An ionometric counter for condensation nuclei

Summary Condensation nuclei detectable in the range of supersaturation used in the expansion method do not play the role expected earlier, for the production of water droplets in natural clouds.However, these nuclei exist in the atmosphere, and they can be of importance in other processes in the air; for example, they can be partners for annihilation of small air ions there. Therefore, a direct investigation of the interaction between the condensation nuclei and the small air ions may be of interest. For this purpose an, ionometric counter for condensation nuclei is designed, in which the air under examination is mixed in a mixing chamber with small air ions produced by a tritium ion-generator, and the presence of condensation nuclei is measured by the decrease of the concentration of air ions recorded with an aspiration ion counter as compared to the concentration recorded when filtered air was originally sucked through the mixing chamber.Comparatively rapid variations of the concentration of nuclei can be continuously recorded. The electrical properties of the aerosol particles destroying air ions can be investigated by inserting an electrical filter. By the ionometric counter condensation nuclei can be investigated without adding water particles to them.     

On some measurements of the condensation of different vapors upon Aitken condensation nuclei

No final theory on the activity of Aitken nuclei has been established yet. In particular the supersaturation is not known for the Aitken nuclei to grow into droplets, f.e. according toF. Volz only nuclei of radius >0.1 can cause condensation under atmospheric conditions. On the other hand according toH. G. Müller condensation over the continents has to occur at the Aitken nuclei since precipitation washes out the other nuclei.This uncertainty becomes obvious in the interpretation of the experimental results.Chr. Junge found that the necessary activation supersaturation of a continental Aitken aerosol and of artificial aerosols of the same size of nuclei lies between 2 and 20%, 10% being sufficient for the main fraction of nuclei to grow.In contrastW. Wieland was able to activate in a mixing cloud chamber a big portion, if not all, of the nuclei of a continental aerosol at supersaturations below 1.5%. Some of our own results, obtained with the same technic, agree with this. At supersaturations below 0.8% at least half of the Aitken nuclei present are activated. To obtain the same result with benzene and acetone we found, that benzene required a slightly smaller, and acetone a somewhat bigger supersaturation.However later experiments revealed a considerable effect of the geometry of the mixing cloud chamber upon the results. Since the physics of the chamber has not been fully explored the method was abandoned. Instead the principle of cooling by adiabatic expansion was used. An expansion apparatus based on the principle of a fotoelectric nucleus counter was developed allowing us to measure with two cathode ray oscillographs the pressure and simultaneously the change of intensity of a lightbeam due to the scattering on the forming cloud as a function of time. The length of the lightbeam could be chosen between 60 and 200 cm. The overpressure before the expansion was always 180 mm of mercury. The ratio of expansion rates was 12.53060 at the beginning of the expansion. The slowest rate was about 6 seconds, corresponding to a rate of ascent of 210 m/s at the beginning of the expansion. Smaller rates could not be obtained because of heat transfer at the chamber walls.The present work has been performed for the Eidgenössische Kommission zum Studium der Hagelbildung und der Hagelabwehr (Switzerland) at the research station Osservatorio Ticinese Locarno-Monti della Centrale Meteorologica Svizzera     

Measurement of lower-stratospheric aerosol by a balloon-borne photometer

Height distribution of the stratospheric aerosol extinction coefficient was measured in the altitude range 10 to 20 km by a balloon-borne multi-color sunphotometer in May 1978. It is demonstrated that detailed structures of the distribution of stratospheric aerosol can be remotely measured by the solar occultation method as well as by lidar andin situ particle counter observations. In the aerosol layer appearing at 18 km altitude the extinction coefficient at 800–1000 nm wavelength reached to 3×10^–7 m^–1, which was reasonable compared with lidar observations. Wavelength dependence of the aerosol optical depth was crudely estimated to be proportional to ^–1.5.     

Recombination rates of small ions and their attachment to aerosol particles

It could be shown by measurements of the air conductivity and using a mean profile for the ionization rate that experimental and theoretical values of the recombination rate of small ions based on a three body recombination process (Thomson) are in very good agreement up to 20 km altitude. The divergency of the experimental and theoretical curves above 20 km can be interpreted by assuming that there exists in this altitude region a crossover from the three body recombination to a two body recombination process. The value of the recombination coefficient is about 4·10^–7 cm³ s^–1 in 25 km altitude, compared with 1.4·10^–6 cm³ s^–1 at ground level. Furtheron it was possible for the first time to get some experimental data of attachment coefficients up to 13 km from simultaneous measurements of the air conductivity and Aitken nuclei concentration. These values are in good agreement with those obtained by theoretical considerations.     

Eine neue Methode der Kondensationskernzählung

Zusammenfassung In der vorliegenden Arbeit wird eine Methode beschrieben, die es gestattet, mit Hilfe lackierter Glasplatten Kondensationskerntröpfchen oder andere Tröpfchen mit einem Durchmesser von 5 zu fixieren und dann elektronisch auszuzählen. Vorversuche, bei denen diese Methode angewendet wurde, machen es wahrscheinlich, dass bei Kondensationskernzählern, die nach dem Expansionsprinzip arbeiten, ein Teil der Kerne wegen ihrer Aktivität schon vor der Expansion als Wassertröpfchen ausfällt und damit der Zählung entgeht.

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Summary In the present paper a method is described, which allows to fix droplets of condensation nucleus or other droplets (diameter 5 ) by means of varnished plates of glass and count them afterwards electronically. Preliminary experiments with this method show up the probability, that in the nucleus counter, working on the principle of expansion, some of the very active nucleus drops out before the expansion chamber is dilated and thus escapes registration.

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Riassunto Nella presente ricerca si descrive un metodo il quale consente di fissare goccioline provenienti da nuclei di condensazione, o altre goccioline (diam. 5 ), su dischi di vetro verniciati, e in seguito di contarle elettronicamente. Prove eseguite con questo metodo rendono probabile che, in contatori di nuclei di condensazione che lavorano secondo il principio dell'espansione, una parte dei nuclei, in seguito alla loro stessa attività, cada sotto forma di goccioline d'acqua già prima dell'espansione e che quindi sfugga al conteggio.

     

The concentration of molecular H2 and CH4 in the stratosphere

Stratospheric profiles of CH₄ and H₂ over eastern Texas have been derived up to 31 km altitude from air samples collected aboard a balloon and analyzed by gas chromatography. For H₂, contamination during flight and measurement presented a problem which has been resolved only recently. The earlier profiles require corrections which are rather large for the highest altitudes.The three profiles indicate an increase of the H₂ concentration in the lower stratosphere from about 0.5 p.p.m. per volume at the tropopause to about 0.8 p.p.m. at around 27 km altitude. Above that altitude the H₂ concentration decreases again. An air sample collected between 44 and 62 km by a rocket-borne cryogenic sampler had an H₂ concentration of 0.4 p.p.m.The five CH₄ profiles showed a decrease in CH₄ concentration with altitude generally with a steeper gradient directly above the tropopause and a weaker gradient at higher altitudes reaching 0.9 p.p.m. at 30 km altitude. The CH₄ concentration in the rocket sample was 0.25 p.p.m., in good agreement with the gradient obtained from the balloon samples.The National Center for Atmospheric Research is sponsored by the National Science Foundation.     

The transport and deposition of debris from nuclear test explosions

Fine debris from nuclear test explosions is removed from the atmosphere by dry deposition or by rainwater. The relative importance of these two mechanisms is considered and the conclusion is reached that, in middle latitudes, at least 80% of the fision product activity in soil has been brought down in rain. The average life of a small particle in the troposphere is deduced from the rate of decrease of air concentration and from the relation between air and rainwater activities and lies in the range 30–60 days. The factors influencing the attachment of a particle to a raindrop are discussed in the light of the most recent data and tentative conclusions are reached on the comparative efficiences of the three processes:

1. 1.
   Attachment to cloud droplets by Brownian motion.     
   
   

Versuch zur Charakterisierung atmosphärischer Kondensationskerne durch Koagulationsmessungen und durch Messungen bei verschiedenen Expansionen

Zusammenfassung Es wird versucht, örtliche und zeitliche Verschiedenheiten des Luftaerosols mit Hilfe von 2 Methoden zu erfassen:a) durch Koagulationsversuche bei einer in einem Ballon aufbewahrten Luftprobe durch regelmässige Messungen mit dem automatischen Kondensationskernzähler;b) durch Bestimmung der Kernzahl bei verschiedenen Expansionsdrucken während der Aufbewahrung einer Luftprobe. Solche Bestimmungen werden zur Zeit der maximalen nnd minimalen Kernzahl im Laufe eines Tages in Basel sowie in St. Moritz-Bad ausgeführt. Die Versuche sollen später, besonders vom meteorologischen Gesichtspunkt aus, ausgewertet werden.

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Summary The number of atmospheric condensation nuclei shows daily variations and also local differences. To test whether the nuclei are also different in quality and size two methods have been tried: Air was collected in a balloon and the coagulation followed by measuring the number of nuclei during 8 to 9 hours. Examples are given for air in Basel at 11 a.m. and at 4 a.m. Also differences are shown between the air in Basel (270 m) and St. Moritz-Bad at 1 800 m altitude. The coagulation of air samples was also studied with different expansion pressure up to 9 hours. All measurements were made with the automatic condensation nuclei counter. No definite conclusions are drawn but the value of these methods shall be studied expecially in connection with meteorological observations.

     

Distribution of airborne pollen and spores and their long distance transport

The atmosphere near the ground contains a mixed population of pollen and spores in the 1 to 90 m diameter range. Continuous sampling at Rothamsted Experimental Station at 2 m above ground level indicated concentrations averaging 12,000 m^–3 over 5 summer months, but 1 million m^–3 can occur for short periods. Concentrations change rapidly with locality, season, time of day or night and weather. Normally concentration in the troposphere decreases logarithmically with height. The occurrence of long distance transport of pollen and spores by wind is demonstrated by sampling from aircraft, and supported by much circumstantial evidence. Possible effects of this air spora on the atmosphere may be sought in alterations to: opacity, ionization, condensation nuclei, and sinks for minor gases.     

On sea-salt nuclei in the atmosphere

Summary The residues of cloud droplets collected at the summit of a mountain were examined with an electron microscope and their materials were identified with the aid of micro-electron-diffraction method. About 30% of nuclei of cloud droplets larger than 5 in radius were mainly composed of sodium chloride and their masses were 10^–1210^–13 gr. We also found salt particles in snow crystals. Some discussions are made about the process of the capture of these particles by snow crystals.     

Gravity anomaly and crustal density structure in Jilantai rift zone and its adjacent region

This paper deals with the interpretation of Bouguer gravity anomalies measured along a 250 km long Suhaitu-Etuokeqi gravity profile located at the transitional zone of the Alxa and Ordos blocks where geophysical characteristics are very complex. The analysis is carried out in terms of the ratio of elevation and Bouguer gravity anomaly, the normalized full gradient of a section of the Bouguer gravity anomaly (G ^h ) and the crustal density structure reveal that (1) the ratio of highs and lows of elevation and Bouguer gravity anomaly is large between Zhengyiguan fault (F4) and Helandonglu fault (F6), which can be explained due to crustal inhomogeneities related to the uplift of the Qinghai-Tibet block in the northeast; (2) the main active faults correspond to the G ^h contour strip or cut the local region, and generally show strong deformation characteristics, for example the Bayanwulashan mountain front fault (F1) or the southeast boundary of Alxa block is in accord with the western change belt of G ^h , a belt about 10 km wide that extends to about 30 km; (3) Yinchuan-Pingluo fault (F8) is the seismogenic structure of the Pingluo M earthquake, and its focal depth is about 15 km; (4) the Moho depth trend and Bouguer gravity anomaly variation indicates that the regional gravity field is strongly correlated with the Moho discontinuity.     

The seismic wave absorption in the crust and upper mantle in the vicinity of the Kislovodsk seismic station

The Q-factor estimates of the Earth’s crust and upper mantle as the functions of frequency (Q(f)) are obtained for the seismic S-waves at frequencies up to ~35 Hz. The estimates are based on the data for ~40 earthquakes recorded by the Kislovodsk seismic station since 2000. The magnitudes of these events are M_W > 3.8, the sources are located in the depth interval from 1 to 165 km, and the epicentral distances range from ~100 to 300 km. The Q-factor estimates are obtained by the methods developed by Aki and Rautian et al., which employ the suppression of the effects of the source radiation spectrum and local site responses in the S-wave spectra by the coda waves measured at a fixed lapse time (time from the first arrival). The radiation pattern effects are cancelled by averaging over many events whose sources are distributed in a wide azimuthal sector centered at the receiving site. The geometrical spreading was specified in the form of a piecewise-continuous function of distance which behaves as 1/R at the distances from 1 to 50 km from the source, has a plateau at 1/50 in the interval from 50–70 km to 130–150 km, and decays as \({\raise0.7ex\hbox{$1$} \!\mathord{\left/ {\vphantom {1 {\sqrt R }}}\right.\kern-\nulldelimiterspace} \!\lower0.7ex\hbox{${\sqrt R }$}}\) beyond 130–150 km. For this geometrical spreading model and some of its modifications, the following Q-factor estimates are obtained: Q(f) ~ 85f^0.9 at the frequencies ranging from ~1 to 20 Hz and Q(f) ~ 75f^1.0 at the frequencies ranging from ~1 to 35 Hz.     

Nitric oxide concentration near the mesopause as deduced from ionospheric absorption measurements

Nitric oxide concentration in the upper D-region is estimated by comparing empirically derived ratios of Lyman- and X-ray contributions to the total radio-wave absorption (2775 kHz. A3 method) in medium latitudes with model ratios. Typical NO concentrations are about 8.5×10¹³ m^–3, at 90 km and 6.5×10¹³ m^–3 at 78 km. These values are higher than generally accepted model NO concentrations, but lie within the broad range of experimental values.     

Behavior of Parameters of Enhancements in the Nighttime Electron Concentration in the Ionospheric <Emphasis Type="Italic">F</Emphasis>2 Layer

We have analyzed the behavior of the F2 layer parameters during nighttime periods of enhanced electron concentration by the results of vertical sounding of the ionosphere carried out with five-minute periodicity in Almaty (76°55′ E, 43°15′ N) in 2001–2012. The results are obtained within the frameworks of the unified concept of different types of ionospheric plasma disturbances manifested as variations in the height and half-thickness of the layer accompanied by an increase and decrease of N _m F2 at the moments of maximum compression and expansion of the layer. A good correlation is found between height h _Am , which corresponds to the maximum increase, and layer peak height h _m F, while h _Am is always less than h _m F. The difference between h _Am and h _m F linearly increases with increasing h _m F. Whereas the difference is ~38 km for h _m F = 280 km, it is ~54 km for h _m F = 380 km. Additionally, the correlation is good between the increase in the electron concentration in the layer maximum ΔN _m and the maximum enhancement at the fixed height ΔN; the electron concentration enhancement in the layer maximum is about two to three times lower than its maximum enhancement at the fixed height.     

Dynamics of the midlatitude ionospheric <Emphasis Type="Italic">F</Emphasis> region at sunrise

The behavior of the F2 layer at sunrise has been studied based on vertical-incidence ionospheric sounding data in Almaty (76°55′E, 43°15′N). Records with small amplitudes of electron density background fluctuations were selected in order to exactly estimate the onsets of a pronounced increase in the electron density at different altitudes. It has been indicated that the electron density growth rate is a function of altitude; in this case, the growth rate at the F2 layer maximum is much lower than such values at fixed altitudes of ～30–55 km below the layer maximum. The solar zenith angle (χ) and the blanketing layer thickness (h ₀) at the beginning of a pronounced increase in the electron density at altitude h are linearly related to the h value, and these quantities vary within ～90° < χ < 100° and 180 km < h ₀ < 260 km, respectively.     

Spectrum of quasi-wave disturbances in the topside daytime ionosphere according to the data of radiosounding onboard the Intercosmos-19 satellite

Quasi-wave disturbances in the topside daytime ionosphere, related to auroral activity, have been detected using the data of radiosounding onboard the Intercosmos-19 satellite on April 28, 1979. A disturbance was caused by an abrupt enhancement of the eastward electrojet, which was not reflected in the variations in the AE and AU indices. According to the estimates, the period of electron density disturbances was about 0.5 h, the velocity was 350 m/s, and the length along the meridian was several hundreds of kilometers, which corresponds to medium-scale traveling ionospheric disturbances (TIDs). The disturbance amplitude was only 30 km in the hmF2 variations and 0.20–0.25 MHz in the foF2 variations but increased to 0.25–0.30 MHz in the plasma frequency variations at satellite altitudes of 520–580 km with increasing altitude. It is impossible to register so weak short-period variations during ground-based sounding. The method for detecting disturbance spatial characteristics has been proposed. The disturbance spectrum including three quasiperiodic structures has been revealed using this method. The optimal estimates have been made for the trend, described by the polynomial of the third degree, and for the expansion of the residuals in terms of three harmonics.     

Small ion concentrations in and near clouds and fogs

Summary A mobile small ion and condensation nuclei laboratory was used to study small ion concentrations in and near orographic clouds, low cloud bases, and fogs. It was found that these areas of diminished visibility exist in a conductivity well, characterized by a small ion concentration of less than 200 small ions per cm³, surrounded by an area of increasing small ion concentration, until the concentration exceeds 400 small ions per cm³ 500 to 1000 feet below the base of the cloud. It was also observed that small ion concentration increases during the dissipation of fog, and oscillates with the passage of large patches of drifting fog.     

The role of the SO2 oxidation for the background stratospheric sulfate layer in the light of new reaction rate data

Presently available data on the reaction of SO₂ with OH radicals (OH + SO₂ + \(M\xrightarrow[{k_1 }]{}\) HSO₃ +M) are critically reviewed in light of recent stratospheric sulfur budget calculations. These calculations impose that the net oxidation ratek of SO₂ within the stratosphere should fall within the range 10^?7≤k≤10^?9, if the SO₂ oxidation model for the stratospheric sulfate layer is assumed to be correct. The effective reaction rate constantk ₁ ^* =k ₁[M] at the stratospheric temperature is estimated as $$k_1^* = \frac{{(8.2 \pm 2.2) \times 10^{ - 13} \times [M]}}{{(0.79 \mp 0.34) \times 10^{ - 13} + [M]}}cm^3 /molecules sec$$ where [M] refers to the total number density (molecules/cm³). Using the above limiting values ofk ₁ ^* , and the estimated OH density concentrations, the net oxidation rate is calculated as 3.6×10^?7≤k≤1.3×10^?8 at 17 km altitude. This indicates that the upper limit of thesek values exceeds the tolerable range imposed by the model by a factor of about four. Obviously the uncertainty of thek ₁ ^* values and of the OH concentrations in the stratosphere is still too large to make definite conclusions on the validity of the SO₂ model.     

Relation between concentrations of giant chloride nuclei and exchange in the atmosphere

Summary In Northern Bohemia 33 research flights were made during which concentration of giant condensation chloride nuclei was measured up to a height of 3,500 m above the earth's surface. Chloride particles were determined by traces left by them in a sheet of gelatine with silver nitrate (Liesegang circles). The actual size of the particles was obtained by comparison of particles of a known size, falling in a sedimentation tube, with images in the sensitive sheet, and the result was adapted to the analysis of samples during the flight. For each level at which a sample was exposed the spectrum of the sizes of nuclei was determined. During the year the average concentration of the giant chloride nuclei at a height of 100 m above the earth was 7.3×10^–3 cm^–3. At greater heights concentration of the nuclei decreased successively, so that at 2,000 m it was only 0.3×10^–3 cm^–3 and above the level of 3,000 m the nuclei occurred sporadically, on the whole. Under the influence of atmospheric exchange the concentration of the nuclei in the boundary layer up to 1,000 m above the earth's surface changes considerably both during the day and during the year. The highest concentration occurs at a height of several hundred metres above the earth in the winter month, at the morning and evening hours, i.e. during a more stable temperature lapse rate. From the established concentrations of the nuclei relation between the turbulent diffusion coefficient and the height above the earth was determined. Its average value during the year increases up to a height of 300 to 400 m above the earth. Above this level it decreases roughly according to the relation ofKz ^–6/7. The exponent changes not only with temperature stratification (with the time of day and year), but also with the average wind speed. For sodium-chloride particles of 2.5 in diameter the maximum value of turbulent diffusion coefficient (at level of 400 m), reaches about 18×10³ cm² sec^–1 while the minimum value is about 5×10³ cm² sec^–1 (above 2,000 m).     

The role of sodium bicarbonate in the nucleation of noctilucent clouds

It is proposed that a component of meteoric smoke, sodium bicarbonate (NaHCO₃), provides particularly effective condensation nuclei for noctilucent clouds. This assertion is based on three conditions being met. The first is that NaHCO₃ is present at sufficient concentration (10⁴ cm^–3) in the upper mesosphere between 80 and 90 km. It is demonstrated that there is strong evidence for this based on recent laboratory measurements coupled with atmospheric modelling. The second condition is that the thermodynamics of NaHCO₃(H₂O)_n cluster formation allow spontaneous nucleation to occur under mesospheric conditions at temperatures below 140 K. The Gibbs free energy changes for forming clusters with n = 1 and 2 were computed from quantum calculations using hybrid density functional/Hartree-Fock (B3LYP) theory and a large basis set with added polarization and diffuse functions. The results were then extrapolated to higher n using an established dependence of the free energy on cluster size and the free energy for the sublimation of H₂O to bulk ice. A 1-dimensional model of sodium chemistry was then employed to show that spontaneous nucleation to form ice particles (n > 100) should occur between 84 and 89 km in the high-latitude summer mesosphere. The third condition is that other metallic components of meteoric smoke are less effective condensation nuclei, so that the total number of potential nuclei is small relative to the amount of available H₂O. Quantum calculations indicate that this is probably the case for major constituents such as Fe(OH)₂, FeO₃ and MgCO₃.