bluuebunny/crossref_metadata_2025 huggingface dataset:
Early Jurassic allotherians from South Wales (United Kingdom)
Authors: Clemens W. A.
Published: February 2007

Abstract. Fossils from two fissure fillings in Pant Quarry (designated Pant 4 and Pant 5), South Wales, United Kingdom, probably of Early Jurassic age document a taxonomically diverse vertebrate fauna, the Morganucodon-sphenodont fauna, composed of several kinds of reptiles, non-mammalian synapsids, and mammals. Six isolated molariform teeth from Pant 4 and 5 fissures clearly record the presence of Thomasia (Mammalia, Allotheria, Haramiyidae), a genus previously known only from purported Late Triassic faunas of southwestern England, France, Belgium, Luxemburg, Germany, and Switzerland. Small morphological differences from teeth in the larger English and continental European samples warrant identification of the Welsh material as Thomasia cf. moorei. The highly derived morphology of an isolated molariform tooth from Pant 5 fissure indicates the presence of another, possibly allotherian, taxon. Fossilien aus zwei wahrscheinlich unterjurassischen Spaltenfüllungen (Pant 4 und Pant 5) im Steinbruch Pant in Süd-Wales dokumentieren eine taxonomisch diverse Wirbeltierfauna. Diese Morganucodon-Sphenodontiden-Fauna besteht aus verschiedenen Formen von Reptilien, Synapsiden und Säugetieren. Sechs isolierte molariforme Zähne aus den Spaltenfüllungen Pant 4 und Pant 5 belegen eindeutig das Vorkommen von Thomasia (Mammalia, Allotheria, Haramiyidae), einer bisher nur aus vermutlich obertriassischen Faunen Südwest-Englands, Frankreichs, Belgiens, Luxemburgs, Deutschlands und der Schweiz bekannten Gattung. Geringe morphologische Unterschiede zu dem umfangreicheren Material aus England und Kontinental-Europa sprechen für die Identifikation des neuen Materials als Thomasia cf. moorei. Die stark abgeleitete Morphologie eines isolierten molariformen Zahnes aus der Spalte Pant 5 belegt das Vorkommen eines anderen Taxons, das möglicherweise auch den Allotheria zuzuordnen ist. doi:10.1002/mmng.200600018
Quantification of nepetalactones in catnip (Nepeta cataria L.) by HPLC coupled with ultraviolet and mass spectrometric detection
Authors: Wang Mingfu , Cheng Ka‐Wing , Wu Qingli , Simon James E.
Published: February 2007

Nepetalactones, the major chemical components of catnip (Nepeta cataria L.), were analysed by reversed‐phase HPLC coupled with UV and MS detection. Two major nepetalactones, Z,E‐nepetalactone and E,Z‐nepetalactone, were successfully identified and quantified. The linearity range for Z,E‐nepetalactone was determined as 0.00655–0.655 mg/mL with a correlation coefficient of 0.9999, and the linearity range of E,Z‐nepetalactone was found to be 0.00228–0.456 mg/mL with a correlation coefficient of 0.9999, under UV detection at 228 nm. The linearity ranges were from 0.00164 to 0.0328 mg/mL, with a correlation coefficient of 0.9999, for Z,E‐nepetalactone and 0.00114–0.0228 mg/mL, with a correlation coefficient of 0.9999, for E,Z‐nepetalactone by MS detection with selected ion monitoring of ion peak m/z 167. The MS detection was found to be more sensitive than UV detection and this method was validated as simple, reliable and sensitive for catnip nepetalactone analysis. This method can be used for identification and fingerprinting of catnip products. Copyright © 2007 John Wiley & Sons, Ltd.
Identification of kinetic models for the assessment of reaction hazards
Authors: Kossoy A. , Akhmetshin Yu
Published: February 2007

The assessment, control, and mitigation of reaction hazards is primarily based on the use of kinetic models. These kinetic models are used for the assessment of reaction hazards, the operation and control of the reactor, the design of emergency relief systems, estimation of the consequences of a reaction runaway, etc. The validity of these assessments depends highly on the validity of the kinetic model employed.

Several steps are required to identify a suitable kinetic model. This includes:

Selection of the model type.

Estimation of the model's parameters using available data.

Validation of the model.

This article discusses each of these steps in detail and identifies problems associated with each step. Several practical examples are used to demonstrate these problems.

The results show that (1) the results are sensitive to a number of assumptions, (2) mistakes may originate from misinterpretation of the thermal data, and (3) computational methods do exist to provide suitable kinetic models for hazard assessment.

The analysis employed assumes a batch‐reaction system, since most of the kinetic data available is derived from batch calorimetric equipment. © 2007 American Institute of Chemical Engineers Process Saf Prog, 2007
On Wilson's theory of the collection of charge by falling drops
Authors: Whipple F. J. W. , Chalmers J. A.
Published: February 2007

Wilson's theory of the acquisition of charges by drops falling through a region containing ions is worked out in detail; diagrams of the paths of ions and curves of the rates of acquisition of charge are drawn. The applications of the theory to the building up of fields in clouds and to the charging of raindrops are briefly discussed.
Mean upper contour patterns of the northern hemisphere — the thermal‐synoptic view‐point
Authors: Sutcliffe R. C.
Published: February 2007

The mean 500 mb contour patterns and 1,000‐500 mb thickness patterns for the northern hemisphere in January and July are examined. The orographic‐dynamical hypothesis advocated by Bolin (1950) is considered. A thermal‐synoptic explanation, resting mainly on the direct thermal effects of land and sea modified by baroclinic synoptic processes, is regarded as satisfactory.
Bubble theory of penetrative convection
Authors: Scorer R. S. , Ludlam F. H.
Published: February 2007

The process of convection is described in terms of a unit or proton of convection ‐ the bubble. A rising bubble of warm air sheds its outer skin steadily into a disturbed wake until it becomes exhausted completely or spreads out at a stable layer. The wake is a region where the ascent of further bubbles is favoured. The wakes of small bubbles close to the ground are aggregated into larger bubbles, which are more dilute, up to a level where they begin to penetrate hitherto undisturbed air, and then they waste away as they ascend further.

The air above a bubble is lifted (and cooled) as the bubble approaches and then drains down the outside, the air close to the bubble being mixed into the wake. The wake of a clear bubble is buoyant but that of a cloudy bubble may sink if it is sufficiently chilled by dilution with surrounding clear air.

The drag on a bubble is estimated from observations on rising cumulus towers, and a linear relation between buoyancy and limiting velocity is proposed. From this the horizontal velocity of the bubble relative to the surrounding air is deduced to be about the same as the vertical velocity when it ascends through strong shear.

A bubble is a compact stable configuration for a rising element. Near the ground the heat is transported by small bubbles, which are less efficient, and therefore require a greater lapse rate, than the larger ones which can operate higher up. The process of aggregation is again renewed within large clouds so that the bubbles found at the top may be more dilute than if they had ascended directly from the base. Clouds growing in a shearing current will grow into the shear.
The growth of ice crystals in a supercooled water cloud
Authors: Mason B. J.
Published: February 2007

Equations are derived for the growth rate of ice crystals in the form of thin plates and prismatic columns suspended in a supercooled water cloud of given temperature. The effect of the fall motion of the crystal on its development is discussed ‐ in particular a criterion is derived for the transition from polyhedral to dendritic growth. Ice crystals grown in supercooled water clouds produced in large cold chambers reveal a double change of habit in the temperature range 0°C to −40°C. Experimental determinations of the growth rates of plate crystals growing at −2.5°C and prisms at −5°C are in fairly good agreement with the theory.
Radar echoes at vertical incidence from a horizontally stratified atmosphere
Authors: Browne I. C.
Published: February 2007

An exceptional radar echo of long duration which was observed from the zenith of an apparently clear sky is described, and it is shown that the height of origin of the echo was close to that of an anticylonic ‘inversion’ which was present at the time. It is deduced that the echo cannot have been due to a layer of water or dust haze at the inversion, but that it must have been caused by an abrupt discontinuity in the lapse rates of temperature, humidity, or both. If changes in humidity alone are taken into account, then in order to explain the observed intensity of the echo, it is necessary to suppose that the dew point changed by 15°F through a layer not more than 300 ft deep. It is suggested that more use might be made of radar for investigating such tropospheric discontinuities.
A quantitative analysis of the evolution of large‐scale flow with regard to the effect of eddy motion
Authors: Berson F. A.
Published: February 2007

The theory of pressure change by barotropic redistribution of absolute vorticity is extended to include the effect of an eddy motion represented by the departure of the daily value from a running five‐day mean. Application is made to a case in which the mean motion at the 500 mb level is featured by quasi‐stationary approximately zonal flow over North America and by slowly moving large vortices farther downstream (blocking situation of June‐July 1949). One result indicates the potentiality of a technique of forecasting the evolution of mean flow based on a persistence tendency of the ‘errors’ in barotropic tendency computations on mean charts. A further result concerns the interpretation of the ‘error’ field in the light of the neglected processes. There is, contrary to earlier results, no evidence of standing perturbations due to mountain ranges, but the horizontal eddy transfer of vorticity is shown to be an important factor. It is demonstrated that the latter transfer, viz., by the smaller eddies on approximately the cyclone‐wave scale, is mainly directed against the gradient of vorticity in the mean flow, thereby playing an essential role in the maintenance of the larger eddies. The transfer coefficient (diffusivity of relative geostrophic vorticity) is therefore predominantly negative, and its magnitude is from 109 cm2 sec−1 to 1010 cm2 sec−1. The action of the individual smaller eddies in transferring mean vorticity is evidenced by their paths in the relevant mean flow patterns.
Organization of kinetic energy realized in the atmosphere
Authors: McIntyre D. P.
Published: February 2007

The methods of Margules and Normand for investigation of the problem of storage and transformation of energy in the atmosphere are briefly described. Through discussion of an example of Margules it is shown that consideration must be given to the manner in which the kinetic energy, created in the process of energy transformation, is organized. In particular it is shown that dynamic factors severely limit the quantity of thermodynamic energy which can be released in the atmosphere.
A method for recording the formation and persistence of water deposits on plant shoots
Authors: Hirst J. M.
Published: February 2007

Apparatus has been designed to record the amount of water deposited on plant shoots by rain, dew and guttation, and how long the surfaces remain wet. These factors greatly influence the extent to which plants are infected by fungi causing such diseases as potato blight.

The water on a cut potato shoot, sealed into a water‐filled chamber placed on a balance, can be weighed by recording, on a rotating drum, the changes in equilibrium of the beam. Deposits from rain appear rapidly; their persistence depends on the weather. In contrast, dew is deposited slowly over a long period and dries more rapidly. The heaviest dew deposit recorded was 6.9 × 10−3 g cm−2 compared with 9.6 × 10 g cm−2 for the amount of water retained during rain.
Secular changes in the rainfall regime of SE. Australia
Authors: Kraus E. B.
Published: February 2007

Analysis of long‐series rainfall records from Victoria and New South Wales shows a decrease of summer rainfall to a minimum about the turn of the century, and fifty years' gradual increase since then. Winter rainfall trends were opposite. Fluctuations of a much larger amplitude affected the rainfall regime of autumn and spring, suggesting possibly a discontinuous change of the climatic development about 1893.

The winter rainfall of southern New South Wales is positively correlated with the mean strength of the westerlies at 300 mb. The correlation is negative in summer. It is concluded that the changes of the rainfall regime were associated with an increase of intensity of the upper westerlies to a maximum at about 1900 and a following decrease. During the period of maximum mean westerly flow the formation of east‐coast cyclones in autumn and spring may have been inhibited and the monsoon rains of tropical Queensland were below normal.
The coalescence between small water drops
Authors: Telford J. W. , Thorndike N. S. , Bowen E. G.
Published: February 2007

An experiment is described for measurement of the rate of coalescence in a cloud of droplets of nearly equal size. It is found that the value of the collection efficiency is unexpectedly high, and a physical explanation of the effect is given. The influence of electric charges on the droplets has been observed, and it is shown that increases by a factor of up to 20 in the collection efficiency are possible.
Some observations of turbulence near the sea bed in a tidal current
Authors: Bowden K. F.
Published: February 2007

Oceanographers are interested in turbulence in the flow of water in the sea or in estuaries because of its influence on the dynamics of water movements and mixing. These processes are more usually studied by their large‐scale effects, and detailed investigation of the turbulent fluctuations has been attempted less frequently in oceanography than on the model scale or in the atmosphere. This paper deals with fluctuations in the velocity components. Earlier observations were reviewed by Bowden and Proudman (1949), who also described experiments in the Mersey estuary, using the Doodson current meter. Further observations on similar lines were described by Bowden and Fairbairn (1952a). An attempt to measure the vertical fluctuations as well as the horizontal fluctuations was made by Francis, Stommel, Farmer and Parson (1953) in the Kennebec estuary, Maine.

The observations described in this paper were made using an electromagnetic flow meter, a new type of instrument for this purpose. It was possible to measure the vertical component w, as well as the longitudinal component u, of the fluctuations, and hence the correlation between them. The instrument was designed at the National Institute of Oceanography, and uses alternating current at 50 c/s, passed through a coil, to produce the magnetic field. Two pairs of electrodes are used to measure the two components of flow in the plane perpendicular to the direction of the magnetic field. The measuring unit is only 4 in. in diameter and two such units can be mounted in various positions on a tripod, 6 ft high, which is laid on the sea bed. The potential difference across the electrodes is approximately 50 μv per kt, and is amplified by electronic circuits after induced p.d.'s, other than those due to the flow of water, have been balanced out. The output is recorded photographically.

The observations at sea were made off Red Wharf Bay, Anglesey, in an area from 12 m to 20 m deep, where measurements of tidal currents and bottom friction had been made previously (Bowden and Fairbairn 1952b). The tidal currents at springs reach a velocity of about 2 kt at the surface. The technique employed was to lower the tripod from an anchored boat, a canvas fin keeping it orientated in the direction of the mean current while being lowered. The tripod with the measuring units remained stationary on the bottom while the records were taken and was raised again before the tidal current changed direction.
An experimental investigation of the 9.6 μ band of ozone in the solar spectrum
Authors: Walshaw C. D. , Goody R. M.
Published: February 2007

Mean heights of atmospheric ozone derived from two years' observations of the 9.6 p vibration‐rotation band are discussed. In each year there is a seasonal trend with a minimum mean height in summer and an annual range of 3.4 km. Careful consideration of sources of systematic errors shows that this result is probably due to changes in the ozone distribution, and a plausible seasonal cycle of changes of the ozone concentration in the troposphere and lower stratosphere is discussed. No other significant result is obtained and there is very little residual variance available for correlation with other meteorological phenomena.
The air flow over a ridge — the effects of the upper boundary and high‐level conditions
Authors: Corby G. A. , Sawyer J. S.
Published: February 2007

The solution obtained by perturbation theory for the airflow over a ridge depends on the mathematical conditions imposed at the upper boundary of the region for which a solution is obtained. New arguments are developed as to the choice of upper‐boundary condition appropriate to the atmospheric problem; these lead to the solution already adopted by Queney (1947).

In certain airstreams it is possible for lee waves to have their largest amplitude in the upper troposphere and stratosphere. The character of the airstream at high levels plays a dominant part in determining the characteristics of these waves, but it has only negligible effects on the more familiar type of lee wave which has its largest amplitude in the lower troposphere.
Study of the SO2 oxidation in solution and its role in atmospheric chemistry
Authors: Junge Chr. E. , Ryan T. G.
Published: February 2007

The mechanism of SO2 oxidation in diluted catalytic solutions was studied. It was found that the oxidation stops after a certain pH value is reached. In the same catalytic solutions, the maximum possible SO4− formation is a linear function of the SO2 partial pressure in the air.

This mechanism of SO4− formation can account for observed SO4− concentrations in rain, fog, and smog only if some neutralizing cations in the aerosols or traces of NH3 in the air are present. It is shown that in the latter case the system SO2NH3‐catalytic solution can explain the main features of SO4− formation in our atmosphere.
Radar echoes from atmospheric inhomogeneities
Authors: Jones R. F.
Published: February 2007

The possibility that radar echoes from atmospheric inhomogeneities are the explanation of echoes received in conditions which make it certain they are not received from precipitation elements (‘angel’ echoes) is examined quantitatively. It is shown that such an explanation is theoretically possible but that the required refractive index changes are large, involving changes of a few mb in vapour pressure and/or a few degrees C in temperature in a distance of about 25 cm. Reflection of the main or side‐lobe energy at a limited quasi‐horizontal surface is shown to give the most likely meteorological explanation, but the inability to measure changes of refractive index in the free atmosphere to the required accuracy prevents positive confirmation.
The reflection of short‐wave radiation by vegetation
Authors: Monteith J. L.
Published: February 2007

The fraction of short‐wave radiation reflected from agricultural crops was measured from May till September 1958 using two portable solarimetric thermopiles. Maximum reflection coefficients for grass, lucerne, potatoes, sugar beet, and spring wheat were between 0·25 and 0·27. Lower values found in the early stages of crop development, and for spring wheat even at maturity, can be correlated with low leaf areas and mutual shading of the leaves, also reduced reflection. Data by Billings and Morris (1951) have been used to compute total reflection coefficients for different types of vegetation including two desert species and to explain why these do not normally differ as much as the coefficients for the visible component.
Mean meridional distributions of ozone in different seasons calculated from umkehr observations and probable vertical transport mechanisms
Authors: Ramanathan K. R. , Kulkarni R. N.
Published: February 2007

The paper contains a study of the mean meridional distributions of ozone in different seasons. The vertical distributions of ozone at a number of stations at different latitudes in the Northern Hemisphere were worked out from the intensities of light scattered from the zenith sky on individual clear days using method B, i.e., the method of curve fitting, with suitable correction for secondary scattering. Diagrams of vertical distribution corresponding (1) to high ozone amounts (frequent in winter and spring) and (2) to low ozone amounts (frequent in summer and autumn) are shown. Mean distribution diagrams are also given for the months of March, July and November. An important feature of the distribution is the strong increase in ozone amount in March below 18 km when the latitude increases beyond 30°. The results are discussed in relation to the idea of a poleward flow of air from the lower stratosphere and the neighbourhood of the equatorial tropopause, as suggested by Dobson and Brewer from frost‐point measurements over the United Kingdom. The existence of a stratospheric warm air pool over the middle latitude in winter and spring as revealed by sounding‐balloon ascents is confirmatory evidence of this. The influence of the pool of cold air which exists in winter above 20 km in the stratosphere of the dark polar night is also considered. It is suggested that in winter and spring there is an ozone‐regenerating cycle due to meridional circulation in the stratosphere of tropical and middle latitudes, which carries air from the lower equatorial stratosphere to lower levels in the stratosphere of middle latitudes and puts back some of this accumulated air to higher levels in the equatorial stratosphere above 25 km. The more vigorous this circulation, the greater will be the rate of ozone storage in the lower stratosphere of extra‐tropical latitudes.
The fragmentation and electrification of freezing water drops
Authors: Mason B. J. , Maybank J.
Published: February 2007

The freezing of water drops is often accompanied by shattering of the ice shell and the production of small ice splinters. These phenomena have been studied in relation to the drop diameter in the range 30 μ to 1 mm, the nucleation temperature of the drop, the air content and purity of the water. The number of splinters produced is largely governed by the nucleation temperature (the degree of supercooling) which controls the quantity of air released during freezing and is not very dependent on drop size. Slightly supercooled drops of 1/10−1 mm diameter produced, on average, 20 to 50 splinters. The mechanism of drop fragmentation is discussed and the potential importance of splintering in the ice‐nucleus economy of clouds is assessed.

Fragmentation of freezing drops is accompanied by electrical charging, usually with the splinters positively charged and the drop residue carrying a negative charge. The magnitude of the residual charge which, on average, is observed to be about 10−3 e.s.u. for a millimetre drop, is related to the same factors which control splinter production. Charging by this mechanism would not appear to be of major importance in the electrification of thunderstorms.
Winds in the upper atmosphere
Authors: Greenhow J. S. , Neufeld E. L.
Published: February 2007

A systematic study of the winds in the upper atmosphere has been carried out during the 5‐yr period 1953 to 1958. At heights of 85 to 100 km regular prevailing and periodic tidal wind components have been resolved. Components of the prevailing wind of about 20 m sec–1 towards east are observed during the summer and winter months, with similar westward components during spring and weak westward winds in autumn. Large southward components of approximately 20 m sec–1 are observed during the summer. The amplitude of the semi‐diurnal periodic wind is also about 20 m sec–1, and this component can usually be represented by a vector which rotates in a clockwise direction with constant amplitude twice every 24 hours. Large departures from this simple model occur at certain times of the year. Measurements of the 24‐hr and 8‐hr periodic wind systems are also described, and an upper limit of 2 m sec–1 is determined for the lunar semi‐diurnal wind component.
Cloud‐droplet growth by condensation in cumulus
Authors: Mason B. J. , Chien C. W.
Published: February 2007

The growth of droplets by condensation upon a spectrum of salt nuclei is followed as they are carried up in a small cumulus which mixes and exchanges heat, momentum and water vapour with its surroundings. The vertical velocity, water content, supersaturation and cumulative drop‐size distributions are plotted as functions of time and height above cloud base. Growing cloud droplets are continually being transferred from the cloud to the drier environment and replaced by new condensation nuclei. The fact that some droplets remain in the cloud longer than others is largely responsible for the evolution of a broad drop‐size distribution which much more closely resembles observed spectra than those obtained from previous calculations for a closed parcel. Regarding the formation of large droplets, the calculations show that droplets exceeding 20 μ in radius arise on salt nuclei of mass 10−10 g and droplets larger than 30 μ radius arise on nuclei of 10−9 g within ten minutes of the air passing through the condensation level. Continued growth in a succeeding thermal and further deformation of the droplet spectrum by coalescence will produce even larger drops, but nevertheless it is difficult to explain the appearance of droplets larger than 30 μ in concentrations of order 1 cm−3 in terms of their growth on reported concentrations of giant hygroscopic nuclei.
Infra‐red absorption, scattering, and total attenuation cross‐sections for water spheres
Authors: Herman B. M.
Published: February 2007

Calculations of the normalized absorption, scattering, and total attenuation cross‐sections of water spheres are presented for the wavelength range from 4 μ to 24 μ, at intervals of 1 μ for the wavelength interval from 4 μ to 10 μ, and at 2 μ intervals thereon to 24 μ. The calculations have been carried out to values of α (α is the ratio of sphere circumference to wavelength) of 30. For values of the Mie absorption parameter, k, greater than approximately 0·10, values of the normalized absorption cross‐section are shown to have a maximum which exceeds unity by an appreciable amount. In all instances, the values of the normalized scattering and total attenuation cross‐sections exceed unity over most ranges of α considered, the excess over unity being greater for small values of absorption. Some rough calculations are made comparing Mie absorption coefficients with those for bulk‐water absorption at the same wavelength.
An 18th century series of pressure readings in Dublin
Authors: Dixon F. E.
Published: February 2007

Measurements of barometric pressure between 1749 and 1765 in Dublin are converted to millibars and the monthly mean values extracted.
The representation and analysis of vertical distributions of ozone
Authors: Godson W. L.
Published: February 2007

A new diagram is proposed for the representation and analysis of the vertical distribution of ozone – the ozonagram with basic coordinates of ozone partial pressure and the logarithm of total pressure. It is shown that only this diagram satisfies a set of seven criteria devised to meet all dynamical, analytical and graphical requirements. Convenient symbols and units are also proposed for various ozone parameters.

The ozonagram is applied to the representation and analysis of umkehr data for the Canadian stations of Moosonee and Edmonton (Mateer and Godson 1960). The basic features of the seasonal variations are illustrated, in particular, the relative roles of the lower and middle stratosphere, the latter being largely responsible for the annual ozone maximum. The effects of changes in air mass are investigated for several seasons, but no unique pattern emerges. Even when middle‐stratosphere temperatures do not change significantly, it appears that middle‐stratosphere ozone concentrations do change, in a variable manner. In the absence of dynamic activity in the middle stratosphere, however, the Normand‐Reed mechanism can be substantiated.
The description of rain by means of sequential raindrop‐size distributions
Authors: Dingle A. N. , Hardy K. R.
Published: February 2007

The photoelectric raindrop‐size spectrometer has made possible the resolution of drop‐size spectra in natural rains to 1‐min intervals of time. Characteristics of the drop‐size spectra thus obtained and their time‐sequences are discussed. Various factors affecting the development of raindrop‐size distributions are discussed as they relate to the observed distributions.

Qualitatively it is indicated that the outstanding observed characteristics of the drop‐size distributions for moderate‐ to high‐intensity rains are primarily attributable to wind‐shear and gravity sorting at the onset of rain and to aerodynamic break‐up and impact splashing of drops, and that predominance of the coalescence or of the Bergeron‐Findeisen process of raindrop formation may be indicated by features of the ground‐level drop‐size distributions.
Aircraft observations near jet streams
Authors: Briggs J. , Roach W. T.
Published: February 2007

The results of an analysis of 22 flights through jet streams by aircraft of the Meteorological Research Flight are presented. The average distributions of wind speed, vertical and horizontal wind shear, potential temperature, water vapour, cirrus cloud and ozone are obtained in relation to the jet core, and are discussed in relation to existing literature on jet streams.

A particular feature observed on a few flights was the apparent protrusion of a tongue of stratospheric air contained within well‐marked frontal boundaries into the baroclinic zone found below and on the low‐pressure side of the jet core. Occurrences of high‐level turbulence are related to various parameters, and the primary importance of vertical wind shear indicated. It is suggested that clear‐air turbulence may play a major role in the erosion and eventual disruption of this upper frontal zone.
Gravity‐wave dispersion under wind shear in two model atmospheres
Authors: Ramm Pauline , Warren F. W. G.
Published: February 2007

The dispersion of an initial disturbance in two model incompressible atmospheres is investigated. Subsequent variations in the ground pressure are plotted and some general features noted.
The electrification of freezing water droplets and of colliding ice particles
Authors: Evans D. G. , Hutchinson W. C. A.
Published: February 2007

When supercooled drops of diameter 1·3 mm were nucleated at — 0·2$C and froze in an environment at — 15$C and fragmented, the average charge on positive residues was 1·5 × 10−3 e.s.u., and on negative residues — 2·2 × 10−3 e.s.u. The charges were comparable with those found in similar measurements by Mason and Maybank but were usually far too large to be accounted for by the Latham‐Mason temperature‐gradient theory.

When ice crystals differing in temperature by up to 10$C were brought into momentary contact, any charge produced was less than 10−4 e.s.u. This result is not inconsistent with the Latham‐Mason theory and does not confirm the much larger values reported by Reynolds et al.
Experimental determination of collection efficiencies for small water droplets in air
Authors: Woods J. D. , Mason B. J.
Published: February 2007

This paper describes measurements of collection efficiencies for gravitational collisions between water drops of radius R = 30 to 55 μ and saline droplets of radius r = 1 to 12 μ. the results agree quite well with those obtained earlier by Picknett for drops of R = 30, 40 μ and also with the collision efficiencies computed by Hocking, Mason and Shafrir and Neiburger except that, for values of r/R < 0·1, the experimental values are consistently higher than the calculated values and fail to show the sharp cut‐off predicted by theory. the experiments support Hocking's prediction that drops of R ⩽ 18 μ will fail to collect droplets of smaller size.
Noctilucent clouds: A steady‐state model
Authors: Charlson R. J.
Published: February 2007

A simple model of a noctilucent cloud is developed leading to requirements for a steady‐state cloud. The sizes achieved by particles falling through a supersaturated layer and the mass budget of the cloud are considered. The necessity of an updraught to explain the persistence of the clouds is discussed.
Note on the computation of heat sources and sinks in the atmosphere
Authors: Shaw D. B.
Published: February 2007

The contributions of various transport terms in the thermodynamic energy equation are calculated over the Northern Hemisphere for the four seasons. Local heating is found to be an order of magnitude less than the other terms. The computed fields due to mean horizontal motion cover a more extensive area than those of earlier investigations and extend over the Northern Hemisphere from surface to 100 mb for the four midseason months. An attempt to represent the effect of horizontal transient disturbances by relating it empirically to the mean temperature field is found to be unsatisfactory; direct computations are made of the eddy contribution over a large part of the hemisphere, for three successive winters and one summer. An estimate of the contribution due to vertical motions, both mean and transient, is obtained indirectly as the difference between results of the present study and those of earlier independent investigations of atmospheric heating.
Temperature and humidity changes in the lowest few thousand feet of atmosphere during a fine summer day in Southern England
Authors: Zobel R. F.
Published: February 2007

Aircraft observations are used to examine the temperature and humidity changes beneath a subsidence inversion on a fine day in Southern England, including some details of the breakdown of a nocturnal radiation inversion. The findings in regard to the latter are in substantial agreement with those of Izumi (1964). Consideration of the heat and moisture balances of the surface and of the layer of air beneath the subsidence inversion leads to the conclusion that daytime convection causes penetrations of the inversion which are compensated by the downward movement of air of higher potential temperature from above the inversion. In the case studied, the daytime rise in temperature of the air column beneath the inversion was found to be largely due to this downward flux of heat and to direct absorption of solar radiation, the heat flux from the surface being relatively small, since the net radiative flux was mainly expended on evaporation of water.
Evidence for a longer period tidal oscillation in the tropical atmosphere
Authors: Brier G. W.
Published: February 2007

A tidal explanation is offered for the biennial oscillation observed in the stratosphere. Evidence is presented that the variations in the amplitude of the 12‐hour pressure oscillation (S2) at Batavia are significantly correlated to the changes in the magnitude of the luni‐solar tidal forces, which can be shown to have a period of approximately 27 months in tropical latitudes. The suggestion is made that the forces producing an amplification of the S2 oscillation are linked to the circulation changes through mechanisms involving increased cloudiness and precipitation.
Examination of certain terms appearing in Reynolds' equations under unsteady conditions and their implications for micrometeorology
Authors: Bernstein A. B.
Published: February 2007

Reynolds' equations are generally valid only when the bar operator represents an ensemble average. Such averages are rarely calculated in practice, the usual approach (especially in micrometeorology) being to calculate a time average instead. When conditions are at all unsteady, this practice necessitates consideration of additional terms in the expression for the Reynolds flux. It is shown, with the aid of a series of rapid‐response measurements of wind and temperature, that these terms are not necessarily negligible and that under unsteady conditions the complete Reynolds flux expression may differ considerably from the quantity generally computed; also, the vertical gradients of the two quantities will differ. A quantitative criterion of steadiness is proposed and is shown to be highly correlated with the difference between the complete Reynolds flux and the quantity usually calculated.
Antarctic stratospheric warming reviewed in the light of 1967 observations
Authors: Phillpot H. R.
Published: February 2007

Unlike the Northern Hemisphere where a number of extremely well documented case studies to very high levels facilitate the study of polar stratospheric warming, most investigations so far in the Southern Hemisphere have been directed mainly to the 100 mb, or occasionally 50 mb level. In 1967 it was possible to draw a series of daily 30 mb contour charts through the spring period, and 30 mb isotherm charts for the month of October over the Antarctic. The contour charts showed that the polar vortex: changed little in depth until the end of September then filled steadily; was initially single centred, became double‐centred, then finally single centred again; developed a double‐wave pattern, the perturbations moving progressively and regularly around the vortex. The movement of these waves was accompanied by short period, but marked, temperature changes at a given point (warm ridges and cold troughs), but even after the major warming was completed at this level over the continent, the circulation was still predominantly cyclonic. From the limited information available it appears that in 1967 the short period temperature changes may have been more pronounced than in some earlier years, but the general warming trend was normal. Wave movement around the polar vortex could also be detected in an autumn and winter season, and apparent mid‐winter stratospheric warmings previously reported or observed may be ascribed to the passage of migratory warm ridges, although this explanation is not advanced for the mid‐winter warming event inferred over McMurdo in 1963.
The lunar and solar semidiurnal variations of barometric pressure at Copenhagen, 1884–1949 (66 years)
Authors: Chapman S.
Published: February 2007

Sixty‐six years of bihourly barometric data for Copenhagen (55°·7N) are used to determine the lunar atmospheric tide there, L2 (p), and also the harmonic components Sn of the solar daily barometric variation S (p), for n = 1, 2, 3, 4, For L2 (p) seasonal means are given as well as the annual mean; for S2 (p) monthly, seasonal and annual mean values are given. The determinations are made for groups of days with different upper limits of range, 6·0 microbars (μb) and 8·7 ph, as well as for all days. It is shown that it is advantageous to exclude the days of larger range from the determination of L2 (p). Days of larger range are most frequent in winter. At that season, for days of smaller range, the mean pressure is higher than in summer.

The 66‐year mean annual value of L2 (p) is 10·3 sin (2r + 87°·3) μb, with probable error 2·5 μb; for S2 (p) it is 225 sin (2t + 130°·8), with probable error 2·8 μb; here r and t denote respectively lunar and solar mean local time. Thus, in amplitude, S2 is 21·9 times L2, and in phase S2 exceeds L2 by 43°·5; L2 and S2 at Copenhagen vary seasonally in different ways; in both cases these variations are similar to those observed elsewhere in northern Europe. The corresponding amplitudes for Oslo (59°·9N), found by Haurwitz and Cowley (1967), are somewhat smaller, as might be expected.
Microwave observations of sea state from aircraft
Authors: Nordberg W. , Conaway J. , Thaddeus P.
Published: February 2007

Measurements of the thermal radiation emitted by natural water surfaces at a wavelength of 1·55 cm have been measured from aircraft at up to 12 km altitude.

The dependence of the radiation on surface roughness is studied in view of its possible importance to satellite observation of sea state.
On the interaction between the stratosphere and troposphere during the warming of December 1967‐january 1968
Authors: Miller A. J. , Johnson K. W.
Published: February 2007

Calculations of the transfer of kinetic energy from the troposphere to the stratosphere by means of the pressure‐interaction term are carried out for the mid‐winter stratospheric warming of 1967‐1968. This term is computed in the wave number domain for the 100 mb level by means of the Eliassen and Palm (1960) approximation. There appears to be a distinct correlation between the stratospheric kinetic energy per wave number at the 10 mb level and the energy transfer by that wave number at the 100‐mb level. A comparison of the magnitude of the energy flux for 1963 versus that for this later warming suggests that this term is of the same order as the remaining terms in the kinetic energy equation calculated by Perry (1967). Results obtained using this approximation appear to give good agreement with those obtained by direct calculation of the vertical velocity field.
New lag associations between North Atlantic sea temperature and European pressure applied to long‐range weather forecasting
Authors: Ratcliffe R. A. S. , Murray R.
Published: February 2007

A feed‐back relationship, at least in the statistical mean, between Atlantic sea surface temperatures on the one hand and monthly atmospheric circulation anomalies on the other hand, is demonstrated for the north‐east Atlantic and western Europe. The key area in the Atlantic is a wide area south of Newfoundland; colder than usual ocean surfaces in this area are shown to be associated with blocked atmospheric patterns the following month over northern and western Europe while a warmer than usual ocean in the same general area favours more progressive synoptic types to follow. Month to month changes in this general relationship are described in some detail and the application to long‐range forecasting in the British Isles is discussed. One other pattern of Atlantic sea surface temperature anomaly is also described and associated with atmospheric circulation patterns to follow.

Possible inter‐relationship between the Atlantic and Pacific Oceans in respect of the effects of ocean surface temperatures on circulation patterns is also briefly considered.
Surface exchanges of sensible and latent heat in a 10‐level model atmosphere
Authors: Gadd A. J. , Keers J. F.
Published: February 2007

This paper describes a representation of the distribution of sensible and latent heat from the surface through the atmospheric boundary layer which has been formulated for use in a 10‐level primitive equation model atmosphere. The transfer process is represented in two parts : (i) the transfer of energy across the Earth's surface into the lowermost 100 mb layer of the model atmosphere; and (ii) the subsequent redistribution of this energy through two or more such layers by small‐scale convection. The fluxes of energy across the surface are calculated using empirical ‘bulk aerodynamic’ relationships. In land regions consideration of the energy balance at the surface is also necessary, and diurnal variations of radiation are taken into account. The redistribution of energy by small‐scale convection is represented by convective adjustments which ensure that a certain neutral lapse rate of temperature is never exceeded. Some results of the incorporation of these effects into the 10‐level model are described.
The water‐vapour infra‐red continuum
Authors: Bignell K. J.
Published: February 2007

All published work on the water‐vapour continuum in the region 8 μ to 50 μ is reviewed in the light of some new experimental results in the 11 to 21 ‐μ region. This new work employed a 15.5 m multiple‐reflection cell, giving total path lengths up to 500 m, and a high‐resolution (1–2 cm−1) grating spectrograph. Control of temperature (20–40°C), and water‐vapour partial pressure (3–35 mb) allowed simulation of tropospheric conditions and their extension to rather higher humidities, but the total pressure could not be varied from atmospheric.

The results suggest that two mechanisms of absorption are involved. One of them is almost certainly the foreign‐broadening of water‐vapour lines and it is responsible for most of the continuum absorption noted by previous workers. The origin of the other is not clear; it gives rise to absorption which increases with partial water‐vapour pressure, e, equalling the foreign‐broadened component at e ∼ 15 mb. This behaviour was first reported by Bignell, Saiedy and Sheppard (1963) who then attributed it to self‐broadening of H2O lines. However, the present more sensitive work casts doubt on this interpretation because the absorption is found to have a negative temperature dependence of 2 per cent per °C over the range 21° to 45°C, which is greater than that of any water‐vapour line. Absorption of the same type, though weaker, is present near 4 μ.

Reinterpretation of previous open‐air measurements in atmospheric conditions ranging from warm and damp to cold and dry shows that the systematic differences they exhibit might be a manifestation of the new absorption.

No firm explanation can be given, but the possibility of continuum absorption by the recently reported water dimer molecule (H2O)2 should be investigated.
The analysis of a hailstone
Authors: Macklin W. C. , Merlivat L. , Stevenson C. M.
Published: February 2007

An analysis has been made of the bubble and crystal structure and of the isotopic composition of a hailstone from a severe storm which occurred near Cardiff on 1 July 1968. A trajectory for the stone has been deduced from the isotopic data which is consistent with its crystal and bubble structures. Updraught profiles have been calculated also and are in reasonable agreement with those inferred from the extended parcel theory.
Concentrations in mountain areas of particles released at low elevations
Authors: Gagin A. , Neumann J.
Published: February 2007

Concentrations in the air of ice nuclei active at − 15°C have been measured in Jerusalem, Israel. It is found that the highest concentrations occur almost always on days when the mixing depth in the lower atmosphere over the coastal area to the west reaches Jerusalem's elevation (750–830 m) or an elevation not exceeding a few hundred metres above it. Most of the high concentrations and the mixing depths of about 1,000 m occur in the warm season when a low‐level subsidence inversion is a near‐permanent feature of the atmosphere.

The results are consistent with the hypothesis that most of the particles originate in low‐level areas upwind of the city having been carried up to Jerusalem's altitude mainly by vertical mixing.
Tropical disturbances and the general circulation
Authors: Bates J. R.
Published: February 2007

The role of the Tropics in the general circulation of the atmosphere is discussed, with emphasis on the rising branch of the Hadley cell. The rising motion takes place largely in organized tropical disturbances and in the Intertropical Convergence Zone. To understand these systems, it is necessary to parameterize the latent heat release by cumulonimbus clouds in terms of the large‐scale flow. The various methods which have been devised to accomplish this are outlined and the results of large‐scale models incorporating these methods are discussed.
Systematic deviations of clear sky atmospheric thermal radiation from predictions of empirical formulae
Authors: Idso S. B.
Published: February 2007

Four replicated measurements of atmospheric thermal radiation were obtained every half‐hour of seven clear days during February at Phoenix, Arizona. All indicated the existence of systematic deviations from the predictions of empirical formulae. By invoking an explanation for the existence of such deviations recently given by Paltridge (1970), the times of occurrence of these deviations could be predicted quite accurately.