bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of conductive polybenzoxazines by oxidative polymerization
Authors: Kiskan Baris , Yagci Yusuf , Sahmetlioglu Ertugrul , Toppare Levent
Published: February 2007

Soluble and thermally curable conducting high molecular weight polybenzoxazine precursors were prepared by oxidative polymerization 3‐phenyl‐3,4‐dihydro‐2H‐benzo[e][1,3] oxazine (P‐a) alone and in the presence of thiophene (Th) with ceric ammonium nitrate in acetonitrile. The structure of the precursors was confirmed by FTIR, 1H NMR, and DSC measurements, indicating the presence of a cyclic benzoxazine structure, together with small but varying amount of a ring opened phenolic structure. The resulting polymers exhibit conductivities around 10−2 S cm−1 and undergo thermal curing at various temperatures. Attempts to copolymerize P‐a with another electroactive monomer, pyrrole (Py), by a similar redox process were unsuccessful, which was attributed to the unfavourable oxidation potential of Py. The cured products exhibited high thermal stability but lower conductivity, than those of the precursors. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 999–1006, 2007
Gas solubility of carbon dioxide in poly(lactic acid) at high pressures: Thermal treatment effect
Authors: Oliveira N. S. , Dorgan J. , Coutinho J. A. P. , Ferreira A. , Daridon J. L. , Marrucho I. M.
Published: January 2007

The sorption of carbon dioxide in glassy Poly(lactic acid) (PLA) films was studied by quartz crystal microbalance (QCM) at high pressures. Two thermal treatments, melted and quenched, were performed in PLA with two different L:D contents, 80:20 and 98:2, films and compared with a third thermal protocol, annealed, and used in a previous work. The results obtained show that for pressures higher than 2 MPa, the carbon dioxide solubility is larger in PLA 80:20 than in PLA 98:2, indicating that the L:D plays a dominant role on this property. The thermal treatments only affect the gas solubility in PLA 98:2. Sorption isotherms at temperatures 303, 313, and 323 K, below the glass transition temperature of the polymer, and pressures up to 5 MPa were measured and analyzed with three different models, the dual‐mode sorption model, the Flory–Huggins equation, and a modified dual‐mode sorption model where the Henry's law term was substituted by the Flory–Huggins equation. This last model performs especially well for CO2 in PLA 80:20, due to the convex upward curvature of the solubility isotherms for that system. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 616–625, 2007
Wide angle X‐ray diffraction and Fourier transform infrared dichroism studies of stretched‐recovery‐restretched process of polyurethane/clay nanocomposite
Authors: Chen Guangming , Ma Yongmei , Zheng Xianjun , Xu Guangyang , Liu Jun , Fan Jiaqi , Shen Deyan , Qi Zongneng
Published: February 2007

An intercalated polyurethane (PU) /clay nanocomposite was prepared by in situ intercalative polymerization. The PU/clay nanocomposite pellet or film samples were stretched‐recovery‐restretched, using selfmade microstretching tools. The changes of the basal spacings of clay and the orientation of polymer chain segments during the stretched‐recovery‐restretched process were studied by wide angle X‐ray diffraction (WAXD) and Fourier transform infrared (FTIR) dichoism techniques. The WAXD results show that the basal spacing of clay did not change obviously, indicating that no macromolecular chains entered or moved out of the interlayer space, and the orientations of both hard and soft segments inside the interlayer space did not change obviously, either. The FTIR dichroism tests suggest that outside the interlayer space, the orientation of the hard chain segment increased, decreased, and then increased again during the stretched‐recovery‐restretched process. However, no obvious changes of the degree of orientation of the soft segment were observed during the processes, the slightly orientation might be released during the relaxation process before the measurements. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 654–660, 2007
Differential retention of α‐vitamin E is correlated with its transporter gene expression and growth inhibition efficacy in prostate cancer cells
Authors: Ni Jing , Pang See‐Too , Yeh Shuyuan
Published: January 2007

BACKGROUND

Epidemiological studies showed Vit E has protective effects against prostate cancer (PCa). Interestingly, different prostate cancer cells have different sensitivity to α‐Vit E or VES treatment. The goal of this study is to determine whether cellular Vit E bioavailability and its transport proteins are important contributing factors.

METHODS

α‐Vit E and its ester form, VES, were used to treat prostate cancer LNCaP, PC3, and DU145 cells, and their growth rates were determined by MTT assay. Cellular levels of Vit E were quantified using HPLC as the index of bioavailability. The expression levels of Vit E transport proteins were determined by real‐time PCR.

RESULTS

Among these PCa cells, only LNCaP cells were sensitive to 20 µM α‐Vit E treatment, while both LNCaP and PC3 cells were sensitive to 20 µM VES treatment. Coordinately, cellular levels of α‐Vit E and VES positively correlated to their inhibitory effects. Further study found expression levels of Vit E transport proteins, including tocopherol associated protein (TAP), scavenger receptor class B type I (SR‐BI), α‐tocopherol transfer protein (TTP), and ATP binding cassette transporter A1 (ABCA1), were different in various PCa cells, which may contribute to cellular Vit E bioavailability. This notion is further supported by the findings that overexpression or knockdown of TTP could coordinately alter cellular α‐Vit E levels in PCa cells.

CONCLUSION

Antiproliferative efficacy of α‐Vit E is correlated with its cellular bioavailability in PCa cells. Modulating the expression of the efflux or influx transporters could sensitize the growth inhibition efficacy of Vit E in prostate cancer cells. Prostate 67: 463–471, 2007. © 2007 Wiley‐Liss, Inc.
The influence of antimony on the optical quality of highly strained GaInNAs/GaAs QWs investigated by contacless electroreflectance
Authors: Kudrawiec R. , Yuen H. B. , Bank S. R. , Bae H. P. , Wistey M. A. , Harris James S. , Motyka M. , Gladysiewicz M. , Misiewicz J.
Published: February 2007

Contactless electroreflectance (CER) has been applied to study the influence of Sb atoms on the optical quality of highly strained GaInNAs/GaAs quantum wells (QWs). A set of QWs grown under various antimony fluxes has been analyzed in this work. The broadening of the CER resonance has been used as an indicator of the QW quality. It has been observed that broadening of the CER resonance related to the ground state transition decreases about three times (from ∼60 meV to 20 meV) after the incorporation of antimony into GaInNAs/GaAs QWs. Moreover, it has been observed that the broadening parameter does not decrease with the rise of antimony content from 0.5% to 2.0%. It means that only 0.5% Sb is enough to improve the optical quality of GaInNAs/GaAs QWs. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modulation spectroscopy on a single self assembled quantum dot
Authors: Seidl S. , Högele A. , Kroner M. , Karrai K. , Warburton R. J. , Garcia J. M. , Petroff P. M.
Published: February 2007

We present high resolution modulation spectroscopy on single quantum dots and discuss briefly the differences to other spectroscopy techniques. We use this technique to study the excitonic fine structure while charging the quantum dot and applying mechanical strain to it. We also show that the fine structure can be used as a polarization analyzer. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Contactless modulated reflectivity of quasi 0D self‐assembled semiconductor structures
Authors: Sęk G. , Kudrawiec R. , Motyka M. , Poloczek P. , Rudno‐Rudziński W. , Podemski P. , Misiewicz J.
Published: February 2007

Two different approaches of contactless modulated reflectivity spectroscopy, namely photoreflectance (PR) and contactless electroreflectance (CER), have been used for the investigation of quasi 0D self‐assembled semiconductor structures, like quantum dots or quantum dashes. First of all, the advantages and disadvantages of both techniques are discussed with respect to that certain application, including the problems of spurious background signals and below‐band‐gap oscillations. Second, the modulation mechanism in photoreflectance of quantum dots is analyzed by comparing PR, CER, photoluminescence excitaion and photoreflectance excitation. Finally, recent results regarding the modulation spectroscopy study of several types of structures including quasi 0D objects will be presented. It will concern the following aspects in particular: wetting layer (WL) thickness determination; quantum dots formation at the 2D–3D Stranski–Krastanov growth transition for the case of Inx Ga1–x As/GaAs quantum dots; probing the excited states and electronic structure in novel material/design QDot/QDash systems and characterization of the QD‐based laser structures. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The application to micrometeorology of the theory of turbulent flow over rough surfaces
Authors: Sutton O. G.
Published: February 2007

It is now well established that turbulent flow near the surface of the earth is usually of the type known as “aerodynamically rough”, and the present paper discusses the implications of this for diffusion. The various theories of rough flow are discussed and the conclusion reached that the formulation due to Rossby and Montgomery, in which the influence of the surface irregularities dies out with height, is the treatment most appropriate for meteorology, because of the relatively great depth of the layers dealt with as compared with wind tunnel boundary‐layer investigations. It is shown that the introduction of a characteristic parameter termed by the author the macroviscosity, defined as the product of the friction velocity and the roughness length, enables a single logarithmic profile to be defined for both rough and smooth flow. Finally, the theory of atmospheric diffusion previously advanced by the writer for smooth flow is extended to rough flow in conditions of neutral equilibrium, and shown to be in good agreement with observation.
Observations of rain from non‐freezing clouds
Authors: Smith E. J. , Priestley C. H. B.
Published: February 2007

A description is given of observations made in south‐east Australia of medium and heavy rain falling from clouds which were everywhere warmer than 0°C. Detailed observations were made visually from aircraft and these were supplemented by measurements of the radar echo intensities and drop size spectra within the clouds.

The clouds were all deep cumulus and were over or near the sea. Great concentrations of relatively large water drops were observed in the upper levels of the clouds.
A new method of measurement of cloud‐water content
Authors: Warner J. , Newnham T. D.
Published: February 2007

A new method of measurement of the liquid‐water content of clouds is described. It depends on the change of resistance of a paper tape on being moistened by cloud droplets which impinge directly on it. A continuous and permanent record of the liquid water can be obtained, and variations over distances of a few hundred feet can be detected. Measurements have been made using the technique on a number of cumulus and stratocumulus clouds, some characteristics of which are described.
Photoelectric measurements of the seasonal variations in daylight at Plymouth from 1947 to 1949
Authors: Atkins W. R. G. , Jenkins Pamela G.
Published: February 2007

Daylight received on a horizontal surface has been measured for fourteen years using a Burt vacuum sodium cell and Cambridge thread‐recorder galvanometer. Mean monthly values of daily maxima, in kilolux, are tabulated, also mean monthly values of illumination in kilolux hours. These are compared with similar measurements at Kew in 1947 and 1948, obtained using a selenium cell. The kilolux hours for each month are shown as a percentage of individual years, with mean values for fourteen years and percentage range for variation. Annual totals were 108, 124 and 122 megalux hours for 1947, 1948 and 1949 respectively with 116 as the mean of the whole series. Between these and sunshine or rainfall there is no simple relation. Cloudless days are not the brightest owing to downward reflection from clouds. Darkest days in each month commonly show 17 to 40 per cent as many kilolux hours as do brightest, though smoke pollution may reduce illumination to 5 per cent.
Note on the derivation of the logarithmic velocity profile
Authors: Björgum O.
Published: February 2007

In this note it is shown that under neutral conditions the logarithmic velocity profile is uniquely determined in the fully turbulent region of the lower atmosphere.
Wind stress on water: An hypothesis
Authors: Munk W. H.
Published: February 2007

The form drag of wind on an irregular surface is found to equal the product of U2 (U is anemometer wind‐speed) and a function of the two‐dimensional spectrum of this surface. For a solid surface this function is, of course, independent of U and the form drag is proportional to U2, as observed over land. Over water, Neumann's frequency spectrum and the glitter measurements by Cox and Munk make this function proportional to U, and hence the form drag proportional to U3. The computed form drag is not far out of line with measurements by Van Dorn and others.

The dependence of form drag on the ‘beam‐width’ and frequency spectrum of the surface roughness is discussed. The essential roughness statistic comes close to being the mean‐square slope of the surface, rather than being related to wave height or some other roughness length, as usually assumed. The slope statistics are governed by the high‐frequency part of the wave spectrum, and this feature accounts for the pronounced reduction of form drag by surface ‘slicks,’ and the relatively small effect of a limited fetch. The total drag, c1 U2 + c2 U3 (skin friction + form drag), must be larger at very high winds than if it followed a U2 law, as usually assumed.
On the space and time distribution of showers in a tropical region
Authors: Soane Christine M. , Miles V. G.
Published: February 2007

Charts of daily rainfall in Southern Rhodesia show that the distribution of rain in space and time cannot be associated in any detail with features of the synoptic map.

Displays of precipitation echoes on the screen of a 10‐cm radar situated at Salisbury have been photographed by time‐lapse camera giving great detail and continuity of record.

It is found that echo displays associated with cumuliform cloud can be resolved into a few areas of echo activity which move continuously by a process of new echo formation. These moving areas have been termed ‘progressions’ and progression behaviour is described in terms of individual echo behaviour and in relation to other meteorological observations. The discovery of progressions has introduced order into a type of tropical shower activity which has previously been considered incoherent.
The local wind at Milfield, Northumberland
Authors: Meiklejohn Jane
Published: February 2007

There is a very strong local westerly wind at Milfield, which blows along the foot of the escarpment of the Cheviot Hills. It occurs in any synoptic situation which gives a surface wind between south‐west and west, and the presence of an inversion is not necessary for its appearance. The wind is not purely katabatic, and its main cause appears to be some feature of the local topography.
The brightness distribution of the overcast sky when the ground is snow‐covered
Authors: Petherbridge P.
Published: February 2007

Measurements have been made of the brightness distribution of a densely overcast sky when the ground was covered with snow. The distribution proved to be moze uniform than has been reported for normal ground conditions.

The distribution was found to be somewhat asymmetric, which may have been due to differences in cloud thickness or to the local influence of inter‐reflections between the base of the cloud and the ground below.

The averaged data were found to be represented with reasonable accuracy by the empirical formula: Bθ = 1/2 BZ (1 + cos θ) where Bθ = brightness of the sky at zenith angle θ and BZ = brightness of the sky at the zenith.

The reflection factor of the snow was measured and found to be 80 per cent.
Airflow over an isolated hill
Authors: Scorer R. S.
Published: February 2007

Perturbation theory is used to compute the vertical displacement of a uniform airstream passing over a solitary hill: first for a circular hill, then for a hill of oval section lying across the wind, obliquely to it and along it. The diagrams show contours of the vertical displacement at four different heights above the hill. It is significant that a small but steep‐sided oval hill produces almost as much displacement as a larger circular, less‐steep hill. When inclined obliquely to the airstream the pattern is very asymmetrical, the displacement being greater over the end of the hill that is farther down wind. A hill lying along the wind produces a very small effect.
A note on the parametric representation of non‐circular wind distributions
Authors: Scott J. R.
Published: February 2007

The theory and an example is given of a method of representing a non‐circular wind distribution in which correlation exists between the departures from the means of the computed components. For it to be accurate the distribution of the components must be normal.
A tangent arc of the halo of 24½ °
Authors: Visser S. W. , Alkemade C. T. J.
Published: February 2007

A remarkable halo complex observed in Germany in 1944 is described and theoretically discussed. There appear to be two possible crystal forms. Only one, however, with an inclination of the pyramidal faces of 25° 14′ fulfills the theoretical conditions. As far as we know there is only one other observation of a tangent are of an uncommon halo (in the Netherlands in 1933). It requires an inclination of the pyramidal face of 54° 44′, just the angle measured by Clarke (1822). In both phenomena we are concerned with similar refraction in similar plate‐shaped ice crystals.
A determination of the relation between wind and sea‐surface drift
Authors: Hughes P.
Published: February 2007

The drift of plastic envelopes floating close to the sea surface is related to the gradient wind. The results indicate that in westerly situations a shallow layer near the sea surface moves in approximately the same direction as the gradient wind with about 2 per cent of its velocity.
The climate of Kerman, south Persia
Authors: Beckett P. H. T. , Gordon E. D.
Published: February 2007

The meteorological records and the climate of the Kerman basin are surveyed, with particular reference to wind‐power, probable annual precipitation and calculated transpiration, as factors relevant to the agricultural development of the region.
Some recent airborne measurements of freezing nuclei over Southern England
Authors: Murgatroyd R. J. , Garrod M. P.
Published: February 2007

Daily measurements of freezing‐nucleus concentrations at 10,000 ft over southern England during January 1956 revealed no well‐marked peaks. The results also indicated, however, that the earth's surface was not the main source of freezing nuclei.
Wind profiles and the shearing stress — an anomaly resolved
Authors: Deacon E. L.
Published: February 2007

Reported failures of a generalized wind‐profile equation to predict correctly the shearing stress under certain conditions are found to be associated with low wind speeds close to the surface. The increase of drag coefficient of the surface‐roughness elements (e.g., grass blades) at low Reynolds numbers is the source of these discrepancies.
Long waves, lee waves and gravity waves
Authors: Ball F. K.
Published: February 2007

It is shown that the equation determining the streamlines of large‐scale atmospheric motions (jet streams and long waves) is similar to the equation determining the streamlines of small‐scale gravitational motions of a stratified liquid. Both motions are characterized by the occurrence of jets, the number of jets being determined by the value of a dimensionless parameter. Atmospheric flow at 500 mb is compared with theoretical solutions (derived by Long 1955) of the non‐linear equations for the flow of a stratified liquid. Linearization of the equation for large‐scale atmospheric motions leads to the Rossby wave equation, whereas linearization of the equation for the motion of a stratified liquid leads to Scorer's lee‐wave equation.
The composition of precipitation at Lerwick, Shetland
Authors: Oddie B. C. V.
Published: February 2007

It is shown that most of the salts deposited at Lerwick arrive as sea‐spray rather than in true precipitation. Mg, K and Na are present in very nearly the same proportions as in sea water: but there is a very great deficiency of chlorine, which, it is argued, can only be explained on Cauer's hypothesis that NaCl in aerosol form is dissociated and that Cl or HCl is released.
An experimental system for directly recording statistics of the intensity of atmospheric turbulence
Authors: Jones J. I. P. , Pasquill F.
Published: February 2007

It is demonstrated theoretically that the ‘filtering’ effects exerted on a turbulence record by taking averages over an interval s, for a total sampling time t, may be reproduced by simple electrical filters as far as the variance is concerned. The smoothed rectified output of such a filter may be recorded on a slowly moving chart and, with the further assumption of Gaussian distribution in the amplitudes of the fluctuations, may be read directly as a statistical mean of the standard deviation.

A description is given of an experimental system, and of direct tests of its performance in recording the standard deviation of wind‐direction fluctuations when averaged over 5 sec and sampled over 3 min. Proposed applications are briefly outlined.
Atmospheric extinction of infra‐red radiation
Authors: Deirmendjian D.
Published: February 2007

The effects of scattering on the transmission of 2·6 to 12 micron radiation are analysed as a continuation of an earlier paper. Monochromatic extinction coefficients are determined on the basis of the original haze models and of the exact values of the complex index of refraction for water. The individual extinction cross‐sections are computed with a high degree of accuracy by means of a modified van de Hulst expression.

The results are in good agreement with existing experimental determinations of window transmission except in the 8 to 12 μ region, where they support Roach and Goody's (1958) conclusion on the importance of wing absorption by molecular lines. The computed continuous spectrum of haze extinction presented graphically and in tables, further reveals interesting details which will be useful in determining the relative importance of absorption and scattering in atmospheric infra‐red radiation.

A simple cloud model is also considered, and it is shown that even tenuous clouds may be quite opaque to infra‐red radiation over a wide band. In the window regions, clouds and dense hazes scatter a considerable portion of the incident radiation, thereby contributing to the infra‐red sky background usually attributed to black‐body emission.
Ice‐crystal contact electrification
Authors: Hutchinson W. C. A.
Published: February 2007

An experimental investigation of electrification accompanying the momentary single contact of vapourgrown ice crystals at the same or at different temperatures suggests than any such effect is much smaller than might be expected from Reynolds's report on charging observed with riming spheres and vapour‐grown ice crystals.
The generation of wave energy at a fluid interface by the passage of a vertically moving slender body
Authors: Warren F. W. G.
Published: February 2007

In this paper an estimate is made of the energy absorbed by wave motion at the interface of two superposed fluids when a body passes from one fluid to the other. The fluids are supposed perfect, incompressible, and bounded only by the interface, and axi‐symmetric and symmetrical two‐dimensional cases are considered. The body is supposed to move vertically and approach the interface from a great distance, and after crossing the interface to recede to a great distance, the speed being kept steady throughout. It is assumed that there were no waves originally present at the interface and that no splashing occurs during the crossing. The linear approximation to irrotational waves is used at the interface, and the slender body approximation is used at the boundary of the body. Transform methods are used to solve the Laplace equation for the velocity potential. Expressions are found for the waves set up as the body crosses the interface, and the energy used to generate the waves is found from a calculation of the work done against the wave resistance. The wave energy may be regarded as the sum of the wave energies for two cases : one in which the density difference between the two fluids is small, and another, in which the density of the upper fluid is zero. For the special cases of a spheroid and a spindle‐shaped body, curves are shown of the wave energy against a dimensionless form of the inverse speed. Criteria are given for when maximum wave energy is developed for a thermal, and an estimate of this energy is made. This is done in Section 6.
Calculations of Mie back‐scattering of microwaves from ice spheres
Authors: Herman B. M. , Battan L. J.
Published: February 2007

Thunderstorms containing hail have been found to have extremely large radar reflectivities. Experimental work by Atlas, Harper, Ludlam and Macklin (1960) has shown that hailstones may have unexpectedly large back‐scattering cross‐sections. In order to shed additional light on this problem, the normalized back‐scattering cross‐sections (σb) of spherical ice particles with complex index of refraction N = 1·78 – 0–0024i (N = m – mki where m is the ordinary index of refraction, and mk is the Mie absorption coefficient) were calculated from the complete Mie equations. Small intervals of α (= 2πa/λ where a is the radius of the scattering particle and λ is the wavelength of incident radiation) were taken up to a value of 30. The back‐scattering from large ice spheres is shown to be considerably higher than that from water spheres of the same size. In general, the differences between the reflectivities of ice and water spheres increase with increasing α up to an α of about 60.

Calculations of (σb) were made for various values of the complex index of refraction in order to better understand the properties of the back‐scattering equations.
Rain in East Africa
Authors: Johnson D. H.
Published: February 2007

For mapping daily rainfall over East Africa, a method is used which emphasizes distribution rather than rainfall amount. Isohyets are unsuitable for synoptic studies.

Daily rainfall analyses show large‐scale systems which develop and persist over periods of days. Changes of type continually take place against background seasonal patterns. Day‐to‐day evolutions are frequently untypical of seasonal trends. There is little evidence of mobile features. Patterns do not take the form of zonal bands in preference to other shapes.

Statistics describing the scale, structure and persistence of rain areas are given. Regional differences are discussed.
Study of rainfall over Chittagong Coast during 1955
Authors: Rahmatullah M.
Published: February 2007

The rainfall distribution over Chittagong Coast for the year 1955 was studied to determine the importance of ‘heavy’ rainfall of 3 in. or more in the rainfall distribution curve. Chittagong City and Cox's Bazar were taken as representative stations for this study. In 1955, Chittagong City with an annual normal of 108 in., recorded 148 in. of rain. Cox's Bazar, on the other hand, with an annual normal of 140 in. had only 134 in. of rain. Out of the total of 99 rainy days during 1955, the number of heavy rainfall days in Chittagong was only 14, accounting for 57 per cent of the total rainfall of the year. In the case of Cox's Bazar, out of 108 rainy days during 1955, only 10 days recorded heavy rain of 3 in. or more, accounting for about 35 per cent of the total annual rainfall of the year. It was found that the ‘heavy’ rainfall curve is the most important feature determining the pattern of the rainfall distribution curve over Chittagong Coast.
Some ozone‐weather relationships in the middle latitudes of the Southern Hemisphere
Authors: Kulkarni R. N.
Published: February 2007

The paper discusses relationships observed between ozone and the upper‐air measurements made at Brisbane, Aspendale and Macquarie Island. The correlation coefficients between the short‐term fluctuations of ozone and the temperatures at 100, 200 and 300 mb levels at these places are presented. In general, high ozone was observed to be associated with the sinking of the tropopause, descending of stratospheric air, warming of the lower stratosphere and a southerly flow of air in the lower stratosphere. At Macquarie Island, an instance of the ozone fluctuations in the baroclinic waves of the polar night westerly vortex suggested that the middle stratospheric waves contributed to the unexplained long term variance in total ozone.

The meteorological parameters at the 200 mb level did not reveal the type of oscillation shown by the spring maximum level of ozone with a periodicity of 24 months. From the study of the 60 mb temperatures, it is concluded that the middle stratospheric circulation is playing an important role in deciding the spring level of ozone in middle latitudes of the Southern Hemisphere.
Accuracy of dew and frost points measured by frost‐point hygrometers
Authors: Grant D. R.
Published: February 2007

Apparatus has been built at the Meteorological Research Flight to train observers on the ground in the use of frost‐point hygrometers (Brewer, Cwilong and Dobson 1948). Using this equipment the frost point of the air being measured is known accurately, and from readings by a number of observers over the complete range of the instrument an estimate of the root‐mean‐square error of measurement can be made. This error can be broken down into a systematic error and random error, both of which vary with the humidity being measured. The systematic and random errors of the individual observers can also be established.

The results show that the r.m.s. error of a dew‐point measurement is about 0·7$C. The r.m.s. error of a frost‐point measurement is 1·0$C at — 40$C increasing to 1·7$C at — 75$C. If the systematic error were eliminated the standard deviation of the random errors would be about 0·6$C for dew points, 0·8$C for frost points of — 40$C and 1·6$C for frost points of — 75$C. The details of the results are given in Tables 1 and 2.
Precipitation from layer cloud
Authors: Stewart J. B.
Published: February 2007

Eight years of data on layer clouds obtained on aircraft ascents were related to ground observations of precipitation reported by the nearest full synoptic station, and used to investigate the variation in the occurrence of precipitation at the ground with the height of cloud base above the 0°C level and the variation in intensity of precipitation with cloud thickness.

It was found that if the base of the layer cloud was more than 1 km above 0°C level there was less than a five per cent chance of precipitation reaching the ground ‐ however thick the cloud was ‐ compared to a nearly 90 per cent chance of precipitation for clouds with bases less than a kilometre above the 0°C level and more than 2 km thick. For layer clouds with their bases below the 0°C level, it was found that 0·4 km was the minimum thickness to give any precipitation and 1 km and 3 km were the respective minimum thicknesses for continuous slight and continuous moderate rain to be produced. A similar analysis was carried out for layers up to 2 km thick wholly below the 0°C level with comparable results. It was also found that at least 60 per cent of precipitating layer clouds of thickness less than 2 km with bases below the 0°C level and unaffected by layers above, gave precipitation by the coalescence process alone.
A mid‐latitude biennial oscillation in the variance of the surface‐pressure distribution
Authors: Shapiro R.
Published: February 2007

Some evidence is presented which indicates the existence of a weak biennial oscillation in the spatial variance of the surface‐pressure distribution in mid‐latitudes.
Determination of ozone amounts by the dobson spectrophotometer using the focused sun method
Authors: Hamilton R. A.
Published: February 2007

When the effective path length μ is greater than 4 the focused sun method must be used when measuring the amount of atmospheric ozone by the Dobson spectrophotometer. Errors are introduced by light from the sky, and by light scattered within the spectrophotometer. A method of evaluating these errors is described, and corrections are tabulated which enable measurements of ozone amount to be made when μ is in the range 4 to 8·5.
The interpretation of stellar shadow‐bands as a consequence of turbulent mixing
Authors: Townsend A. A.
Published: February 2007

Recently published measurements of shadow‐band patterns produced by star‐light at ground level are analysed using the theory of wave‐propagation in a turbulent medium. The measured spatial and time spectra of the patterns can be described quantitatively by assuming that the optical inhomogeneities are produced by turbulent mixing in the earth's boundary‐layer and in shallow layers at heights around 8 km. Characteristics of the assumed turbulence in the upper air are estimated to be: mean height 8 km, layer depth 90–200 m, r.m.s. velocity fluctuation in wind direction 1·5‐2·0 m sec−1, r.m.s. temperature fluctuation 0·2°C.
Some aspects of the large‐scale turbulence and diffusion in the atmosphere
Authors: Kao S.‐K.
Published: February 2007

The Eulerian and Lagrangian autocorrelations and energy spectra of the large‐scale turbulent motion in the atmosphere are computed and analysed. It is found that the distributions of the Eulerian and Lagrangian autocorrelations of the zonal velocities show the characteristic of an exponentially decreasing function, whereas those of the meridional velocities exhibit the behaviour of a sinusoidal function with a damping amplitude. The energy spectra appear to be proportional to the minus second power of the frequency in the high frequencies.

Analyses are also made of the energy spectra, autocorrelations, and the Eulerian‐Lagrangian time scale transformation in a planetary wave model. The ratio of the Eulerian and Lagrangian frequencies for the large‐scale atmospheric turbulence is found to be a function of the mean zonal velocity, latitude, and the angular wave number of the planetary wave. Comparisons are made of the energy spectra and autocorrelations derived from the planetary wave model and those found from observations.
Observations of hydrometeor charge evolution in thunderstorms
Authors: Maccready P. B. , Proudfit A.
Published: February 2007

Systematic observations were made of hydrometeor charges associated with thunderstorms at Flagstaff, Arizona. The measurements were made from a light aircraft by the standard induced‐charge method, in and below clouds which were entirely supercooled. The aircraft would spiral within the central upcurrent up into the cloud and later spiral down through the precipitation shafts. From these limited cases, a rather consistent picture emerged: (a) generally, charges on graupel and hail within the supercooled clouds were positive (measurements made as high as the −17.5°C level), (b) below the cloud at the + 2° to + 8°C level, just where the melting of the hydrometeors was apparently complete, the hydrometeors became abruptly negative, (c) at still lower, warmer levels the charge magnitudes were consistently smaller, with both signs represented but predominantly negative. The data suggest that a strong hydrometeor charging mechanism is associated with the melting of ice hydrometeors outside the cloud. The maximum charge magnitudes appeared comparable to the amounts which would be limited by breakdown gradients at the hydrometeor surface.
Changes in amounts of sunshine in British Columbia, 1901‐1960
Authors: Powell J. M.
Published: February 2007

5‐year running means and 20‐year averages of annual and seasonal sunshine hours for 11 stations in British Columbia having a record of at least 30 years are discussed. In comparison with the period 1921‐40 sunshine hours have been less in all seasons at most stations for the periods 1901‐20 and 1941‐60. Coastal stations had the greatest change during the summer, but inland stations had the greatest change during the winter. All stations recorded the least change in the spring.
A note on high velocity modes of the atmosphere
Authors: Arora M. K.
Published: February 2007

Theoretically there can exist modes of the atmosphere for which the phase velocity is indefinitely large. However, the physical condition of the atmosphere prohibits their occurrence.
Observations of the modification of the microclimate at a leading edge
Authors: Dyer A. J. , Crawford T. V.
Published: February 2007

Temperature profiles observed over a heavily irrigated grass field in the midst of dry surroundings show continuous modification up to the maximum height of measurement (5 m) even at a distance of 200 m from the leading edge.

Considerable variation of eddy fluxes in the vertical is demonstrated. The surface fluxes are found to undergo gradual adjustment.

These observations illustrate that a site of considerable extent is required for micrometeorological and agricultural studies before horizontal uniformity can be assumed.
The divergence of horizontal eddy flux of momentum in the lower equatorial stratosphere
Authors: Tucker G. B.
Published: February 2007

Evidence is presented to support the assumption that the divergence of horizontal flux of momentum due to large‐scale eddies has a sinusoidal variation of the same period as, but with a phase difference from, the zonal wind oscillation of approximately 26 months. The phase difference appears to be about μ/2 with the divergence wave preceding the zonal wind wave. The evidence is not regarded as conclusive.
A long‐period recorder for wind speed and direction
Authors: Sumner C. J.
Published: February 2007

A description is given of a run of wind and direction‐sensing mechanism for use in conjunction with a battery operated long‐period recorder (Sumner 1959), which records the variables ten times per hour. It is a relatively cheap semi‐portable instrument and is intended for use in remote areas, or as an investigational tool which may be readily moved to new sites.
The limitations of analogues selected from sequences of daily weather types over the British Isles
Authors: Lewis R. P. Waldo , Murray R.
Published: February 2007

An account is given of a numerical experiment in extended period forecasting using analogues selected on the basis of similarity of sequences of daily weather types. The resulting forecasts of weather sequences are significantly better than chance for between 5 and 10 days. This result is probably largely due to persistence.
The photochemical formation of electronically excited oxygen molecules in the atmosphere
Authors: Wayne R. P.
Published: February 2007

Spectroscopic studies of the airglow indicate that electronically excited molecular oxygen in the 1Δg and 1Σg+ states is produced in the atmosphere. The way in which the excited states are formed in the atmosphere has been the subject of much speculation, and the present paper attempts to evaluate some of the mechanisms proposed in the light of laboratory experiments.

The most probable excitation mechanism for O2 (1Δg) appears to be the primary step in the photolysis of atmospheric ozone:

O3 + hν (λ < 3,100 Å) → O2 (1Δg) + (1D).

O2 (1Δg+) may then be formed in the energy‐pooling process:

O2 (1Δg) + O2 (1Δg) → O2 (1Σg+) + O2 (1Σg−).
Analysis of low‐level, constant volume balloon (tetroon) flights over New York City
Authors: Hass W. A. , Hoecker W. H. , Pack D. H. , Angell J. K.
Published: February 2007

Constant volume balloon (tetroon) flights made over New York City at heights of about 300 metres during June of 1965 are analysed. The transponder‐equipped tetroons were tracked to distances exceeding 100 km by means of the wsr‐57 weather radar located in Central Manhattan. On non‐sea breeze days the tetroons tend to move towards low pressure with an angle of 35 degrees, and to move with about two‐thirds of the geostrophic wind speed. There is a correlation of 0.73 between lapse rate and tetroon‐derived r.m.s. vertical velocity, and of 0.43 between lapse rate and Lagrangian period of vertical oscillation. Tetroon‐derived vertical velocities are also used to obtain estimates of the mean Reynolds stress (1.3 dynes cm−2 at flight level) and the downwind variation of vertical diffusion over an urban area.
Variations in the content and flux of water‐vapour over north‐eastern North America during two winter seasons
Authors: Barry R. G.
Published: February 2007

Atmospheric water‐vapour content and horizontal flux of water‐vapour are evaluated for twenty stations for November‐February 1956‐;7 and 1957–8. Mean patterns of vapour content and the total and eddy transport between the surface and 500 mb are analysed to show the marked differences between the two seasons. More detailed information is provided by average values of vapour and flux for a number of types of airflow pattern over Labrador‐Ungava.
Diffusion in the atmospheric surface layer: comparison of similarity theory with observations
Authors: Klug W.
Published: February 2007

The results of similarity theory applied to turbulent diffusion in the atmospheric surface layer are compared with concentration measurements as obtained from Project ‘Prairie Grass.’ The comparison shows that good agreement between theory and observation can be obtained only when the ‘lateral turbulence level’ is included through a regression equation.
An objective method for estimating wind‐speed fields from wind‐direction fields
Authors: Mancuso R. L.
Published: February 2007

An objective method is described for obtaining an estimate of the wind‐speed values within the interior of a region when only the streamline field for the region and the wind‐speed values along the boundary are given. The method has been developed and tested for possible use in data‐scarce areas where conventional wind analyses can not be made, but where wind‐direction fields might be derived with reasonable accuracy and detail from satellite cloud photographs. The basic approach consists of computing the wind speeds within the interior of the region by stepping downwind along the streamlines from the known wind‐speed values at the inflow boundary. Divergence is assumed to be constant along each streamline and is determined in a manner such that successive computational cycles minimize the differences between the computed and known wind speeds at the outflow boundary. The testing was conducted using known wind‐velocity fields over the United States and also ATS‐3 cloud‐motion data over the Caribbean. The computed wind‐speed fields were found to be in reasonably good agreement with the actual wind‐speed fields.
An observational study of the energy balance of the stationary disturbances in the atmosphere
Authors: Holopainen E. O.
Published: February 2007

Different terms in the equations describing the balance of kinetic energy and available potential energy in the so‐called stationary disturbances or standing waves (deviation of the atmosphere's time‐mean flow from axial symmetry) are evaluated approximately by using the observational statistics of the atmospheric flow. Because many simplifications and assumptions have been necessary in order to get estimates of certain terms, the results only give a rough first‐estimate picture about the maintenance of the stationary disturbances.

The results indicate that in winter the stationary disturbances are typically baroclinic waves, which get available potential energy from the temperature distribution of the zonally‐averaged mean flow and partly convert it into kinetic energy to offset the destructive effect on the latter by small‐scale turbulent friction, large‐scale transient motions and conversion into zonally‐averaged mean motion. The most important ‘ external ’ forcing seems, from the energy point of view, to be the stationary heat sources and sinks, which in winter destroy the available potential energy of the stationary disturbances; the effect of mountains in the energy balance of the standing waves seems to be relatively minute and actually smaller than the kinematic and thermal effects of large‐scale transient flow systems.

In summer the stationary disturbances appear to form a thermally‐driven system, where the frictional loss of kinetic energy is compensated for by a conversion from the available potential energy, which in turn is maintained by generation due to diabatic heating.
The effect of revised collision efficiencies on the growth of cloud droplets by coalescence
Authors: Bartlett J. T.
Published: February 2007

The collection efficiencies of water drops falling in still air have been recalculated by Hocking and Jonas (1970). In this paper these revised values have been used to estimate the rate of production of large droplets (r > 30 μm) by coalescence. It is found that there is an increase in the rate of production of droplets with radii of about 20 to 25 μm compared with the rate calculated using Hocking's earlier (1959) values, but generally a decrease in the rate of production of droplets with radii 20 to 25 μm. It is also shown that neglecting the small, but finite, collection efficiencies predicted for droplets with radii less than about 15 μm has negligible effect on the rate of production of larger droplets.
A note on the dependence of atmospheric predictability on baroclinic development
Authors: Everson P. J. , Davies D. R.
Published: February 2007

A two‐level, quasi‐geostrophic model, described by Everson and Davies (1970), is used to study the dependence of duration of predictability (as defined by, e.g., Charney et al. 1966) on the phase, at some initial time in the integration, of global scale baroclinic development (expressed in the model in terms of fluctuations in eddy kinetic energy, K').

Using firstly an invariable subgrid scale coefficient in a control run of 120 days, sinusoidal perturbations, wave length approximately 6,000 km, of the geopotential heights are inserted at all the grid points at (a) day 72, corresponding to a maximum in model K', and (b) day 84, corresponding to a minimum in model K'. The consequent ‘perturbed’ integrations are compared to the control values by taking the r.m.s. of the difference in the 500 mb calculated temperature distributions, and determining the time taken for this to increase to the ‘persistence’ value, i.e. the maximum r.m.s. difference between two randomly selected model states. The doubling time of error in (a) was seen to be 12 days leading to a model predictability of 24 days, and in (b) it was seen to be 17 days, leading to a predictability of 34 days: these values are related to an initial perturbation amplitude of 1°C.

These experiments were then repeated using a variable subgrid scale coefficient, depending on grid scale horizontal temperature gradient as described by Everson and Davies (1970). The results were; (a) working from a day of maximum K', the doubling time of error was reduced to 8 days, approaching the value obtained by primitive equation numerical models and corresponding to a predictability of 16 days; (b) working from a day of minimum K', the doubling time of error was 13 days, corresponding to a predictability of 26 days. The results in both cases show that predictability, as calculated from some initial phase of baroclinic development, is 50 per cent higher as measured from a maximum in K'compared with a minimum in K'. It also drops sharply with increase in the degree of model sophistication (expressed in the system discussed in this paper as variability of the subgrid scale coefficient).