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On the remarks of V.I. Krassovsky regarding the O3 and O2∗ hypotheses of the OH airglow
:Research notes
The sodium-vapour detector records emission even in early twilight, and therefore the Fraunhofer correction must be determined in the daytime. However, this very fact means that the correction is small, and DONAHUE'S effect must be even smaller. The best procedure would be to make the determination just before sunset on direct sunlight (attenuated, of course) rather than on sky light, which might still show an appreciable emission component. The appearance of raw obserw~tions without the Fraunhofer correction may be of interest. Two such runs have been published by BLAMONT and KASTLER (1951); they were taken with a quartz birefringent filter. Negative intensities are shown ibr early twilight; the authors explained the reason, but did not attempt to make a correction, probably because they had no record of the white-light intensity. Our own results behave in nmch the same way; the apparent intensity is about 10 per cent low dm'ing the main part of the twilight, but falls much lower in the early part, going negative when the solar depression is less than about 4030 '. With the correction included, n,) drop in intensity has ever 1)een found in about one-hundred examples, although the scatter of the points is often large, because the correction gives nearly the whole result. A good example of a corrected run has been published by HUNTEN and SHEPHERD (1954, Fig. 3). The observations published 1)y ]~LAMON-T(1956) were made with the s()dium-wqJom" detector and have had no Fraunhofer correction applied. There are indications flint it is negligible as long as the solar depression is greater than about 5°, but f(,r smaller angles it may be ~ppreciable. We hope to make a closer study of the question in cooperation with BLAMONT, who has been most generous with his data and in discussion. In addition, we should like to acknowledge discussions and correspondence with CHAMBERLAINand DONAHUE; the latter also kindly sent a copy of his i)aper before it was published. D. M. HUNTEN University of Saskatchewan, Saskatoon, Canada REFERENCES BLAMONT J . E. 1953 C. R. Acad. Sci. Paris. 237, 1320. 1956 The Airglow and the Aurorae (Edited by :B. E. ARMSTRONGand A. DALGAR-~O)D" 99. Pergamon Press, London. BLAMONTJ. E. andKASTLER A. 1951 Ann. Gdophys. 7, 73. DO~AHUE T . M . 1956 J. Atmosph. Terr. Phys. 9, 262. 1956 The Airglow and the Aurorae (F,d. E. B. HARRISON A. W. and .~RMSTRO~NG and A. DAL(;AR.N-O) t). 95. VALLANCEJONES A. Pergamon Press. HUNTEN D. ~/[. a n d SHEPHERD G. G. 1954 J. Atmosph. Terr. Phys. 5, 57. 1956 Nature, Lond. 178, 753. SCRIMGER J. A. a n d HUNTEN D. M.
On the remarks of V. I. Krassovsky regarding the 03 and 0~* hypotheses o~ the OH airglow (Received 28 March 1957)
KRASSOVSKY (1957) claims that tlle rocket investigations of KOOMEN, SCOLNIK, and TOUSE¥ (1956) on the nocturnal radiation near 5300 ~ have established that the Meinel 68
Research notes
hydroxyl emission originates from about the 100 km level. This claim is unjustified. Thus, KOOME~ et al. state: " Some of the [5300] radiation m a y be from OH, though the 9-2 and 6-0 bands were located well away from the wavelength of m a x i m u m transmission ()f the filter." Again, HU~AERTS and NICOLET (1950) do not, as asserted by KRASSOVSK¥, suppose that the 5300 A radiation consists of the 9-2 and 6-0 b a n d s - - t h e y merely point out that these bands are present. Their intensity is in fact low (of. BA~mER, DVFAY, and WILHAMS, 1951; BARmEn, 1956). In the remainder of his note, K~ASSOVSKY contests the views put forward by us (BATES and MOISEIWITSCm 1956). We shall not take space by reiterating our arguments, but there are several points on which comment is desirable, since nfisunderstanding aI)pears to have arisen. (i) The excitation of the tenth vibrational level of OH by 0 a + H - * ()~ + OH*
(I)
requires the availability of about 5 keal of kinetic energy/mole and therefore cannot occur to an observable extent at ordinary temperatures. Further, the studies of GARVlN and McKINLEY (1956) confirm t h a t the activation energy of (1) is low, as assumed by BATES and NICOLET (1950)--indeed, its value appears to be less than 3 keal/mole.~ (ii) KRASSOVSK¥ takes the rate coefficient of 0 + O 2 + M--~ 0 a + M
(2) to be 10 -a3 T~ em6/see, as estimated by ENI~OLOPJA~ and NALBA~DJAN (1950). This is approximately the gas kinetic value and hence seems to us improbably large. ENIKOLOPJA~ and NALBA~DJA~ obtained their estimate by a very indirect method. Their work provides no justification for discarding the value based on the measurements of E~CKE~ and PATAT (1936). (iii) There is no inconsistency in using different effective solar temperatures when considering the two rival hypotheses. I t is necessary to do so, since the O a hypothesi~ depends mainly on photo-dissociation by the tterzberg continuum deep in the atmosphere: whereas the O2" hypothesis depends mainly o~t photo-dissociation by the Schumann-Run(.te continuum high in the atmosphere. Rocket scientists (ef. F~IEI)MA~, 1956) find t h a t the effective solar temperature is a rapidly decreasing function of the frequency in the spectral region concerned. (iv) Deactivation by the atom-atom interchange process calmot be dismissed on the grounds t h a t the process "need not necessarily be accompanied by a change of vibrational quantmn nmnber," since there is no reason why collisions ill which this quantum number is preserved should be favoured.++ D. R. BATES Department of Applied Mathematics, B. L. MOISEIWlTSCI[ The Queen's Unicersity of Belfast 1)~EFERENCES
BATES D. R. and MOISEI'WITSCHB.L. BATES D. R. and NICOLET M.
1956 1950
BARBIER D .
1956 1951
BARBIER D., DUFAY ,]., a n d WILLIAMS D . R .
J. Atmosph. Terr. Phys. 8, 305. J. Geophys. Res. 55, 301. Ann. Gdopkys. 11, 67.§ Ann. Astrophys. 14, 399.¶i
? P r i v a t e c o m m u n i c a t i o n (Dr. McKinley). W e did n o t m i s q u o t e KRASSOVSKY'S e s t i m a t e of t h e half-life of a t o m i c o x y g e n at 70 kin, as his final f o o t n o t e s u g g e s t s - - t h e e r r o n e o u s value, 5 sec, a p p e a r s in his p a p e r s (KRAssovsKY, 1954, 1956). As r e g a r d s t h e critical v i b r a t i o n a l q u a n t u m n u m b e r s of O2", t h e v a l u e s 25 a n d 26 result f r o m a (alculalion b y us, u s i n g a n e x p r e s s i o n g i v e n b y CLrRRY a n d HERZBERG (1934). § See, in p a r t i c u l a r , p. 75 et 8eq. ¶ See, in p a r t i c u l a r , p. 428.
5A
69
l~esearch notes CurRY J. and HERZBERG G. ENIKOLOPJANN. S. and NALBANDJANA.B.
1934 1950
EUCKEN A. a n d PATAT F. FRIEDMAN H. HUNAERTS J. and NICOLET M. KOOMEN M., SeOLNIK R., and TOUSEY 1£. KRASSOVSKY V, I. KrCASSOVSKY V. i.
1936 1956 1956 1950 1956 1954 1956
KRASSOVSKY V. [.
1957
G~WN D. and McKINLEY J. D.
Ann. Phys. Lpz. 19, 8O0. The Kinetics of Chain Oxidation Reactions. (Ed. by A. B. NALBA~DJA~ and N. M. AMA~OUEL) p. 38. Publishing House of the Acad. of Sciences, U.S.S.R. Z. Phys. Chem. 33, 459. Ann. Gdophys. 11, 60. J. Chem. Phys. 24, 1256. Ciel et Terre 66, 213. J. Geophys. Res. 61, 304. Dokl. (U.S.,8'.R.) 99, 979. The Airglow and the Aurora(', (E(t. by E. B. ARMSTRONGand A. DALGAR=~O) p. 197. Pergamon Press, London. J. Atmosph. 7'err. l'hy~'. 10, 49.
Nuclear explosions and a possible secular variation oi the potential gradient in the atmosphere (Received 2 M a y 1957)
T~E fair-weather aspects of atmospheric electricity may be considered as resulting from two factors. The first is the presence of a conducting or "equalizing" layer, at a height H in the atmosphere, which is maintained at a potential VIt , with respect to the earth, by the action of thunderstorms. Secondly, as a result of certain ionizing radiations, the air between the equalizing layer and the ground is a conductor. An air-earth current therefore flows whose magnitude is independent of height, since there is no accumulation of chargc at any point. The resistance, R H, of a column of air of unit cross-section extending from the ground to the equalizing layer is given by
/,
where ~h is the local conductivity at height h; the local potential gradient, F/~, at the same level may be written as Vu. 1 F,~- RH ~, (2) The suffix h m a y now be dropped, it being understood, however, that ). and F vary with height. The conductivity is due to the ionization present, and .~ ~ nikie i
(3)
where ni, ki, and ei, are respectively the number per unit volume, the mobility, and charge, of ions of a particular kind; the smrmlation is to cover all the ions present. Near the ground, two main kinds of ion, the large and the small, exist. The concentration of the small ions is perhaps only a tenth of the corresponding figure for large ions, but the small-ion mobility is about 104 times as great as that of large ions; hence the conductivity is almost entirely 70
The sodium-vapour detector records emission even in early twilight, and therefore the Fraunhofer correction must be determined in the daytime. However, this very fact means that the correction is small, and DONAHUE'S effect must be even smaller. The best procedure would be to make the determination just before sunset on direct sunlight (attenuated, of course) rather than on sky light, which might still show an appreciable emission component. The appearance of raw obserw~tions without the Fraunhofer correction may be of interest. Two such runs have been published by BLAMONT and KASTLER (1951); they were taken with a quartz birefringent filter. Negative intensities are shown ibr early twilight; the authors explained the reason, but did not attempt to make a correction, probably because they had no record of the white-light intensity. Our own results behave in nmch the same way; the apparent intensity is about 10 per cent low dm'ing the main part of the twilight, but falls much lower in the early part, going negative when the solar depression is less than about 4030 '. With the correction included, n,) drop in intensity has ever 1)een found in about one-hundred examples, although the scatter of the points is often large, because the correction gives nearly the whole result. A good example of a corrected run has been published by HUNTEN and SHEPHERD (1954, Fig. 3). The observations published 1)y ]~LAMON-T(1956) were made with the s()dium-wqJom" detector and have had no Fraunhofer correction applied. There are indications flint it is negligible as long as the solar depression is greater than about 5°, but f(,r smaller angles it may be ~ppreciable. We hope to make a closer study of the question in cooperation with BLAMONT, who has been most generous with his data and in discussion. In addition, we should like to acknowledge discussions and correspondence with CHAMBERLAINand DONAHUE; the latter also kindly sent a copy of his i)aper before it was published. D. M. HUNTEN University of Saskatchewan, Saskatoon, Canada REFERENCES BLAMONT J . E. 1953 C. R. Acad. Sci. Paris. 237, 1320. 1956 The Airglow and the Aurorae (Edited by :B. E. ARMSTRONGand A. DALGAR-~O)D" 99. Pergamon Press, London. BLAMONTJ. E. andKASTLER A. 1951 Ann. Gdophys. 7, 73. DO~AHUE T . M . 1956 J. Atmosph. Terr. Phys. 9, 262. 1956 The Airglow and the Aurorae (F,d. E. B. HARRISON A. W. and .~RMSTRO~NG and A. DAL(;AR.N-O) t). 95. VALLANCEJONES A. Pergamon Press. HUNTEN D. ~/[. a n d SHEPHERD G. G. 1954 J. Atmosph. Terr. Phys. 5, 57. 1956 Nature, Lond. 178, 753. SCRIMGER J. A. a n d HUNTEN D. M.
On the remarks of V. I. Krassovsky regarding the 03 and 0~* hypotheses o~ the OH airglow (Received 28 March 1957)
KRASSOVSKY (1957) claims that tlle rocket investigations of KOOMEN, SCOLNIK, and TOUSE¥ (1956) on the nocturnal radiation near 5300 ~ have established that the Meinel 68
Research notes
hydroxyl emission originates from about the 100 km level. This claim is unjustified. Thus, KOOME~ et al. state: " Some of the [5300] radiation m a y be from OH, though the 9-2 and 6-0 bands were located well away from the wavelength of m a x i m u m transmission ()f the filter." Again, HU~AERTS and NICOLET (1950) do not, as asserted by KRASSOVSK¥, suppose that the 5300 A radiation consists of the 9-2 and 6-0 b a n d s - - t h e y merely point out that these bands are present. Their intensity is in fact low (of. BA~mER, DVFAY, and WILHAMS, 1951; BARmEn, 1956). In the remainder of his note, K~ASSOVSKY contests the views put forward by us (BATES and MOISEIWITSCm 1956). We shall not take space by reiterating our arguments, but there are several points on which comment is desirable, since nfisunderstanding aI)pears to have arisen. (i) The excitation of the tenth vibrational level of OH by 0 a + H - * ()~ + OH*
(I)
requires the availability of about 5 keal of kinetic energy/mole and therefore cannot occur to an observable extent at ordinary temperatures. Further, the studies of GARVlN and McKINLEY (1956) confirm t h a t the activation energy of (1) is low, as assumed by BATES and NICOLET (1950)--indeed, its value appears to be less than 3 keal/mole.~ (ii) KRASSOVSK¥ takes the rate coefficient of 0 + O 2 + M--~ 0 a + M
(2) to be 10 -a3 T~ em6/see, as estimated by ENI~OLOPJA~ and NALBA~DJAN (1950). This is approximately the gas kinetic value and hence seems to us improbably large. ENIKOLOPJA~ and NALBA~DJA~ obtained their estimate by a very indirect method. Their work provides no justification for discarding the value based on the measurements of E~CKE~ and PATAT (1936). (iii) There is no inconsistency in using different effective solar temperatures when considering the two rival hypotheses. I t is necessary to do so, since the O a hypothesi~ depends mainly on photo-dissociation by the tterzberg continuum deep in the atmosphere: whereas the O2" hypothesis depends mainly o~t photo-dissociation by the Schumann-Run(.te continuum high in the atmosphere. Rocket scientists (ef. F~IEI)MA~, 1956) find t h a t the effective solar temperature is a rapidly decreasing function of the frequency in the spectral region concerned. (iv) Deactivation by the atom-atom interchange process calmot be dismissed on the grounds t h a t the process "need not necessarily be accompanied by a change of vibrational quantmn nmnber," since there is no reason why collisions ill which this quantum number is preserved should be favoured.++ D. R. BATES Department of Applied Mathematics, B. L. MOISEIWlTSCI[ The Queen's Unicersity of Belfast 1)~EFERENCES
BATES D. R. and MOISEI'WITSCHB.L. BATES D. R. and NICOLET M.
1956 1950
BARBIER D .
1956 1951
BARBIER D., DUFAY ,]., a n d WILLIAMS D . R .
J. Atmosph. Terr. Phys. 8, 305. J. Geophys. Res. 55, 301. Ann. Gdopkys. 11, 67.§ Ann. Astrophys. 14, 399.¶i
? P r i v a t e c o m m u n i c a t i o n (Dr. McKinley). W e did n o t m i s q u o t e KRASSOVSKY'S e s t i m a t e of t h e half-life of a t o m i c o x y g e n at 70 kin, as his final f o o t n o t e s u g g e s t s - - t h e e r r o n e o u s value, 5 sec, a p p e a r s in his p a p e r s (KRAssovsKY, 1954, 1956). As r e g a r d s t h e critical v i b r a t i o n a l q u a n t u m n u m b e r s of O2", t h e v a l u e s 25 a n d 26 result f r o m a (alculalion b y us, u s i n g a n e x p r e s s i o n g i v e n b y CLrRRY a n d HERZBERG (1934). § See, in p a r t i c u l a r , p. 75 et 8eq. ¶ See, in p a r t i c u l a r , p. 428.
5A
69
l~esearch notes CurRY J. and HERZBERG G. ENIKOLOPJANN. S. and NALBANDJANA.B.
1934 1950
EUCKEN A. a n d PATAT F. FRIEDMAN H. HUNAERTS J. and NICOLET M. KOOMEN M., SeOLNIK R., and TOUSEY 1£. KRASSOVSKY V, I. KrCASSOVSKY V. i.
1936 1956 1956 1950 1956 1954 1956
KRASSOVSKY V. [.
1957
G~WN D. and McKINLEY J. D.
Ann. Phys. Lpz. 19, 8O0. The Kinetics of Chain Oxidation Reactions. (Ed. by A. B. NALBA~DJA~ and N. M. AMA~OUEL) p. 38. Publishing House of the Acad. of Sciences, U.S.S.R. Z. Phys. Chem. 33, 459. Ann. Gdophys. 11, 60. J. Chem. Phys. 24, 1256. Ciel et Terre 66, 213. J. Geophys. Res. 61, 304. Dokl. (U.S.,8'.R.) 99, 979. The Airglow and the Aurora(', (E(t. by E. B. ARMSTRONGand A. DALGAR=~O) p. 197. Pergamon Press, London. J. Atmosph. 7'err. l'hy~'. 10, 49.
Nuclear explosions and a possible secular variation oi the potential gradient in the atmosphere (Received 2 M a y 1957)
T~E fair-weather aspects of atmospheric electricity may be considered as resulting from two factors. The first is the presence of a conducting or "equalizing" layer, at a height H in the atmosphere, which is maintained at a potential VIt , with respect to the earth, by the action of thunderstorms. Secondly, as a result of certain ionizing radiations, the air between the equalizing layer and the ground is a conductor. An air-earth current therefore flows whose magnitude is independent of height, since there is no accumulation of chargc at any point. The resistance, R H, of a column of air of unit cross-section extending from the ground to the equalizing layer is given by
/,
where ~h is the local conductivity at height h; the local potential gradient, F/~, at the same level may be written as Vu. 1 F,~- RH ~, (2) The suffix h m a y now be dropped, it being understood, however, that ). and F vary with height. The conductivity is due to the ionization present, and .~ ~ nikie i
(3)
where ni, ki, and ei, are respectively the number per unit volume, the mobility, and charge, of ions of a particular kind; the smrmlation is to cover all the ions present. Near the ground, two main kinds of ion, the large and the small, exist. The concentration of the small ions is perhaps only a tenth of the corresponding figure for large ions, but the small-ion mobility is about 104 times as great as that of large ions; hence the conductivity is almost entirely 70