bluuebunny/crossref_metadata_2025 huggingface dataset:
Reliability of speed of contraction and endurance dynamometric measurements of the pelvic floor musculature in stress incontinent parous women
Authors: Morin M. , Dumoulin C. , Gravel D. , Bourbonnais D. , Lemieux M.‐C.
Published: February 2007

Aims

To evaluate the test–retest reliability of dynamometric measurements of the pelvic floor muscles (PFM) during speed and endurance tests.

Methods

Nineteen parous women suffering from stress urinary incontinence (SUI) participated in the study. Two PFM evaluation sessions were conducted using the dynamometric speculum. For the speed test, the women were instructed to contract maximally and relax as quickly as possible during a 15‐s test period. The speed of contraction was quantified by the rate of force development of the first contraction and the number of contractions performed. The maximal strength value attained during the speed test was also extracted from the curves. For the endurance test, the subjects were asked to maintain a maximal contraction for 90 s. The normalized area under the force curve was utilized as the endurance parameter. The reliability of the data was evaluated using the generalizability theory. Two reliability estimates were calculated, the dependability indices (Φ) and the standard error of measurement (SEM), for one measurement session involving one trial.

Results

The indices of dependability obtained indicate that the reliability of the speed of contraction and endurance parameters are good (Φ=0.79–0.92). The corresponding SEMs were 1.39 N/s, 1 contraction, 1.00 N, and 298%*s for the rate of force development, number of contractions, maximal strength and normalized area, respectively.

Conclusion

This study indicates that the speed of contraction and endurance parameters possess good test–retest reliability. The inclusion of these parameters in the PFM assessment is therefore highly recommended for assessing changes in PFM in incontinent women. Neurourol. Urodynam. 26:397–403, 2007. © 2007 Wiley‐Liss, Inc.
Minimally‐invasive electrical stimulation of the pudendal nerve: A pre‐clinical study for neural control of the lower urinary tract
Authors: Yoo Paul B. , Grill Warren M.
Published: February 2007

Aims

Electrical stimulation of afferent pudendal nerve fibers can evoke sustained bladder contractions (SBC) in cats, yet evidence of therapeutic efficacy in human subjects is lacking. This pre‐clinical study was undertaken to test the hypothesis that robust bladder contractions can be generated with a minimally‐invasive needle electrode.

Materials and Methods

In seven adult cats, triggered electromyographic (EMG) signals from the external anal sphincter (EAS) were used to minimize the needle‐to‐nerve distance; while reflex bladder contractions were recorded as 20‐sec trains of current pulses of varying amplitude (threshold to 10 mA) and frequency (1–100 Hz) were applied to the nerve. This stimulation paradigm was repeated at successively greater needle‐to‐nerve distances (0.5 cm intervals) and also at different electrode positions along the nerve.

Results

Electrophysiological access to the pudendal nerve was consistently achieved, as indicated by the average threshold for EAS activation (0.31 ± 0.19 mA). Using different combinations of stimulus amplitude and frequency, robust SBCs were evoked in every experiment. More rostral electrode positions exhibited stimulation amplitudes and corresponding maximum bladder pressures (0.68 ± 0.36 mA and 25.3 ± 3.5 cmH2O, respectively) that were comparable to those of more invasive stimulation methods.

Conclusions

The needle electrode provides a minimally‐invasive approach that will enable the study of reflexes mediated by pudendal afferents in humans, and allow pre‐operative testing before implanting a permanent device. Neurourol. Urodynam. 26:562–569, 2007. © 2007 Wiley‐Liss, Inc.
Gene polymorphisms and susceptibility to coronary artery disease
Authors: Shah Svati H.
Published: February 2007

As pediatric cancer survivors age, long‐term cardiovascular complications related to chemotherapeutic toxicities, as well as development of premature coronary artery disease (CAD) from radiation and increased prevalence of CAD risk factors such as obesity, are likely to become more prevalent. Despite advances in our understanding of CAD in the general population, a large amount of the variance in development of disease is unexplained. Given the strong heritability of CAD, some of this may be attributable to genetics. Premature CAD in particular segregates in families, and twin studies have shown that the genetic contribution is greater in premature CAD. In this article, we present a brief review of the literature on the genetics of CAD. Over 30 monogenic disorders feature CAD phenotypes. Recently, however, interest has shifted to understanding the genetic variation contributing to common, complex disease, where disease risk is polygenic and characterized by environmental factors, and gene–environment interactions. CAD epitomizes such a disease, and highlights the inherent difficulties in understanding the underlying genetic architecture of such diseases. Long‐term cardiovascular complications in patients who survive pediatric cancers result in significant morbidity and mortality in this population. Clinicians need to be aware of screening and treatment strategies for primary and secondary prevention of cardiovascular complications in this group. Further research is necessary to define the epidemiology and risk factors of premature CAD in survivors of pediatric cancers, and to determine whether candidate genes for cardiovascular disease in the general population are also susceptibility genes in this vulnerable population. Pediatr Blood Cancer 2007;48:738–741. © 2007 Wiley‐Liss, Inc.
A rapid TLC autographic method for the detection of glucosidase inhibitors
Authors: Salazar Mario O. , Furlan Ricardo L. E.
Published: February 2007

A new bioautographic assay suitable for the localisation of β‐glucosidase inhibitors present in a complex matrix is described. Enzyme activity was detected using esculin as the substrate to produce esculetin, which reacts with ferric ion to form a brown complex. Copyright © 2007 John Wiley & Sons, Ltd.
Disconnection of the organic moiety in chromium and tungsten complexes [(dithiin)M(CO)5]
Authors: Granados Alejandro M. , Fracaroli Alejandro M. , Kreiker Jeronimo , de Rossi Rita H.
Published: February 2007

The reaction of 5‐alkylthio‐3H‐1,2‐dithiole‐3‐thione derivatives with Fischer alkoxy carbenes gives 1,3‐dithiin dithioorthoesters derivatives complexed with M(CO)5 (M = Cr or W). We report here that the dithiin derivative free of metal can be obtained by ligand exchange using acetonitrile, methanol, phenyl methyl sulfide or (Ph)3P. Methanol gives the best results from a preparative point of view. The reaction with acetonitrile was shown to be reversible and the kinetic of ligand exchange and the activation parameters were determined. From these data it is concluded that the mechanism is predominantly dissociative for M = Cr and it has some contribution of the associative mechanism for M = W. Copyright © 2007 John Wiley & Sons, Ltd.
Electric fields below clouds
Authors: Chalmers J. A.
Published: February 2007

It is shown that the discrepancy between the measured electric fields below clouds and the calculated fields cannot be removed by considering either the charges of rain drops or vertical air currents to decrease the space charge.
The diurnal variation of warm‐frontal precipitation and thunderstorms
Authors: Dexter R. V.
Published: February 2007

1. Inasmuch as there is a direct relation between the amount of potential instability in the warm air and the amount of precipitation subsequently produced as the air ascends the warm‐frontal surface, the maximum precipitation should be experienced at the time when the maximum potential instability is being realized.

Maximum potential instability is developed in the warm air in contact with the ground in the late afternoon. But this instability is realized only after lifting, so that the time of maximum rainfall is postponed for six to ten hours, occurring in the late evening and early morning. This maximum reaches the edge of the precipitation area eight or more hours after development of the instability, thus increasing the width of the area in the late night and early morning hours. The development of cyclonic curvature which accompanies the realization of the potential instability in the ascending current may also be a contributing factor.

2. Because latent instability is associated with potential instability, since if the latter is present, the former may develop through lifting, the maximum number of warm‐frontal thunderstorms likewise occurs in the late evening or early morning, six to ten hours after maximum potential instability has developed.
Some properties of geostrophic motion
Authors: Westwater F. L.
Published: February 2007

The properties of a field of pressure which permits of persistent geostrophic motion (ignoring variations of density and latitude) are discussed. It is shown that it is in general impossible to separate the translation effect from the isallobaric effect when considering development of the pressure field.
The temperature characteristics of different classes of air over the British Isles in winter
Authors: Belasco J. E.
Published: February 2007

Hitherto, for synoptic and climatic purpose, means of temperature at the surface, and in the upper air, have been obtained without regard to the different classes of air masses, the means being for all masses combined.

With the object of obtaining a greater insight into the structure of the atmosphere, it is pertinent to inquire what are the difference between (i) the vertical distribution of temperature, and (ii) the temperature near the surface of the earth, in the different classes of air which cross the British Isles.

This investigation gives, for the winter season (December, January, and February combined), for 12 different classes of air over the British Isles: (i) the average and extreme temperatures, the lapse rates and the degree of thermal stability at a number of levels in the atmosphere, and the heights of the 32°F. and 8°F. isotherms; (ii) the daily maximum and minimum temperatures, the mean temperature, and daily range of temperature at the surface at Kew during the 24‐hour period, 0‐24 h., on days when no important change of air mass occurred during this period. The levels in the atmosphere for which values have been obtained are 1,000, 2,000, 3,000, 5,000, 10,000, 15,000, and 20,000 feet. Over 600 upper air ascents, chosen for the most part during the winters of 1930‐31 to 1943‐44, and 1,000 surface maximum and minimum temperatures at Kew during the winters 1924‐25 to 1943‐44 have been used. For comparison, and to obtain an estimate of the changes of temperature and stability, means of temperature at the same levels in the atmosphere were obtained over western Russia in Siberian air, and over the Icelandic and Azores regions in direct polar air and in tropical air. The reality of the difference of temperature between the various classes of air chosen has been examined. A discussion of the physical problems raised in this paper is reserved for another paper.
On the frictional influence of horizontal wind shear on vertical motion
Authors: Priestley C. H. B.
Published: February 2007

It is suggested that a reason for the association between anticyclonic vorticity and subsidence lies in the divergence produced by the frictional forces when a strong horizontal wind shear is present. In particular the region just to the south of a strong westerly upper wind (northern latitudes) is favourable for subsidence.

A case in which such conditions remained steady for five days has been examined quantitatively, and it is found that a subsidence velocity of a few centimetres per second is accounted for by assuming an isentropic turbulent interchange coefficient (K) of 5 × 109 cms2/sec. This is the value found by Rossby and independently by Grimminger in investigation of other phenomena on a similar scale.

The frictional divergence depends on the third space derivative of velocity across the current, and so can only be obtained when the velocity field is mapped in very exact detail. Scope for practical application of this theory in synoptic work is therefore limited.
A theoretical note on some errors in estimating the curvatures of air trajectories and streamlines
Authors: Hogben G. L.
Published: February 2007

This note discusses the theoretical aspects of the errors in measuring curvature due

to taking streamlines as trajectories

to taking isobars as streamlines

to combining these errors by taking isobars as trajectories.

It is shown that, in addition to a scale factor error associated with movement of the isobaric and streamline systems (this has already been noted by other writers), there are errors associated with

The difluence of the isobars and streamlines

The rate of distortion of the systems

The angle between isobar and wind.

By choosing the right place in the isobar and streamline fields some or all of these errors may be avoided. Otherwise any one of them may be significant.
On the application of the richardson criterion to large‐scale turbulence in the free atmosphere
Authors: Petterssen Sverre , Swinbank W. C.
Published: February 2007

A brief report on an investigation into the relationship between the wind shear and the static stability of the air in the layer immediately below the tropopause was presented to the Meteorological Research Committee in October 1942 (Swinbank, M.R.P. 51, unpublished). In the course of the ensuing discussion, members of the M.R.C. suggested that the investigation should be extended to cover the entire troposphere. This has been done particularly with a view to finding empirical relationships between stability and wind shear and comparing these with the results obtained by applying the Richardson criterion to actual observations. A further demand for investigating this problem arose in connection with an investigation of the turbulence conditions that obtain near the tropopause.

In the present investigation use has been made of the reports from the British radio‐sonde stations for the period December 1942 to March 1943. The accuracy of the D/F method of determining the wind in the free atmosphere depends to a large extent upon the geometry of each case, and a tolerance figure is allotted to each observation assessing the accuracy. Only reports of the highest degree of accuracy (i.e. vector errors less than 5 km/hour) have been used in this investigation. In all, 1,556 simultaneous observations of lapse rate and wind shear have been investigated.

The observations have been grouped according to levels, and the results are illustrated in 12 diagrams in which lapse rate is the abscissa and wind shear the ordinate. The diagrams contain also the limiting curve between decrease and increase in turbulence as computed from Richardson's criterion. Since wind observations are made at intervals of 50 millibars, the diagrams represent the observed relationship between the mean wind shear and the mean lapse rate through layers of 50 mb. depth. The limiting curve in these diagrams would then represent the limit between the conditions that determine decrease and increase in the large‐scale turbulence of the atmosphere.

The diagrams show that, with very few exceptions, for any degree of stability the observed wind shear is less than that required by Richardson's theory to cause the turbulence to increase.

If the assumptions underlying the theory were correct and applicable to large‐scale turbulence, the diagrams would indicate that large‐scale turbulence almost invariably tends to decrease. Since this result appears improbable, it is shown that agreement between theory and observation can be obtained by dropping one of the assumptions made by Richardson; namely, that the coefficient.
Dynamical control of atmospheric pressure: II—the size of pressure systems
Authors: Priestley C. H. B.
Published: February 2007

A result from a previous paper (Priestley 1947) indicates the existence of a broad upper limit to the size of pressure systems, and a lower limit to the distance separating the centres of two significant closed pressure systems. The pressure field has thus an inherent scale of pattern which varies with latitude, imposed by the essential geometry and dynamics of atmospheric flow. Orders of magnitude deduced theoretically agree well with experience. The implications contribute to an understanding of the mechanism of the mean global circulation.
Note on the diurnal and semi‐diurnal pressure variation in Rhodesia
Authors: Sellick N. P.
Published: February 2007

The mean annual amplitude and phase of the diurnal and semi‐diurnal waves of barometric pressure at stations in Rhodesia and Nyasaland are given and it is shown that the amplitude of the semi‐diurnal wave, corrected according to Simpson's formula, exhibits a striking uniformity.
Some problems in radio meteorology
Authors: Booker H. G.
Published: February 2007

Refraction of radio waves of wavelength less than about ten metres in the troposphere is a phenomenon usually associated with quite steep inversions of temperature and lapses of humidity within the first few thousand feet of the atmosphere and often within the first hundred feet. A radio ray may be bent downwards with a curvature exceeding the curvature of the earth either by an inversion of temperature exceeding about 5°F./100 ft. or by a lapse of humidity exceeding about 1/2 gm./kg./100 ft., or by a combination of the two. To cause marked unorthodox radio propagation these steep gradients need to be maintained through a layer of atmosphere whose thickness varies from say 50 ft. to 500 ft. depending on the radio wavelength under consideration. Generally speaking, the lower in the atmosphere the gradients occur the more striking is the phenomenon or radio refraction, and steep gradients at heights above about 5,000 ft. are not usually of great interest.

The obvious meteorological phenomena likely to cause radio refraction are nocturnal radiation‐inversions over land, advection‐inversions caused by warm dry air over land moving out over sea, and low subsidence‐inversions. High subsidence‐inversions are not usually a direct cause of radio refraction; their presence may however indicate weather conditions favourable to development of radiation or advection‐inversions.

The meteorological problem is to specify the profiles of temperature and humidity associated with these phenomena at least with sufficient accuracy to state whether the above‐mentioned gradients are exceeded, and if so between what intervals of height. Moreover it is necessary to be able to do this not merely in a special experiment but also from the ordinary data available in synoptic meteorology. It is suggested that the way to do this is to formulate a satisfactory theory of how the profiles of temperature and humidity arise, and then to check the theory carefully by experiment. The upshot should be a means of specifying the profiles in terms of parameters measuring the stability of the air, the windspeed, and so on, and these should be ascertainable from ordinary meteorological data.

The application of the conjugate power‐law theory of eddydiffusion to the problem is described, as well as a comparison which had been made with observed profiles of temperature and humidity. The comparison, although satisfactory in some respects, seems to indicate that the profile‐index involved in the theory shows more signs of depending on the degree to which the diffusion‐process has developed than on the stability of the air. It is suggested that what is required is a theory in which the coefficient of eddy‐diffusion increases linearly from zero at ground level to a maximum at no great height, and then decreases again.
Theory of waves in the lee of mountains
Authors: Scorer R. S.
Published: February 2007

The disturbance in an air current, whose velocity may vary with height, caused by irregularities in the ground, is obtained. For a wave‐like corrugation of the ground of wavelength 2π/k, small enough for the earth's rotation to be neglected, the stream function of the disturbance satisfies Ψ″ – (g/c2 +β) Ψ + (gβ/U2 – U″/U – k2) Ψ = 0(12)

Some circumstances in which waves may have large amplitude only in the lower layers of the atmosphere are described. In order that such waves may occur over level ground in the lee of mountains the parameter l must normally decrease upwards, where l2 = gβ/U2 – U″/U (13)

With two layers, the lower of depth h, these waves can occur if l1 2 – l2 2 > π2/4h2 (17)

Fourier's integral theorem is used to obtain the flow in two instances. Fig. 3 shows the wave due to a single long ridge in a stream in which the wind is stronger at higher levels. Fig. 5 shows the flow of a shallow current descending from a plateau, the air being calm above.

Nodal surfaces, as in Fig. 5, occur only when the depth of the layer exceeds a critical value, depending on the details of wind speed and temperature.

The well‐known cloud phenomena associated with the waves are briefly described in section 6, and in section 7 the effect of isolated mountains rather than long ridges is considered.

The theory is only valid for streamline, dry, isentropic, inviscid. flow in which the disturbance is only a small proportion of the wind velocity.
The vertical temperature gradient in the lower atmosphere under daylight conditions
Authors: Tait G. W. C.
Published: February 2007

A relationship is derived between the vertical temperature gradient in the lower atmosphere during daylight hours and other meteorological quantities. Pyrheliometer records of solar radiation taken simultaneously with temperature gradient measurements gave the empirical relation T1–T2 =(0.4–41) log10 Z1/Z2 where T is the temperature in °F at height Z cm and I the insolation in cal cm−2/min. This equation was converted into a more useful form by expressing the insolation in terms of state of sky, latitude and time. The relationship disclosed was found to be independent of wind speed (at least up to speeds of 24 mi/hr). The data on which the relation is based is confined to observations at Suffield, a semi‐arid locality. A brief discussion of other conditions of exposure suggests that some generality of application may be permissible.
Troughs in the Upper Westerlies and cyclonic developments in the Nile Valley
Authors: El‐Fandy M. G.
Published: February 2007

In the Middle East Area (M.E.) troughs in the upper westerlies are found, generally, at levels over 2 km above M.S.L. intruding into low latitudes as far south as the Northern Sudan (lat. 20° N.). These troughs usually travel eastwards, but tend to trail over the NW. of the Abyssinian Plateau. They also frequently remain stationary for about three days (on the average) over the SE. Mediterranean, owing to the effect of the plateau of Asia Minor.

At the southern limits of these troughs, centres of convergence are usually set up within the westerlies, which have thus extended (at upper levels) into low latitudes, between lat. 22° N. and lat. 15° N. For the purpose of studying them the stream‐line map has been found the most satisfactory; the usual pressure map is of little assistance.

As a rule a cyclone (say of type “A”) tends to form at a centre of convergence, and travels towards the NE., NNE., or even N.; the northward movement of the cyclones being due to the tendency for them to move towards the “centres” of the quasi‐stationary troughs over the SE. Mediterranean. Cyclones may eventually appear on the surface synoptic charts as shallow areas of low pressure.

Another set (say of type “B”) of upper‐air cyclones, which move south‐westwards, tends to form farther south by the setting up of wave‐like perturbations in the usual E.–NE. upper current of the atmosphere of the Central Sudan. These perturbations appear at the time of re‐establishment of the E.–NE. current over the N. Sudan with the northward retreat of the westerlies, extend into low latitudes, and generally, when an upper‐air cyclone of type “A” has reached the M.E., another cyclone of type “B” develops over the East‐Central Sudan.

The analysis has some value in forecasting upper winds on the Cairo—Khartoum air‐route and the local weather associated with these cyclones, and also in studying the general circulation in these latitudes, more especially the characteristic features of these cyclones.
The upper‐level flow‐structure near typhoons
Authors: Thompson B. W.
Published: February 2007

From flow charts drawn at the Royal Obsrvatory, Hong Kong, it appears that typhoons commonly develop at airflow discontinuities with Easterlies to the north and Westerlies to the south. Others probably develop within a single airflow, notably N. Pacific Trades, and perhaps N. Indian Westerlies. Typical streamlines in the neighbourhood of typhoons in different localities are presented, and the development and relations of the associated flows are discussed.
The apparent diurnal temperature variation in the lower stratosphere
Authors: Kay R. H.
Published: February 2007

Two years of upper‐air data from the four daily radiosonde ascents from five stations in the British Isles are analysed for the pressure levels 150 mb, 100 mb and 80 mb ‐ some 14,000 ascents in all.

The apparent diurnal temperature changes are discussed and the need is shown for further experimental evidence concerning the reality of the measured high‐level daylight temperatures. The observed daylight heating is too great to be caused by the absorption of radiation and must either be dynamical in origin or due to radiation error of the thermometer element in the radiosonde. From 1948, the times of ascent are suitable for computing the nocturnal cooling throughout the year, independent of radiation error. The temperature falls during the night by about 0.05°C hr−1 at these levels, the sort of change to be expected if radiative processes predominate.

The apparent rate of change of temperature closely following sunrise and just preceding sunset is about ten times more rapid than the nocturnal cooling.

It is concluded that the amplitude and rate of the apparent variations of temperature measured in daylight ascents should be treated with reserve until further experimental evidence as to their reality is available.
An essay on the general circulation of the atmosphere over South‐East Asia and the West Pacific
Authors: Thompson B. W.
Published: February 2007

The major airflows between the surface and 10,000 ft are studied for the area between Japan and the equator and longitudes 100°E. to 150°E., and a description is given of upper‐level influences which have not been apparent hitherto since only surface analyses were prepared before World War II. Convergence zones between airflows near the equator take the place of the fronts of high latitudes.

The traditional theory of the intertropical front of summer is inapplicable to the region and a new concept, developed from observations, is described of an impermanent intertropical convergence zone formed by the occurrence of localized clockwise eddies in equatorial regions which bring southern hemisphere air across the equator and into contact with that to the north. If considered in relation to the West Pacific the traditional intertropical front of India is shown to be in reality part of the West Pacific polar front.
Dynamical aspects of some simple frontal models
Authors: Sawyer J. S.
Published: February 2007

The dynamics of the motion at an idealized frontal surface are considered theoretically. For this purpose the front is treated as a simple discontinuity of density, but it is assumed that horizontal and vertical gradients of temperature and wind may exist within the air masses. It is shown that at a front of this character between two non‐homogeneous air masses there must be a discontinuity of vertical velocity at the frontal surface, i.e., there must be up‐sliding or down‐sliding. The discontinuity in vertical velocity is related to the gradients of wind in the two air masses and is shown to be of a similar magnitude (or only slightly smaller) than the vertical velocities believed to occur in frontal regions.
Structure of the upper westerlies; a study of the wind field in the eastern Atlantic and western Europe in September 1950
Authors: Murray R. , Johnson D. H.
Published: February 2007

On the basis of 60 cross‐sections over western Europe and the northeast Atlantic, two for each day of September 1950, it is concluded that:

Daily charts are given showing the jet axes and intensities at 300 mb superimposed on the surface analysis.

The westerlies always contain one or more wind maxima in the upper troposphere with structure broadly similar to that described by other writers on jet streams but with much variety of intensity and velocity profile.

The mean horizontal wind shear on the warm side of the jet stream is about two‐thirds of that on the cold side where it averages 20 kt/100 mi and may exceed 100 kt/100 mi.

The geostrophic relation gives a broadly correct representation of the true winds.

There is a broad connexion between fronts and jet streams, but the relationship is often less simple than that suggested in published work hitherto. Divided jets, distinct double jets and other complexities arise.
Precipitation growth in stratiform clouds
Authors: Wexler R.
Published: February 2007

The radar observations along the vertical of precipitation in stratiform clouds are compared with the theoretical growth rates of ice crystals in such clouds. The analysis indicates that no liquid water exists in these clouds at levels above about −5°C. The variation of signal strength from the −3°C level through the ‘bright band’ and the drop‐size distribution in the rain measured at the ground can be satisfied by reasonable assumptions concerning the coalescence of ice crystals.
Observations of the westerlies over the sea
Authors: Sheppard P. A. , Charnock H. , Francis J. R. D.
Published: February 2007

Observations of wind speed and direction at 50 m intervals of height in the first few hundred metres have been made over the NE. Atlantic during 10 winter days of westerly winds. The following results were obtained:

The vertical gradient of wind speed is of the same order at all levels and there is no identifiable transition from a layer of frictional influence to a layer of friction‐free wind.

The wind speed at 300 m was on the average 21 per cent greater than the surface wind, though in 24 per cent of cases the latter was greater than the former. The mean change of direction in the same interval of height was 3·6° veer but the spread was much greater than the mean. On over 30 per cent of cases the wind at 300 m was backed on the surface wind and the speed at the upper level was then only 5 per cent greater than the surface speed.

The vector variation of wind velocity with height in the layer 200–500 m is accountable as thermal wind.

Turbulence of scale greater than about 10 min is of order 10 per cent of the mean motion and increases on average with height.

The mean inclination of the surface wind to the isobar is not more than 1° or 2° and is more likely to be towards high pressure than low.

It is inferred that the classical conception of the frictional boundary layer in a barotropic atmosphere has little validity in the atmosphere over the sea. In particular the shearing stress in the first few hundred metres of the westerlies probably varies only slightly with height and may increase if the thermal wind is strong. Measurement of surface drag by the method of frictional geostrophic departure is hardly possible in the baroclinic westerlies.
Precipitation streaks as a cause of radar upper bands
Authors: Browne I. C.
Published: February 2007

Several workers have reported enhanced radar echoes, from regions well above the freezing level, in layer‐type rain clouds. Usually, there is a decrease with time in the height of these ‘upper bands,’ as Bowen has called such enhanced echoes. This paper describes an investigation into upper bands which has been made at Cambridge, using a 3‐cm radar with a vertically directed beam.

The mean downward velocity of upper bands at a height 9,000 ft above the freezing level is found to be about 20 ft/sec, the velocity generally decreasing systematically with time. Such velocities are much greater than the rate of fall of the ice particles which are shown to be responsible for the upper‐band echoes, which, it is suggested, are produced by precipitation streaks in a region of vertical wind shear. A simple theory is worked out which gives the apparent rate of fall of an upper band in terms of vertical wind shear, the horizontal wind speed near the cloud top, and the terminal velocity of the ice particles forming the precipitation streak. Measured values of the fall speed of upper bands agree reasonably well with those predicted by this theory.

A previous theory of upper bands (Bowen 1951) is shown to be untenable, though it is possible that the upper bands observed by Bowen in Australia have a different origin from those observed at Cambridge. It is proposed to make further observations to settle this question.
A record of the micro‐structure of a cold front
Authors: Samuel D. R.
Published: February 2007

A record is presented showing the fine structure of wind speed, azimuth and inclination, temperature and water‐vapour pressure taken over a five‐minute period within which a cold frontal passage occurred. A particular advantage of the method of recording, using rapid‐response instruments, is the graphic illustration provided of the extreme sharpness of the front. The transition zone, estimated to be 70 m in horizontal extent, passed in 8 sec, during which time the temperature fell 5°C and the water‐vapour pressure increased by 2 mb.

The record, together with two others taken shortly before and after, has been analysed and the results, including the mean vertical velocities, the vertical eddy fluxes of heat, water vapour and momentum, and the K values for heat are presented. Direct evidence is submitted of the vertical eddy transfer of heat, water vapour and momentum through the transition zone.
Note on the reflection of diffuse daylight from still water
Authors: Middleton W. E. Knowles
Published: February 2007

The luminous reflectance of still water for the light from an overcast sky is found to be less than the commonly accepted value (R = 0·066), because such skies are brighter at the zenith than at the horizon. For a sky three times as bright at the zenith as at the horizon, the value R = 0·051 is computed.
The variation of the turbulence spectrum with height under superadiabatic conditions
Authors: Panofsky H. A.
Published: February 2007

A crude spectral analysis of vertical kinetic energy, heat flux and Reynolds stress is presented. It is shown that the relative contribution of high‐frequency eddies to the fluxes and energy decreases with height, whereas the relative importance of long‐period eddies increases with height.
Rainfall over Egypt
Authors: Soliman K. H.
Published: February 2007

The problem of rainfall over Egypt has been investigated.

The distribution of annual amounts of rainfall is given and remarkable variations along the Mediterranean coast are discussed.

Winter is the season of rain in the north of Egypt, but in the south (Upper Egypt), two main seasons are found, namely, May and October.

The diurnal variation of rain of two coastal stations and one inland station is given and discussed.

Warm‐front rain practically does not occur, and cold‐front rain forms only a small proportion of the total amount and occasions of rain. Most rainfall is found to be non‐frontal and associated with upper cold troughs (or lows) which seem to play an important role, not only in Egypt, but all over the Eastern Mediterranean.

Rainy situations in each season are discussed. It is found that, in winter, rain is generally associated with Mediterranean depressions, but when these depressions are not associated with upper cold troughs, they move quickly with very little precipitation. In the spring and autumn, however, rain is usually associated with small desert lows with cold upper lows or troughs.
The onset of turbulence in an elevated layer near sunrise
Authors: Wanta R. C.
Published: February 2007

Abrupt changes at heights 46 m and 125 m above the ground from smooth flow, or flow in which damped eddies occur, to a flow characterized by continuing gustiness are investigated in terms of a critical Richardson number. Such transitions at Upton, N.Y. during the period October‐November 1950 are identified from continuous records of the wind direction. Account is taken of the time for the transition to propagate across the layer. Fourteen transitions during the period studied, all near sunrise, indicate that the (layer) critical number for eddies with periods somewhat less than one minute lies within the range from 1/3 to 1/2. It is suggested that the method used may be applicable to other eddy sizes.
Airborne measurements of the concentration of natural and artificial freezing nuclei
Authors: Smith E. J. , Heffernan K. J.
Published: February 2007

An aircraft‐mounted instrument for measuring the concentration of freezing nuclei in the free atmosphere is described. It has been calibrated and its limitations investigated.

Preliminary observations, in flight, of natural freezing nuclei were made. The temperature at which a given concentration of ice crystals formed on natural nuclei varied markedly from day to day, and increased with altitude.

Measurements in flight of the concentration of freezing nuclei in silver‐iodide smoke, released from a ground generator, are described. The nucleating properties of small particles produced by a hydrogen burner deteriorated very rapidly, while larger particles produced by a kerosene burner were more durable.
A note on the two‐dimensional equation of diffusion in the atmosphere
Authors: Davies D. R.
Published: February 2007

In this paper the shearing advection term, suggested recently by H. Lettau, is introduced into the well‐known two‐dimensional equation formulated by Sutton and Calder in their treatment of turbulent diffusion, and a solution of the ensuing equation is obtained subject to the conditions prescribed by the problem of diffusion from an infinite continuous line source, situated at ground level and orientated in a direction normal to that of the mean wind velocity. The predicted values of cloud height and peak concentration at a distance of 100 m downwind of the source, when compared with previous theoretical values and available experimental results in neutral stability conditions, show that no significant change in theoretical values is obtained by the introduction of Lettau's term, and the order of magnitude of the deviation from the Calder prediction produced by this term is found to be the same at all distances downwind of the source. The shearing advection term may consequently be ignored in the conditions investigated.
Wind stress on a water surface
Authors: Francis J. R. D.
Published: February 2007

Values for the shear stress τ0 of the wind on a water surface, found in seven later experiments, are compared with the data of Francis (1951). Four sets of the new data show that the stress coefficient C = τ0/ϱu2 is not constant, but that it increases somewhat with windspeed u (ϱ = air density). Three sets merely show a large experimental scatter of C, and do not support any consistent law of drag. A theory is also discussed that τ0 is mainly caused by the drag of the small ripples, and not by the drag of the big waves.
THE AIRFLOW OVER MOUNTAINS. A review of the state of current knowledge
Authors: Corby G. A.
Published: February 2007

A brief survey is first given of the observational evidence regarding special airflow effects in the neighbourhood of mountains, as provided by the visual evidence of clouds, the experiences of glider pilots and effects noted by the pilots of powered aircraft. This serves to indicate the phenomena requiring explanation. The review of theoretical studies is confined mainly to the work of Queney and Scorer. Both these authors apply the perturbation method to laminar, isentropic and inviscid flow over an ideal ridge. Queney deals with a uniform airstream (constant velocity and constant stability) and derives streamlines showing wave motions, both vertical and horizontal. Queney's waves are dependent partly on the stability and partly on geostrophic forces, and the order of the wavelength is several hundred km. Scorer, in his treatment, deals with smaller‐scale phenomena, so enabling geostrophic forces to be neglected, and provides for variations of stability and wind shear in the vertical. He finds that realistic wave effects, of the type observed in nature are predicted by the theory provided the variation of stability and wind shear with height is in accord with certain criteria. Past experimental work with models in wind tunnels is briefly considered in the light of what can be deduced from theoretical treatments regarding the conditions for dynamical similarity. More recent work by Long, using a tank containing several layers of immiscible liquid to simulate a density gradient is referred to briefly; this technique appears to have promise. A comprehensive field study by Forchtgott, who wed teams of gliders, is summarized. From his observations, Forchtgott has built up a theory of the flow patterns which occur in the lee of mountains. The main value of Forchtgott's work lies in the practical support it provides for some of the results deduced by perturbation theory and in throwing light on the nature of non‐laminar flow patterns which cannot be dealt with by existing theoretical treatments. In a concluding section, aviation applications of existing knowledge on this subject are referred to briefly. The criteria have some practical value for forecasting purposes.
The microwave properties of precipitation particles
Authors: Gunn K. L. S. , East T. W. R.
Published: February 2007

The theory of scattering and attenuation by rain, snow and cloud is reviewed and theoretical results are presented in the form of equations, tables and graphs, so that the radar response to meteorological particles can be calculated at six wavelengths (10, 5.7, 3.2, 1.8, 1.24 and 0.9 cm) and various temperatures. Particular emphasis is placed on developments since Ryde's comprehensive paper in 1946. Published experimental results are compared with the theory.

All results computed from the theory are contained in Tables 4 and 5. The attenuation by water vapour and oxygen is given in an Appendix.
Radar echoes from lighting
Authors: Jones R. F.
Published: February 2007

Photographic observations of radar echoes received from lightning are given and are used to suggest a possible distribution of the electric charge within a thunderstorm cloud.
Annual rainfall areas of southern England
Authors: Gregory S.
Published: February 2007

This paper attempts to define areas throughout which the fluctuation of annual rainfall is relatively uniform. A general pattern is defined on the basis of graphs of ten‐year running means, and a more detailed pattern is presented from a consideration of individual yearly values of exceptionally high and exceptionally low rainfall. A comparison of the results obtained by these two methods is then made to enable the relative validity of the several areas defined to be assessed.
The development of lightning discharges
Authors: Pierce E. T.
Published: February 2007

The interpretation of experimental observations, described in a preceding paper, of the electrostatic field‐changes due to lightning flashes, is considered. It is found that almost all the recorded field‐changes can be most simply explained in terms of leaders carrying negative charge and originating in the lower part of a thundercloud. Those that reach the ground are succeeded by return strokes. It is considered that both leaders and return strokes consist of a central core surrounded by an envelope of corona; this corona concept, originally advanced by Bruce, leads to a coherent picture of the phenomena observed.
Radar evidence for aggregation and orientation of melting snowflakes
Authors: Mason B. J.
Published: February 2007

Measured values of the relative intensities of the echoes received from the melting zone, the snow above, and the rain beneath suggest that, in general, each snowflake in the melting zone coagulates with one or more (on average, two) others of much the same mass to form horizontally‐oriented aggregates which scatter as oblate water spheroids of mean diameter/axis ratio 4.
Wind stress on a water surface
Authors: Charnock H.
Published: February 2007

The vertical distribution of horizontal mean wind in the lowest 8 metres over a reservoir (1·6 km × 1 km) has been measured using sensitive anemometers freely exposed from a fixed mast in water 16 m deep, the fetch being more than 1 km. The resulting profiles are closely logarithmic, the small differences being systematic and possibly due to the thermal instability which existed when the measurements were made.

The usual law for wind profiles in neutral stability is

where u is the wind speed at height z, k is von Kármán's constant, log z (0) the intercept on the log z axis, and u* the so‐called friction velocity defined by τ0 = pu, τ0 being the surface drag and rH the density of the air.

To characterize the profiles u*/k, their slope, was plotted in relation to z (0), their intercept; this allowed a direct comparison with other profiles, in particular those recently measured in a laboratory channel by Sibul. The agreement was better than expected and indicated that z (0) was comparatively independent of fetch and stability but was largely determined by u*. The relation between u* and z (0) agreed roughly with the simplest non‐dimensional relation between them, gz (0)/u = constant, so that one is led to a generalized wind profile for flow over a water surface

which specifies the drag, given the wind at one known height. An approximate value of the constant is 12·5.

This expression can be compared with earlier work. The better wind‐profile observations show rough agreement; the experimental scatter is necessarily large since a water surface is aerodynamically much smoother than most land surfaces, precision anemometry in difficult circumstances being required to provide sufficiently precise values. Oceanographic measurements of the tilt of water surfaces are in fair agreement at high wind speeds but at low wind speeds the data are conflicting. The early results which imply that the drag‐coefficient (u/u2) increases with decreasing wind speed in light winds are thought to be in error; some support for this belief comes from recent estimates of drag using a modified ageostrophic technique, which agree roughly among themselves and with the general expression.