1981) followed reaction chemistry as the sample atmosphere was relatively slowly cooled by convective mixing with the ambient air. The appropr~tene~ of the two calculations to the lightning process has already been discussed elsewhere (Hill, 1979; Picone et al., 1981). The intent of the present paper is to report on a complete analysis of the reaction chemistry of the moist air atmosphere begun by Hili and Rinker. The processes of exciting the atmosphere by lightning have also been expanded so that in Section 2 the chemistry involved in the hot lightning channel is discussed, and in Section 3 the chemistry involved in the ionized
sheath around the channel, excited by the well-known corona discharge, is discussed. In Section 4, the global consequences of the productions are investigated.
Z.CHANNELHEATINCfNMOISTAIR The present simulation is based on a model originally developed by Hill et al. (1980). Ambient air at 273.2 K is assumed to have the following composition: Nt ~589.86 mm Hg), O2 (158.23 mm Hgf, COz (0.25 mm Hg), Ha0 (4.58 mm Hg) and Ar (7.08 mm Hg). The lightning channel is assumed to cool to 3000 K by expansion, radiation and conduction. At that instant, perfect mixing of the channel air with the ambient surrounding air is assumed to commence at a constant rate. Thereafter, the temperature of the mixture is computed as a function of time, and the chemical reactions in the mixture are computed from the existing species concentrations and the temperature-dependent reaction rate constants. Initial concentrations of the starting species at 3000 K are calculated from a code given by Balzheiser er ol. f 1972), and thermodynamic data on the constituent species chosen are obtained from the JANAF (1970) tables. These initial concentrations are shown in Table 1.
Table 1. Species concentration in moist air at 3000 K Species N NZ NO NC% 0 02 As 19:9-A
Cont. molecm-’ 4.8 x lo-” 3.0 x 10-6 1.7 x lo-’
S&es & N,(; 0,
Cont. molecm-s
Species
3.8 x lo-* 7.15 x lo-“’ 8.4 x 1O-‘z
Hz0 HrOl OH % HNO 1391
Cont. mole cm- s 6.4 x 4.5 x 2.5 x 1.0x 5.8 x 1.05x
lo-’ lo-l4 10-s IO-*’ lo- I0 10-l’
Species HNO, HNO, NH NHa NH1 CHO
cont. mole cm - ’ 1.1 x 1.6 x 6.5 x 5.9 x 5.8 x 9.5 x
lo-l3 10-I’ 10-I’ lo-Is lo- t ’ 10-l’
The choice of constituent species in a simulation of this nature is always somewhat arbitrary. The criteria followed in the present simulation were that the constituents should be, as far as possible. the most abundant species produced. and that the kinetic data for the reactions involved should be available in the scientific literature. Fifty-seven reactions, for which the forward and reverse reaction rateconstants are known, were followed for the 24 reacting species given in Table 1. [The details of the reactions, for the sake of brevity, are not given here; but full information is available in B. A. Croweil’s thesis (1980)]. Xn the present simulation of the hot channel chemistry, 26 differential equations, one for the mole balance of each species, one for a total mote balance, and one for energy conservation, were integrated with respect to time using the newest form of the GEAR code (see A. Coucouvinos’ thesis, 1983). Normally, the integrations were carried out to 100 seconds after mixing commenced at the 3000 K initiai temperature for a variety of ambient-air mixing rates given by F. from 10 to 10,ooO s- ‘. [See Hill rr af. (1980) for a fuller discussion of the F0 parameter.] The results for the production of 11 species, following the hot channel chemistry in moist air, are shown in Figs I-1 1. Only the results for F, = 100 s- ’ are given in the figures. Curves for the ‘production’ of each species (on a molecular basis) and associated curves of temperature vs time are plotted on each figure. Production of a species was defined by the following equation Piff)=n~(t)-npFor-n:,
1
_I0 too
10.”
Tme
isecl
Fig. 2. Production of PJO, YS time. The rise in production of NO2 between about IO-” and 10“ s is partly associated with the fall in NO between the same times shown in Fig. 1. The increase in NO2 production after approximately I s is also associated with the falloffof NO production in Fig. 1
r
(1)
where Pi(t) at time t is the increase of species i per unit volume of the initial channel at t = 0 and a temperature of 3000 K, t+(r) is the number of moles of species i in a volume of the channel at time I that was originally unit volume at 3000 K and t = 0, ny is the number of moles
I
I
,
I
1
I
I
Fig. 3. Production of0, vs time. Ozone is too reactive at channel temperatures to persist in any significant quantities in the channel. The fall in O3 production to negative values after about 1 s is attributable to the negative F&t term in Equation (1)and the fact that 0, in the channel is continually used up, mainly in oxidizing NO.
Fig. 1. Production of NO and temperature change T vs time. Fixing of NO after lo-' s is apparent as T falls between fOm4and IO- 2 s. The fall in NO production after about I-IO s is partly correlated with the oxidation ofNO to NO:.
of species i in unit volume of ambient air at 273.2 K, F, is the volume of ambient air added per unit time to a unit volume of the channel air originally at 3000 K, and nI is a fictitious number of moles per unit volume representing the number of moles of species i which would be there in the absence of the lightning stroke. Since Pi is given in terms of the production i per unit volume of the channel at 3000K, then II; = t$ (273.2/3000). The most appropriate value of F, is still rather an open question. Hill, Rinker, and Wilson suggested originally that F, should probably be of the order of IO s- I. Subsequently, based on theory and observation of laboratory sparks, Picorte et ai. (1981) recommended a larger F. value of approximately 400 s- ‘.
Simulation of trace species production by li~tning
-2.0x10-'2 to 10-e
and
corona
1393
discharge in moist air
?OO Tome (set)
Time (SW
Fig. 4. Production of NaO vs time. NsO is clearly not fixed in this particular temperature vs time simulation; in fact, NrO is depleted from the ambient mixing air to a negative production value (as shown) by 0 atom interactions while temperatures remain above ambient. The constant negative NaO production value after 10W3s indicates the inertness of NzO in the ambient air inflow.
Fig. 6. Production of HNO, vs time. The large increase in HNOs production from approximately IO-’ to IO- 2 s is attributable to the increasing dominance of the NO f OH + M + HNOs + M forward reaction over the inverse reaction as the temperature diminishes and during the time that NO and OH concentrations are still relatively high. At around 1-10s. the HNO, appears to rise again slowly. This rise is attributable to theelimination of the HNOr destruction reaction due to the low (- 300 K) tem~rature and to the continued feed-in of OH, over a long time l-1M3s from the ambient air.
-10 -
o-
I
*
I
,
1
10-G
,
0
I
loo
Fig. 5. Production of CO vs time. Up to 1s,a negligible amount of CO is tixed. Between 10 and 1005, a small amount of CO is produced from the destruction of residual CHO by 0, according to the reaction CHO + O1 + CO + HaO,. Lightning is fed from many kilometers of channel and has a more protracted current pulse than the laboratory spark. Based also on the observed long persistence of the lightning channel, it seems likely to us that lightning has an F. value somewhat smafler than 400 s-l. In Figs I-f 1, curves are shown only for a favored value of F, = 100 s- ‘. Similarly in Table 2, the
Oil’
10-6 Tme
100
(set)
Fig. 7. Production of HN03 vs time. In our simulation, production of HNOJ arises from the reaction NO, + OH + M -+ HNOJ + M. At late times (mainly between I and 100 s), this reaction occurs with a relatively large prob. ability due to the late-time production of NO2 (see Fig. 2) and the continued feed-in of OH from ambient air. (Note that the rise of production is in reality much slower than actually appears from the production vs log time curve shown. A curve of production vs hnear time is easily shown to be tending to a saturation value of HNOJ production at infinite time).
Table 2. Production of trace speoies by a hot lightning channel in moist air* Species NO NO, co
Prod. mole stroke- * Species 2.5 X IO’ 1.9 6.85 x 1O-3
HNO HNO, HNO,
Prod. mole stroke-’ 2.0 x 10-s 1.7 x IO-’ 6.1 x lo-’
Species Hz02 HO2
Prod. mole stroke- ’ Species 2.4 x lo-’ 3.0 x IO-’
NH, NH,
Prod. mole stroke- ’ 9.0 x lo-’ 1.05 x lo-’
* Based on a mixing rate parameter f. = lOOs-’ and a volume of initial (3OOOK)channel air equal to 1.6 x IO*cm3 per stroke-‘, i.e. t a channel radius = IO cm and a height = 5 km.
I394
M. N.
~HETANABHOTLA~~
al.
3 000
:
Y
I: i; i
E
c
Fig. 8. Production of Hz vs time. Numerous reactions involved with Hz were included in our simulation. At times less than approx~teIy lo-‘s, the reaction H + OH - Hz + 0 appears mainly responsible for keeping up a reasonably sign&ant production of Hz; but when both H and OH concentrations arc reduced, the Hz production is reduced to zero.
10-c
100 Time
fsec)
Fig. 9. Production of OH vs time. The OH radical enters into 23 reactions in our simulation, and its interactions are complex. As shown in the figure, production of OH falls rapidly to zero as the temperature in the channel falls. A fuller discussion of the role of OH in channel chemistry was given by Hill and Rinkcr (1981).
final production values =lOOs-landatc=lOOs.
3. CORONA
are given
DBCHARGE IN
only
for F0
iwOrST AIR
This simulation was initiated in order to investigate whether N,O, which as seen in the previous section is not produced in the hot lightning channel, could be produced in the corona discharge accompanying a lightning stroke. In 1981, the production of N20 in thundercloud air, sampled by a special aircraft during lightning activity, was ably demonstrated by Levine et al. (1981 and 1983). In 1977, Donohoe ef al. (1977) had also demonstrated in the laboratory that electrical corona in air is a strong source of N,O, but that the hot
Fig. 10. Production of H20z vs time. The production of HsOs in the hot channel is compkx. Its production is related closely to OH and HO,. At IO-’ s, the main . . reactron provtdmg HtOl ISOH + Hz0 - H202 + 0, however, two other reactions, OH +OH + M - HzOz + M and H20z + 0 -) HO1 + OH have higher rates but are approximately balanced off against one another. At lo-‘s, OH+OH + M - H202 + M is the most dominant producer of H202. As shown by the fiattening of the curve after approximately 10-‘s, the reduce6 production of H202 is associated with the reduced concentration of OH (see Fig. 9). At very late times, between approximately 1 and 100 s, H20L is again produced to a small extent by the reaction HO, + HO1 - H202 + O1 which is driven by the intermixture of retained HO1 with HOz in ambient air. The rate of the reverse reaction is entirely negligible. (The apparent strong rise of H202 in this region is largely illusory and attributable to the timescale compression through the use of log time, as mentioned in the legend to Fig. 7.)
spark in air is not in itself a source of NzO. Thus, it became important to attempt to model the chemistry of trace species pr~uction in corona-excited air in order to identify the different processes occurring in the hot channel and cool corona regimes of lightning. Modelling of the chemistry in the corona region surrounding a lightning-stroke channel was first investigated by Hill et al. (1984). In that investigation, the m~eIling was carried out in dry air using 14 species and 84 reactions (see A. Coucouvinos’ thesis, 1983). This program was subsequently enlarged to describe corona in moist air, and it now includes 33 species and 174 reactions (see I. Rahmim’s thesis, 1984). As mentioned in Section 2, the choices of individual species and of the number of interactions to be retained are always somewhat arbitrary. It was clear that the chemical code of the corona simulation would be considerably larger than that of the hot channel simulation. This enlargement occurs because the criteria of the corona chemistry are considerably different from the hot channel criteria. For example, in the corona chemistry, it was recognized that the energy input occurs through
ionization
and excitation.
Thus
in the corona simulation, 15 of the 33 species are charged, and 3 species are excited atoms or molecules. One particularly important species of the corona
Simulation of trace species production by lightning and corona discharge in moist air
0-o 10-e
100 Tme
(WC)
Fig. 11. Productionof HO1 vs time. The production of HO, is quite complex; it is involved in 12 reactions in our simulation. At microsecond times, OH is probably the most important source of HOs through the reaction OH + OH * HOs + H, but there are a large number of competing reactions. At somewhat iater times (e.g. between 10-5-10-3 s), there is tittle doubt that OH is the dominant reactant in HO2 production. This is evident by the coK~~nding falls on the OH and HO, ewes in this region (see Fig. 9). The rise of HOr production after approximately 0.1 s is associated with the inflow of ambient Hot. However, the mechanism is indirect. (If ambient HO2 did not interact with the channel HOs, there would be no production since the P&t would subtract out the ambient inflow [see Equation (I)]. Differentiating Equation (I), one obtains dP,/dt = t;dc,/dr +c,do/dt, where u is the volume of the channel mixture at time t and ci is the concentration of species i. Thus a positive production rate of i can be obtained if c(du/dt is large and exceeds rdq/dt. This is happening in the production of HO1 in our simulation between 1 and 100 s, e.g. at 10 s, u = lo3 cm.‘, dc/dt =
-3.6x 10-‘7moiecm-3s-‘, c = 5.9 x 10-‘Jmolecrn-3 and deldt = 1oOcm3s-‘. Thus dP/dt 2: i5.4 x lOa mole s- t, which is consistent with the value in Fig. 11.)(Note that the rise in the curve is exaggerated by the logarithmic time scale.)
excitation is NI(A3Z) which is primarily the source of NtO (see Hill et al., 1984). Of the 174 reactions followed in the moist air corona calculation, 124 involve charged species (see I. Rahmim, 1984). Another complication was introduced into the moist air corona simulation by the possible involvement of hydrated ions. This aspect of the chemistry of lightning was suggested by Ferguson and Libby (1971) as a possible source of nitrogen fixation through the intermediary of the reaction H,NOb (or NO’ 3HrO) + HZ0 -* HNO1 + H,O: (H,O+ 2HrO). In order to
investigate whether this reaction is a potential source of HNOI, we felt compelled to include a large number of hydrated ions and their interactions in our simulation. Full details of the corona model and of the dry air simulation were given earlier (Hill er al., 1984; Coucouvinos, 1983). The moist air simulation is very similar and details are not given here. Partial results for the moist air corona simuIation are given in Tabte 3. Productions P in column 3 of the table are for thin horizontal sections, I cm high, of the corona air as a function of height H in the cylinder of corona air ( - 1 m radius) surrounding the lightning channel. These productions, in molecules per cm, are for the whole corona pulse lasting 60 w. The total productions in moles per pulse in column 2 are the productions integrated over all heights from the ground upward. All production vs height curves show basically the same type of exponential decrease with height calculated by the equations given in column 3. However, apart from the basic production differences at zero height, the differences between the height-decay constants appear to be real; as indicated by the values of the least-squares correlation coefikients given in brackets. Values of the height-decay constants are presumably determined by the particular chemical reactions, but the exponential type of height decrease is undoubtedly attributable to the details of the Lin-Uman-Standler (1980) model of corona current which has a specific exponential dependence. The value of the L-U-S height-decay constant used in our simulation was -0.667 km- * (see A. Coucouvinos’ thesis,
1983).
Several aspects of the corona production results might be emphasized. Firstly, the production of N20 per pulse computed for dry air (Coucouvinos’ thesis) is only slightly larger (1.8 x 10e3 mole pulse-‘) than the NzO yield now computed in moist air. This is, as might be expected, consistent with a small conversion of nitrogen to other species such as HNOr, etc. Secondly, unlike in the hot channel production, the relative yield of OJ in corona is large, in fact the largest ofall the new species generated. Possible gtobal significance of this generation is discussed later. Thirdly, the production of NO by corona is very significantly less (by approximately 4 orders of magnitude) than the production per stroke in the hot channel (i.e. 25 mole stroke- r, see Tabte 2). If the different input energies in a corona pulse (IO5 J, see Hill er al., 1984) and in a
Table 3. Production of trace species bv a corona discharge in moist air Species
N,O NO 03
HNOt
H NO2
Total production (mole pulse- *) 1.6 x 3.5 x 8.3 x 7.2 x 4.2 x 2.0 x
1O-3 IO-3 10-s lo-” 1O-5 10-7
1395
Production vs height P~molesulelcm-heiehtl vs H(kmj Eouation In(P) = - 1.05H+ 36.7 (corr. coeff. o - 1.0) in(P) = -0.9528 + 37.4 (corr. coeff. = - 0.9987) h(P) = - 0.9668 + 38.2 (corr. coeff. = - 0.9982) In(P) = - 09985H + 35.8 (corr. coeff. = - 0.9985) in(P) = - 1.7037H + 33.3 (corr. coeff. = - 0.9997) In(P) = -2.6168H+28.4 :corr. co& = -0.9951)
I396
MM. N. BHETANABHOTLA
Iightning stroke (5 x IO’.& see Hill er al., 1980) are taken into account, then the NO yield per Joule in the channel exceeds that in the corona by a factor of only 14. Further, if one considers the total production of all new species arising in lightning, there is an even better one-to-one comparison between yields and energies dissipated in the channel and the corona. Thus, by totaling up the productions in rabies 2 and 3, we obtain 3.6 x lo-’ new species per Joute in the case of channel heating and 1.4 x lo-’ new species per Joule in the case of corona, i.e. agreement on an energy basis to within a factor of between 2 and 3. Fourthly, we conclude that the Ferguson-Libby process cannot account for a significant contribution to nitrogen fixation via HNOz production, i.e. relative to either the fixation via NO and NOz in the case of corona and certainly relative to the fixation via NO in the hot channel of lightning. It should be emphasized that in order to check this point, the HNOs production by corona was derived in our simulation entirely from the reactions involved in the Ferguson-Libby process. Further analysis may be necessary in order to decide whether other processes may also contribute to the HN02 production in corona, for example, whether the OH-type interactions of the type dominant in the channel at high tem~ratures might still contribute to HNOz production at the low ambient temperature of the corona. However, it is still not anticipated that this HNOZ production will be comparable with the NO production. The productions of HO2 and H202, although not included because they are very small in Table 3, are only of the order of 1 to 2 x IO-‘moles per pulse. Productions of HOa and Hz@, however, were approximately o&y an order of magnitude higher in the hot channel (- 3 x 10W3molesstroke-‘). In the case of the corona simulation, again because of the emphasis placed on the test of the hydrated-ion chemistry, the analysis of the OH-type of HO1 and HtOt productions was not fully implemented. This type of OH-associated chemistry would considerabIy expand the corona simulation beyond its present size. Further study might be warranted if HZ02 and HO2 are more widely generated by coronas around power lines and thundersto~ clouds, generally, than in the air merely surrounding lightning stroke channels.
Table 4.
er al
4. GLOBAL PROD~CFIONS
The global productions of the major trace species produced by complete I~ghtnin~ strokes (i.e. both the return current stroke and its accompanying corona sheath) in realistic air (i.e. containing moisture) are given in Table 4. These estimates sere made by combining productions from Tables 2 and 3. but corona production is generally a very minor contribution. Clearly, the major species produced by lightning is NO, however, this product is oxidized slowly (over minutes) to NOz. It may be noticed that the NO, (i.e. NO + NO& production in Table 4 is approxi~tely a factor of 6 less than the NO, production previously estimated (Hill et al., 1980). The present Lowerestimate is a direct consequence of the three assumption changes, namely that the channel radius at 3000 K is 10 cm (instead of 16 cm as previously), that the global stroke rate is 100 s-t (instead of 300 s-t as previously), and that the F, value is JOOs-’ (instead of 10 s- * as previously). These changes reflect trends in the estimates of lightning phenomenology since 1980. It is also to be noticed in Tabie 4 that the total OJ produced in the corona envelope surrounding the channel is a small fraction of that required to oxidiie all of the NO converted into NOa. This conversion is therefore mainly carried out by ambient O3 and must therefore await complete mixing. Most of the coronaproduced 0s is consumed in oxidation of NO, and it is therefore evident that the corona accompanying lightning strokes does not materially add O3 to the global environment. It should also be noticed that the production of O3 computed in the present simulation does not include any O3 that may be produced in widespread corona that occurs between droplets in clouds, in the high field regions which are induced below and near thunderstorm clouds, or in the regions surrounding high voltage Rower transmission lines. The amounts of HNOI and HN03 added to the global atmosphere per year are less than one percent of the NO, contributed directly by lightning per year. This result is consistent with the observation that NOT and NO; ions are not abundant following lightning {see Hill and Rinker, 1981). The cases of H202 and HOz are interesting. Kok
Global productions of certain trace species by lightning’
Species
Production moles-(tonnes) y - ’
NO NGz
7.9 x lO”‘(2.4 x i06) HNOZ 6.0 x 10’ (2.8 x IO”) HNO,
Nz0 co 0,
Species
5.0 x IO6 (2.2 x lo?) HLO, 2.2 x IO- (6.2 x lo*) HO, 2.5 x lo- (I.2 x IO-‘)
Production moles-( tonnes) y - ’ 5.3 x 10*(2..5x 10’)
1.9 x lO’(1.2x IO’) 9.5 x t06(3.2 x IO’) 9.5 x iP(3.2 X 102)
* Based on 100 strokes s-l. Includes both hot channel and corona
producrions.
Simulation
of trace species production
by lightning
(1980, 198 1) and others (Zika et al., 1982) have shown that H20, appears in rainwater and that lightning activity is probably the source of this enrichment. Calculated equilibrium densities of HLO, and HO1 in ambient air at 273 K and 1 atm. pressure are approximately 1.66 x lo- ” and 1.66 x lO-‘5 molecm-‘, respectively (Crowell, 1980). [These values are roughly in accord with the HzO, troposphericconcentration of 4.4 x 10-*4mol cm-’ estimated by Penkett er al. (1979)]. From these values, rough approximation of the global amounts of Hz02 and HOz in the atmosphere are of the order of 1OL2 and 10” moles, respectively. The estimates of 10’ moles y-r of H202 and HO? produced by lightning given in Table 4 indicate that, on a global scale, lightning cannot be considered an important source of these species. Ac~nowledgemenls-These investigations were supported in part by the National Science Foundation under grants ATM17568 and ATM-8100164. Part of the work by one of us (R.D.H.) was also supported by the Office of Naval Research under contract NOC014-80-C-0293.
Energy,
M.
R. and
discharge
in motst au
1397
Gritfing G. W. (1977) Ozone and oxides of nitrogen production during thunderstorms. J. yrophJs. Res. 82. 943-950. Hill R. D.. Rinker NO, production 1077-1078.
R. G. and Wilson D. f 1978) Mechanism of by lightning. Trans. .dm. Geoph_vs. L’n. 59.
Hill R. D. (1979) On the production of nitric oxide by lightning. Geophys. Rrs. Left. 6, 945-947. Hill R. D., Rinker R. G. and Wilson H. D. (1980) Atmospheric nitrogen fixation by lightning. J. atmos. Sci. 37, 179-192. Hili R. D. and Rinker R. G (1981) Production of nitrateions and other trace species by lightnmg. J. grophxs. Res. 86, 3203-3209. Hill R. D., Rinker R. G. and Coucouvinos A. (1981) Nitrous oxide production by lightning. J. geophys. Res. 89, 141 l-1421. JANAF (1970) ThermodJnamicTables (2nd Edn). Publication NSRDSNBS37. U.S. National Bureau of Standards, Washington. D.C. Kok G. L. (1980) Measurements of hydrogen peroxide in rainwater. Atmospheric Encironment 14, 653-656. Kok G. L. ( I98 I) Measurements of hydrogen peroxide in the OSCAR Program. Report to Coordinating Research Council, Atlanta GA, NTIS-PB-82-256017. Levine J. S., Brooke R. R.. Shaw E. F. and Chameides W. L. (1981) Aircraft measurements of N20 enhancement in thunderstorm lightning. Trans. Am. Geophys. L’n. 62, 290. Levine J. S. and Shaw E. F. (1983) in situ aircraft measurements of enhanced levels of N,O associated with thunderstorm lightning. Nature, Land. 303, 312-314.
REFERENCES Balzhiser R E., Samuels Chemical Engineering
and corona
Eliassen
Thermodynamics: and Equilibrium.
J. D. (1972)
The
Study
of
Enrrop~, Prentice-Ha& Englewood Cliffs, NJ, pp. 506-527. Chameides W L., Stedmanb. H., Dickerson R. R., Rusch D. W. and Cicerone R. J. (197’7) NO, production in lightning. J. atmos. Sci. 34, 143-149. Chameides W. L. (1979) The implications of CO production in electrical discharges. Geophys. Res. Left. 6, 287-290. Coucouvinos A. (1983) Kinetic studies in ammonia synthesis. Nitrous oxide production by lightning. M.S. thesis, University of California, Santa Barbara, CA. Crowell B. A. (1980) Production of chemical species by lightning. M.S. thesis, University of California. Santa Barbara, CA. Donohoe K. G., Shair F. H. and WulfO. R. (1977) Production of 0s. NO and N,O in a pulsed discharge at I arm. Ind. Engng Chem. Fundnm. 16, 208-215. Ferguson E. E and Libby W. F. (1971) Mechanism for the fixation of nitrogen by lightning. Nature, Land. 229, 37.
Lin Y. T.. Uman M. A. and Standler R. B. (19801 Lightning return stroke models. J. geophys. Res. 85, 1571-1583. Penkett S. A.. Jones B. M. R.. Brice K. A. and Egglcton A. E. G. (1979) The importance of atmospheric ozone and hydrogen peroxide in oxidizing sulfur dioxide in cloud and rainwater. Atmospheric Erwironment 13, 123-I 37. Picone J. M.. Boris J. P., Greig J. R., Raleigh M. and Fernsler R. F. (1981) Convective cooling of lightning channels. J. atmos. Sci. 38, 20X-2062. Rahmin I. (1984) Production of trace species in atmospheric coronas. MS. thesis. University of California. Santa Barbara, CA. Tuck A. F. (1976) Production of nitrogen oxides by lightning. Q. Jl R. met. Sot. 102, 749-755. Zipf E. C. and Dubin M. (1976) Laboratory studies on the formation of NO, compounds and ozone by lightning.
Trans. Am. Geophys. Un. 51, 965. Zika R., Saltzman W. L., Chameides W. L. and Davis D. D. (1982) HtOr levels in rainwater collected in South Florida and the Bahama Islands. J. geophys. Res. 87, 3017-5017.
received 5 November
1984; in revisedform
21 December 1984 and receivedfor 1985)
publication 4 February
Abstract-Numerical simulations of chemical processes initiated in moist air by lightning strokes and lightning coronas indite that the amounts of major new species generated are not very different from the amounts previously found in dry air. Thus, the major new species produced globally in moist air are estimated to be: 2.4 megatonnes NO y-t, 0.28 megatonnes NOa y-l and 220 tonnes NaO y- ‘. The minor species, ozone and those containing hydrogen released by lightning from water in moist air are: 1.2 kilotonnes C&Y;*~?,S kilotonnes HNOz y-t, 1.2 kilotonnes HNOJ y-t, 0.32 kilotonnes Hr02 y-’ and 0.32 kilotonnes 2 Key word index: ~i~tning
chemistry, corona chemistry, nitrogen fixation, wet air chemistry,
I.INTRODUCTION
Calculations of the production of trace species in the atmosphere by electrical and chemical processes initiated by fightning have been reported by Zipf and Dubin (1976), Tuck (1976), Chameides et al. (1977), Griffing (1977), Hill etal.(1978) and others. The abovenamed calculations were initiated in dry air. Two subsequent calculations employed more realistic atmospheres containing moist air and COa. One calculation by Chameides (1979) was Iinked to the anticipated fixing of certain species as the sample atmosphere was very rapidly cooled by shock expansion. The other calculation by Hill and Rinker (1981) followed reaction chemistry as the sample atmosphere was relatively slowly cooled by convective mixing with the ambient air. The appropr~tene~ of the two calculations to the lightning process has already been discussed elsewhere (Hill, 1979; Picone et al., 1981). The intent of the present paper is to report on a complete analysis of the reaction chemistry of the moist air atmosphere begun by Hili and Rinker. The processes of exciting the atmosphere by lightning have also been expanded so that in Section 2 the chemistry involved in the hot lightning channel is discussed, and in Section 3 the chemistry involved in the ionized
sheath around the channel, excited by the well-known corona discharge, is discussed. In Section 4, the global consequences of the productions are investigated.
Z.CHANNELHEATINCfNMOISTAIR The present simulation is based on a model originally developed by Hill et al. (1980). Ambient air at 273.2 K is assumed to have the following composition: Nt ~589.86 mm Hg), O2 (158.23 mm Hgf, COz (0.25 mm Hg), Ha0 (4.58 mm Hg) and Ar (7.08 mm Hg). The lightning channel is assumed to cool to 3000 K by expansion, radiation and conduction. At that instant, perfect mixing of the channel air with the ambient surrounding air is assumed to commence at a constant rate. Thereafter, the temperature of the mixture is computed as a function of time, and the chemical reactions in the mixture are computed from the existing species concentrations and the temperature-dependent reaction rate constants. Initial concentrations of the starting species at 3000 K are calculated from a code given by Balzheiser er ol. f 1972), and thermodynamic data on the constituent species chosen are obtained from the JANAF (1970) tables. These initial concentrations are shown in Table 1.
Table 1. Species concentration in moist air at 3000 K Species N NZ NO NC% 0 02 As 19:9-A
Cont. molecm-’ 4.8 x lo-” 3.0 x 10-6 1.7 x lo-’
S&es & N,(; 0,
Cont. molecm-s
Species
3.8 x lo-* 7.15 x lo-“’ 8.4 x 1O-‘z
Hz0 HrOl OH % HNO 1391
Cont. mole cm- s 6.4 x 4.5 x 2.5 x 1.0x 5.8 x 1.05x
lo-’ lo-l4 10-s IO-*’ lo- I0 10-l’
Species HNO, HNO, NH NHa NH1 CHO
cont. mole cm - ’ 1.1 x 1.6 x 6.5 x 5.9 x 5.8 x 9.5 x
lo-l3 10-I’ 10-I’ lo-Is lo- t ’ 10-l’
The choice of constituent species in a simulation of this nature is always somewhat arbitrary. The criteria followed in the present simulation were that the constituents should be, as far as possible. the most abundant species produced. and that the kinetic data for the reactions involved should be available in the scientific literature. Fifty-seven reactions, for which the forward and reverse reaction rateconstants are known, were followed for the 24 reacting species given in Table 1. [The details of the reactions, for the sake of brevity, are not given here; but full information is available in B. A. Croweil’s thesis (1980)]. Xn the present simulation of the hot channel chemistry, 26 differential equations, one for the mole balance of each species, one for a total mote balance, and one for energy conservation, were integrated with respect to time using the newest form of the GEAR code (see A. Coucouvinos’ thesis, 1983). Normally, the integrations were carried out to 100 seconds after mixing commenced at the 3000 K initiai temperature for a variety of ambient-air mixing rates given by F. from 10 to 10,ooO s- ‘. [See Hill rr af. (1980) for a fuller discussion of the F0 parameter.] The results for the production of 11 species, following the hot channel chemistry in moist air, are shown in Figs I-1 1. Only the results for F, = 100 s- ’ are given in the figures. Curves for the ‘production’ of each species (on a molecular basis) and associated curves of temperature vs time are plotted on each figure. Production of a species was defined by the following equation Piff)=n~(t)-npFor-n:,
1
_I0 too
10.”
Tme
isecl
Fig. 2. Production of PJO, YS time. The rise in production of NO2 between about IO-” and 10“ s is partly associated with the fall in NO between the same times shown in Fig. 1. The increase in NO2 production after approximately I s is also associated with the falloffof NO production in Fig. 1
r
(1)
where Pi(t) at time t is the increase of species i per unit volume of the initial channel at t = 0 and a temperature of 3000 K, t+(r) is the number of moles of species i in a volume of the channel at time I that was originally unit volume at 3000 K and t = 0, ny is the number of moles
I
I
,
I
1
I
I
Fig. 3. Production of0, vs time. Ozone is too reactive at channel temperatures to persist in any significant quantities in the channel. The fall in O3 production to negative values after about 1 s is attributable to the negative F&t term in Equation (1)and the fact that 0, in the channel is continually used up, mainly in oxidizing NO.
Fig. 1. Production of NO and temperature change T vs time. Fixing of NO after lo-' s is apparent as T falls between fOm4and IO- 2 s. The fall in NO production after about I-IO s is partly correlated with the oxidation ofNO to NO:.
of species i in unit volume of ambient air at 273.2 K, F, is the volume of ambient air added per unit time to a unit volume of the channel air originally at 3000 K, and nI is a fictitious number of moles per unit volume representing the number of moles of species i which would be there in the absence of the lightning stroke. Since Pi is given in terms of the production i per unit volume of the channel at 3000K, then II; = t$ (273.2/3000). The most appropriate value of F, is still rather an open question. Hill, Rinker, and Wilson suggested originally that F, should probably be of the order of IO s- I. Subsequently, based on theory and observation of laboratory sparks, Picorte et ai. (1981) recommended a larger F. value of approximately 400 s- ‘.
Simulation of trace species production by li~tning
-2.0x10-'2 to 10-e
and
corona
1393
discharge in moist air
?OO Tome (set)
Time (SW
Fig. 4. Production of NaO vs time. NsO is clearly not fixed in this particular temperature vs time simulation; in fact, NrO is depleted from the ambient mixing air to a negative production value (as shown) by 0 atom interactions while temperatures remain above ambient. The constant negative NaO production value after 10W3s indicates the inertness of NzO in the ambient air inflow.
Fig. 6. Production of HNO, vs time. The large increase in HNOs production from approximately IO-’ to IO- 2 s is attributable to the increasing dominance of the NO f OH + M + HNOs + M forward reaction over the inverse reaction as the temperature diminishes and during the time that NO and OH concentrations are still relatively high. At around 1-10s. the HNO, appears to rise again slowly. This rise is attributable to theelimination of the HNOr destruction reaction due to the low (- 300 K) tem~rature and to the continued feed-in of OH, over a long time l-1M3s from the ambient air.
-10 -
o-
I
*
I
,
1
10-G
,
0
I
loo
Fig. 5. Production of CO vs time. Up to 1s,a negligible amount of CO is tixed. Between 10 and 1005, a small amount of CO is produced from the destruction of residual CHO by 0, according to the reaction CHO + O1 + CO + HaO,. Lightning is fed from many kilometers of channel and has a more protracted current pulse than the laboratory spark. Based also on the observed long persistence of the lightning channel, it seems likely to us that lightning has an F. value somewhat smafler than 400 s-l. In Figs I-f 1, curves are shown only for a favored value of F, = 100 s- ‘. Similarly in Table 2, the
Oil’
10-6 Tme
100
(set)
Fig. 7. Production of HN03 vs time. In our simulation, production of HNOJ arises from the reaction NO, + OH + M -+ HNOJ + M. At late times (mainly between I and 100 s), this reaction occurs with a relatively large prob. ability due to the late-time production of NO2 (see Fig. 2) and the continued feed-in of OH from ambient air. (Note that the rise of production is in reality much slower than actually appears from the production vs log time curve shown. A curve of production vs hnear time is easily shown to be tending to a saturation value of HNOJ production at infinite time).
Table 2. Production of trace speoies by a hot lightning channel in moist air* Species NO NO, co
Prod. mole stroke- * Species 2.5 X IO’ 1.9 6.85 x 1O-3
HNO HNO, HNO,
Prod. mole stroke-’ 2.0 x 10-s 1.7 x IO-’ 6.1 x lo-’
Species Hz02 HO2
Prod. mole stroke- ’ Species 2.4 x lo-’ 3.0 x IO-’
NH, NH,
Prod. mole stroke- ’ 9.0 x lo-’ 1.05 x lo-’
* Based on a mixing rate parameter f. = lOOs-’ and a volume of initial (3OOOK)channel air equal to 1.6 x IO*cm3 per stroke-‘, i.e. t a channel radius = IO cm and a height = 5 km.
I394
M. N.
~HETANABHOTLA~~
al.
3 000
:
Y
I: i; i
E
c
Fig. 8. Production of Hz vs time. Numerous reactions involved with Hz were included in our simulation. At times less than approx~teIy lo-‘s, the reaction H + OH - Hz + 0 appears mainly responsible for keeping up a reasonably sign&ant production of Hz; but when both H and OH concentrations arc reduced, the Hz production is reduced to zero.
10-c
100 Time
fsec)
Fig. 9. Production of OH vs time. The OH radical enters into 23 reactions in our simulation, and its interactions are complex. As shown in the figure, production of OH falls rapidly to zero as the temperature in the channel falls. A fuller discussion of the role of OH in channel chemistry was given by Hill and Rinkcr (1981).
final production values =lOOs-landatc=lOOs.
3. CORONA
are given
DBCHARGE IN
only
for F0
iwOrST AIR
This simulation was initiated in order to investigate whether N,O, which as seen in the previous section is not produced in the hot lightning channel, could be produced in the corona discharge accompanying a lightning stroke. In 1981, the production of N20 in thundercloud air, sampled by a special aircraft during lightning activity, was ably demonstrated by Levine et al. (1981 and 1983). In 1977, Donohoe ef al. (1977) had also demonstrated in the laboratory that electrical corona in air is a strong source of N,O, but that the hot
Fig. 10. Production of H20z vs time. The production of HsOs in the hot channel is compkx. Its production is related closely to OH and HO,. At IO-’ s, the main . . reactron provtdmg HtOl ISOH + Hz0 - H202 + 0, however, two other reactions, OH +OH + M - HzOz + M and H20z + 0 -) HO1 + OH have higher rates but are approximately balanced off against one another. At lo-‘s, OH+OH + M - H202 + M is the most dominant producer of H202. As shown by the fiattening of the curve after approximately 10-‘s, the reduce6 production of H202 is associated with the reduced concentration of OH (see Fig. 9). At very late times, between approximately 1 and 100 s, H20L is again produced to a small extent by the reaction HO, + HO1 - H202 + O1 which is driven by the intermixture of retained HO1 with HOz in ambient air. The rate of the reverse reaction is entirely negligible. (The apparent strong rise of H202 in this region is largely illusory and attributable to the timescale compression through the use of log time, as mentioned in the legend to Fig. 7.)
spark in air is not in itself a source of NzO. Thus, it became important to attempt to model the chemistry of trace species pr~uction in corona-excited air in order to identify the different processes occurring in the hot channel and cool corona regimes of lightning. Modelling of the chemistry in the corona region surrounding a lightning-stroke channel was first investigated by Hill et al. (1984). In that investigation, the m~eIling was carried out in dry air using 14 species and 84 reactions (see A. Coucouvinos’ thesis, 1983). This program was subsequently enlarged to describe corona in moist air, and it now includes 33 species and 174 reactions (see I. Rahmim’s thesis, 1984). As mentioned in Section 2, the choices of individual species and of the number of interactions to be retained are always somewhat arbitrary. It was clear that the chemical code of the corona simulation would be considerably larger than that of the hot channel simulation. This enlargement occurs because the criteria of the corona chemistry are considerably different from the hot channel criteria. For example, in the corona chemistry, it was recognized that the energy input occurs through
ionization
and excitation.
Thus
in the corona simulation, 15 of the 33 species are charged, and 3 species are excited atoms or molecules. One particularly important species of the corona
Simulation of trace species production by lightning and corona discharge in moist air
0-o 10-e
100 Tme
(WC)
Fig. 11. Productionof HO1 vs time. The production of HO, is quite complex; it is involved in 12 reactions in our simulation. At microsecond times, OH is probably the most important source of HOs through the reaction OH + OH * HOs + H, but there are a large number of competing reactions. At somewhat iater times (e.g. between 10-5-10-3 s), there is tittle doubt that OH is the dominant reactant in HO2 production. This is evident by the coK~~nding falls on the OH and HO, ewes in this region (see Fig. 9). The rise of HOr production after approximately 0.1 s is associated with the inflow of ambient Hot. However, the mechanism is indirect. (If ambient HO2 did not interact with the channel HOs, there would be no production since the P&t would subtract out the ambient inflow [see Equation (I)]. Differentiating Equation (I), one obtains dP,/dt = t;dc,/dr +c,do/dt, where u is the volume of the channel mixture at time t and ci is the concentration of species i. Thus a positive production rate of i can be obtained if c(du/dt is large and exceeds rdq/dt. This is happening in the production of HO1 in our simulation between 1 and 100 s, e.g. at 10 s, u = lo3 cm.‘, dc/dt =
-3.6x 10-‘7moiecm-3s-‘, c = 5.9 x 10-‘Jmolecrn-3 and deldt = 1oOcm3s-‘. Thus dP/dt 2: i5.4 x lOa mole s- t, which is consistent with the value in Fig. 11.)(Note that the rise in the curve is exaggerated by the logarithmic time scale.)
excitation is NI(A3Z) which is primarily the source of NtO (see Hill et al., 1984). Of the 174 reactions followed in the moist air corona calculation, 124 involve charged species (see I. Rahmim, 1984). Another complication was introduced into the moist air corona simulation by the possible involvement of hydrated ions. This aspect of the chemistry of lightning was suggested by Ferguson and Libby (1971) as a possible source of nitrogen fixation through the intermediary of the reaction H,NOb (or NO’ 3HrO) + HZ0 -* HNO1 + H,O: (H,O+ 2HrO). In order to
investigate whether this reaction is a potential source of HNOI, we felt compelled to include a large number of hydrated ions and their interactions in our simulation. Full details of the corona model and of the dry air simulation were given earlier (Hill er al., 1984; Coucouvinos, 1983). The moist air simulation is very similar and details are not given here. Partial results for the moist air corona simuIation are given in Tabte 3. Productions P in column 3 of the table are for thin horizontal sections, I cm high, of the corona air as a function of height H in the cylinder of corona air ( - 1 m radius) surrounding the lightning channel. These productions, in molecules per cm, are for the whole corona pulse lasting 60 w. The total productions in moles per pulse in column 2 are the productions integrated over all heights from the ground upward. All production vs height curves show basically the same type of exponential decrease with height calculated by the equations given in column 3. However, apart from the basic production differences at zero height, the differences between the height-decay constants appear to be real; as indicated by the values of the least-squares correlation coefikients given in brackets. Values of the height-decay constants are presumably determined by the particular chemical reactions, but the exponential type of height decrease is undoubtedly attributable to the details of the Lin-Uman-Standler (1980) model of corona current which has a specific exponential dependence. The value of the L-U-S height-decay constant used in our simulation was -0.667 km- * (see A. Coucouvinos’ thesis,
1983).
Several aspects of the corona production results might be emphasized. Firstly, the production of N20 per pulse computed for dry air (Coucouvinos’ thesis) is only slightly larger (1.8 x 10e3 mole pulse-‘) than the NzO yield now computed in moist air. This is, as might be expected, consistent with a small conversion of nitrogen to other species such as HNOr, etc. Secondly, unlike in the hot channel production, the relative yield of OJ in corona is large, in fact the largest ofall the new species generated. Possible gtobal significance of this generation is discussed later. Thirdly, the production of NO by corona is very significantly less (by approximately 4 orders of magnitude) than the production per stroke in the hot channel (i.e. 25 mole stroke- r, see Tabte 2). If the different input energies in a corona pulse (IO5 J, see Hill er al., 1984) and in a
Table 3. Production of trace species bv a corona discharge in moist air Species
N,O NO 03
HNOt
H NO2
Total production (mole pulse- *) 1.6 x 3.5 x 8.3 x 7.2 x 4.2 x 2.0 x
1O-3 IO-3 10-s lo-” 1O-5 10-7
1395
Production vs height P~molesulelcm-heiehtl vs H(kmj Eouation In(P) = - 1.05H+ 36.7 (corr. coeff. o - 1.0) in(P) = -0.9528 + 37.4 (corr. coeff. = - 0.9987) h(P) = - 0.9668 + 38.2 (corr. coeff. = - 0.9982) In(P) = - 09985H + 35.8 (corr. coeff. = - 0.9985) in(P) = - 1.7037H + 33.3 (corr. coeff. = - 0.9997) In(P) = -2.6168H+28.4 :corr. co& = -0.9951)
I396
MM. N. BHETANABHOTLA
Iightning stroke (5 x IO’.& see Hill er al., 1980) are taken into account, then the NO yield per Joule in the channel exceeds that in the corona by a factor of only 14. Further, if one considers the total production of all new species arising in lightning, there is an even better one-to-one comparison between yields and energies dissipated in the channel and the corona. Thus, by totaling up the productions in rabies 2 and 3, we obtain 3.6 x lo-’ new species per Joute in the case of channel heating and 1.4 x lo-’ new species per Joule in the case of corona, i.e. agreement on an energy basis to within a factor of between 2 and 3. Fourthly, we conclude that the Ferguson-Libby process cannot account for a significant contribution to nitrogen fixation via HNOz production, i.e. relative to either the fixation via NO and NOz in the case of corona and certainly relative to the fixation via NO in the hot channel of lightning. It should be emphasized that in order to check this point, the HNOs production by corona was derived in our simulation entirely from the reactions involved in the Ferguson-Libby process. Further analysis may be necessary in order to decide whether other processes may also contribute to the HN02 production in corona, for example, whether the OH-type interactions of the type dominant in the channel at high tem~ratures might still contribute to HNOz production at the low ambient temperature of the corona. However, it is still not anticipated that this HNOZ production will be comparable with the NO production. The productions of HO2 and H202, although not included because they are very small in Table 3, are only of the order of 1 to 2 x IO-‘moles per pulse. Productions of HOa and Hz@, however, were approximately o&y an order of magnitude higher in the hot channel (- 3 x 10W3molesstroke-‘). In the case of the corona simulation, again because of the emphasis placed on the test of the hydrated-ion chemistry, the analysis of the OH-type of HO1 and HtOt productions was not fully implemented. This type of OH-associated chemistry would considerabIy expand the corona simulation beyond its present size. Further study might be warranted if HZ02 and HO2 are more widely generated by coronas around power lines and thundersto~ clouds, generally, than in the air merely surrounding lightning stroke channels.
Table 4.
er al
4. GLOBAL PROD~CFIONS
The global productions of the major trace species produced by complete I~ghtnin~ strokes (i.e. both the return current stroke and its accompanying corona sheath) in realistic air (i.e. containing moisture) are given in Table 4. These estimates sere made by combining productions from Tables 2 and 3. but corona production is generally a very minor contribution. Clearly, the major species produced by lightning is NO, however, this product is oxidized slowly (over minutes) to NOz. It may be noticed that the NO, (i.e. NO + NO& production in Table 4 is approxi~tely a factor of 6 less than the NO, production previously estimated (Hill et al., 1980). The present Lowerestimate is a direct consequence of the three assumption changes, namely that the channel radius at 3000 K is 10 cm (instead of 16 cm as previously), that the global stroke rate is 100 s-t (instead of 300 s-t as previously), and that the F, value is JOOs-’ (instead of 10 s- * as previously). These changes reflect trends in the estimates of lightning phenomenology since 1980. It is also to be noticed in Tabie 4 that the total OJ produced in the corona envelope surrounding the channel is a small fraction of that required to oxidiie all of the NO converted into NOa. This conversion is therefore mainly carried out by ambient O3 and must therefore await complete mixing. Most of the coronaproduced 0s is consumed in oxidation of NO, and it is therefore evident that the corona accompanying lightning strokes does not materially add O3 to the global environment. It should also be noticed that the production of O3 computed in the present simulation does not include any O3 that may be produced in widespread corona that occurs between droplets in clouds, in the high field regions which are induced below and near thunderstorm clouds, or in the regions surrounding high voltage Rower transmission lines. The amounts of HNOI and HN03 added to the global atmosphere per year are less than one percent of the NO, contributed directly by lightning per year. This result is consistent with the observation that NOT and NO; ions are not abundant following lightning {see Hill and Rinker, 1981). The cases of H202 and HOz are interesting. Kok
Global productions of certain trace species by lightning’
Species
Production moles-(tonnes) y - ’
NO NGz
7.9 x lO”‘(2.4 x i06) HNOZ 6.0 x 10’ (2.8 x IO”) HNO,
Nz0 co 0,
Species
5.0 x IO6 (2.2 x lo?) HLO, 2.2 x IO- (6.2 x lo*) HO, 2.5 x lo- (I.2 x IO-‘)
Production moles-( tonnes) y - ’ 5.3 x 10*(2..5x 10’)
1.9 x lO’(1.2x IO’) 9.5 x t06(3.2 x IO’) 9.5 x iP(3.2 X 102)
* Based on 100 strokes s-l. Includes both hot channel and corona
producrions.
Simulation
of trace species production
by lightning
(1980, 198 1) and others (Zika et al., 1982) have shown that H20, appears in rainwater and that lightning activity is probably the source of this enrichment. Calculated equilibrium densities of HLO, and HO1 in ambient air at 273 K and 1 atm. pressure are approximately 1.66 x lo- ” and 1.66 x lO-‘5 molecm-‘, respectively (Crowell, 1980). [These values are roughly in accord with the HzO, troposphericconcentration of 4.4 x 10-*4mol cm-’ estimated by Penkett er al. (1979)]. From these values, rough approximation of the global amounts of Hz02 and HOz in the atmosphere are of the order of 1OL2 and 10” moles, respectively. The estimates of 10’ moles y-r of H202 and HO? produced by lightning given in Table 4 indicate that, on a global scale, lightning cannot be considered an important source of these species. Ac~nowledgemenls-These investigations were supported in part by the National Science Foundation under grants ATM17568 and ATM-8100164. Part of the work by one of us (R.D.H.) was also supported by the Office of Naval Research under contract NOC014-80-C-0293.
Energy,
M.
R. and
discharge
in motst au
1397
Gritfing G. W. (1977) Ozone and oxides of nitrogen production during thunderstorms. J. yrophJs. Res. 82. 943-950. Hill R. D.. Rinker NO, production 1077-1078.
R. G. and Wilson D. f 1978) Mechanism of by lightning. Trans. .dm. Geoph_vs. L’n. 59.
Hill R. D. (1979) On the production of nitric oxide by lightning. Geophys. Rrs. Left. 6, 945-947. Hill R. D., Rinker R. G. and Wilson H. D. (1980) Atmospheric nitrogen fixation by lightning. J. atmos. Sci. 37, 179-192. Hili R. D. and Rinker R. G (1981) Production of nitrateions and other trace species by lightnmg. J. grophxs. Res. 86, 3203-3209. Hill R. D., Rinker R. G. and Coucouvinos A. (1981) Nitrous oxide production by lightning. J. geophys. Res. 89, 141 l-1421. JANAF (1970) ThermodJnamicTables (2nd Edn). Publication NSRDSNBS37. U.S. National Bureau of Standards, Washington. D.C. Kok G. L. (1980) Measurements of hydrogen peroxide in rainwater. Atmospheric Encironment 14, 653-656. Kok G. L. ( I98 I) Measurements of hydrogen peroxide in the OSCAR Program. Report to Coordinating Research Council, Atlanta GA, NTIS-PB-82-256017. Levine J. S., Brooke R. R.. Shaw E. F. and Chameides W. L. (1981) Aircraft measurements of N20 enhancement in thunderstorm lightning. Trans. Am. Geophys. L’n. 62, 290. Levine J. S. and Shaw E. F. (1983) in situ aircraft measurements of enhanced levels of N,O associated with thunderstorm lightning. Nature, Land. 303, 312-314.
REFERENCES Balzhiser R E., Samuels Chemical Engineering
and corona
Eliassen
Thermodynamics: and Equilibrium.
J. D. (1972)
The
Study
of
Enrrop~, Prentice-Ha& Englewood Cliffs, NJ, pp. 506-527. Chameides W L., Stedmanb. H., Dickerson R. R., Rusch D. W. and Cicerone R. J. (197’7) NO, production in lightning. J. atmos. Sci. 34, 143-149. Chameides W. L. (1979) The implications of CO production in electrical discharges. Geophys. Res. Left. 6, 287-290. Coucouvinos A. (1983) Kinetic studies in ammonia synthesis. Nitrous oxide production by lightning. M.S. thesis, University of California, Santa Barbara, CA. Crowell B. A. (1980) Production of chemical species by lightning. M.S. thesis, University of California. Santa Barbara, CA. Donohoe K. G., Shair F. H. and WulfO. R. (1977) Production of 0s. NO and N,O in a pulsed discharge at I arm. Ind. Engng Chem. Fundnm. 16, 208-215. Ferguson E. E and Libby W. F. (1971) Mechanism for the fixation of nitrogen by lightning. Nature, Land. 229, 37.
Lin Y. T.. Uman M. A. and Standler R. B. (19801 Lightning return stroke models. J. geophys. Res. 85, 1571-1583. Penkett S. A.. Jones B. M. R.. Brice K. A. and Egglcton A. E. G. (1979) The importance of atmospheric ozone and hydrogen peroxide in oxidizing sulfur dioxide in cloud and rainwater. Atmospheric Erwironment 13, 123-I 37. Picone J. M.. Boris J. P., Greig J. R., Raleigh M. and Fernsler R. F. (1981) Convective cooling of lightning channels. J. atmos. Sci. 38, 20X-2062. Rahmin I. (1984) Production of trace species in atmospheric coronas. MS. thesis. University of California. Santa Barbara, CA. Tuck A. F. (1976) Production of nitrogen oxides by lightning. Q. Jl R. met. Sot. 102, 749-755. Zipf E. C. and Dubin M. (1976) Laboratory studies on the formation of NO, compounds and ozone by lightning.
Trans. Am. Geophys. Un. 51, 965. Zika R., Saltzman W. L., Chameides W. L. and Davis D. D. (1982) HtOr levels in rainwater collected in South Florida and the Bahama Islands. J. geophys. Res. 87, 3017-5017.