bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel Two‐Compartment Micelles Formed by Self‐Assembly of Linear Pentablock Copolymers in Selective Solvents
Authors: Liu Dahuan , Zhong Chongli
Published: February 2007

In this work, the formation of two‐compartment micelles from symmetric pentablock copolymers in selective solvents was studied using the dissipative particle dynamics simulation technique, and the effects of block lengths and solvent quality were investigated. The simulations revealed several new morphologies and their formation mechanisms were elucidated at the molecular level, providing useful information that may contribute to the future rational design and synthesis of novel multicompartment micelles with tailored structures.

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Back Cover: Macromol. Rapid Commun. 3/2007
Authors: Liu Jingquan , Bulmus Volga , Barner‐Kowollik Christopher , Stenzel Martina H. , Davis Thomas P.
Published: February 2007

Back Cover: A pyridyl disulfide modified trithiocarbonate RAFT agent was used to directly synthesize end group functionalized amphiphilic block copolymer. The pyridyl disulfide‐terminated copolymer was shown to couple efficiently to a thiol containing model compound without the need for any post‐polymerization modification. Further details can be found in the article by J. Liu, V. Bulmus*, C. Barner‐Kowollik, M. H. Stenzel, and T. P. Davis* on page 305.
Synthesis and properties of BCDA‐based polyimide–clay nanocomposites
Authors: Gopala Krishnan P Santhana , Wisanto Andy Eko , Osiyemi Stephen , Ling Chen
Published: February 2007

Bicyclo[2.2.2]oct‐7‐ene‐2,3,5,6‐tetracarboxylic dianhydride (BCDA)‐based polyimide–clay nanocomposites were prepared from their precursor, namely polyamic acid, by a solution‐casting method. The organoclay was prepared by treating sodium montmorillonite (Kunipia F) clay with dodecyltrimethylammonium bromide at 80 °C. Polyamic acid solutions containing various weight percentages of organoclay were prepared from 4,4′‐(4,4′‐isopropylidenediphenyl‐1,1′‐diyldioxy)‐dianiline and BCDA in N‐methyl‐2‐pyrrolidone containing dispersed particles of organoclay at 20 °C. These solutions were cast on a glass plate using a Doctor's blade and then heated subsequently to obtain nanocomposite films. The nanocomposites were characterized using Fourier transform infrared spectroscopy, differential scanning calorimetry, thermal mechanical analysis, dynamic mechanical analysis, polarizing microscopy, scanning electron microscopy, transmission electron microscopy, wide‐angle X‐ray diffraction (WAXD) and thermogravimetric analysis. The glass transition temperature of the nanocomposites was found to be higher than that of pristine polymer. The coefficient of thermal expansion of the nanocomposites decreased with increasing organoclay content. WAXD studies indicated that the extent of silicate layer separation in the nanocomposite films depended upon the organoclay content. Tensile strength and modulus of the nanocomposite containing 1% organoclay were significantly higher when compared to pristine polymer and other nanocomposites. The thermal stability of the nanocomposites was found to be higher than that of pristine polymer in air and nitrogen atmosphere. Copyright © 2007 Society of Chemical Industry
The population prevalence of children receiving invasive home ventilation in Utah
Authors: Gowans Melissa , Keenan Heather T. , Bratton Susan L.
Published: February 2007

Children requiring home mechanical ventilation (HMV) represent a select group of technology‐dependent patients. We evaluated the prevalence of children using invasive HMV in Utah from 1996 to 2004. Residents of Utah, 16 years old and less ventilated via a tracheostomy between 1996 and 2004 were identified. Children ventilated in 1996 and 2004 were compared. Data including demographic information, diagnosis leading to HMV, and age at initiation were compared between the two groups. The prevalence of HMV in 1996 was 5.0/100,000 (95% CI: 4.4–8.1) and 6.3/100,000 (95% CI: 4.7–8.4) in 2004. Median age at initiation was 6.5 months (IQR: 1.3, 24.0). Sixty‐one percent (n = 47) were male, 84% (n = 65) lived in an urban county, and 86% (n = 66) had public insurance. The most frequent diagnostic category was abnormal ventilatory control (n = 36, 47%), followed by chronic lung disease (n = 19, 25%), airway abnormalities (n = 12, 16%), and neuromuscular weakness (n = 10, 13%). Thirteen patients died (17%). The median length of HMV was 39 months (IQR: 15, 102). Diagnostic categories, age at initiation of HMV, and sex did not differ significantly over the 8 years. The prevalence of children requiring HMV differed very little between 1996 and 2004. Moreover, the diagnoses for which children received this therapy remained constant. Pediatr Pulmonol. 2007; 42:231–236. © 2007 Wiley‐Liss, Inc.
Does sputum eosinophilia predict the response to systemic corticosteroids in children with difficult asthma?
Authors: Lex Christiane , Jenkins Gavin , Wilson Nicola M. , Zacharasiewicz Angela , Erin Ed , Hansel Trevor T. , Bush Andrew , Payne Donald N.R.
Published: February 2007

Little evidence exists to guide the management of children with difficult asthma. The aim of this study was to determine whether children with difficult asthma, associated with sputum eosinophilia, are more likely to benefit from further treatment with high‐dose systemic corticosteroids, compared to those without sputum eosinophilia. Induced sputum was obtained from 20 children aged between 8 and 15 years with difficult asthma before and after a systemic corticosteroid trial (prednisolone 40 mg/day for 14 days or a single 80 mg dose of intramuscular triamcinolone). Subjects were defined as “eosinophilic” if the baseline sputum eosinophil percentage was ≥2.5% or “non‐eosinophilic” if <2.5%. Clinical response to the corticosteroid trial was assessed using spirometry and clinical data and defined by an increase in pre‐bronchodilator forced expiratory volume in 1 sec (FEV1) >9% predicted and/or an overall subjective improvement. Seventeen children had evidence of satisfactory adherence to the systemic corticosteroid treatment; eight of these were “eosinophilic” and nine were “non‐eosinophilic” subjects. Following the trial there was a similar clinical improvement in both groups, with FEV1 increasing in both the “eosinophilic” and “non‐eosinophilic” groups (median change in FEV1 16 [range 5–54]% vs. 12.5 [1–29]% predicted). Sputum eosinophils fell in the “eosinophilic” group (median 17.5 [range 3–37]% vs. 0 [0–23]%, P = 0.054), with no change in the “non‐eosinophilic” group (0 [0–2]% vs. 0 [0–1]%, P = 0.12). Sputum neutrophils did not change in either the “eosinophilic” (22.5 [5–50]% vs. 25 [0–91]%) or the “non‐eosinophilic” group (27.5 [0–96] vs. 44 [9–96]%). In conclusion children with difficult asthma may benefit clinically from high‐dose systemic corticosteroids even in the absence of sputum eosinophilia. Pediatr Pulmonol. 2007; 42:298–303. © 2007 Wiley‐Liss, Inc.
Movement in meteorology
Authors: James R. W. , Douglas C. K. M.
Published: February 2007

It is shown that so far as pure advection is concerned, entities like density, density discontinuity (front) and humidity mixing ratio move with the wind at the level considered. Any disparity between actual movement and streamline movement must be put down to development.

A pressure‐field at a given level is advected in a direction and with a speed given by the average wind at will levels above that level. Similarly the difference in pressure between two fixed levels is advected by the average wind between those levels. Any disparity between actual movement and that determined by the average wind must be attributed to development.

The advection of contours and thickness lines can be inferred from advection of isobars and pressure‐differences in the absence of development.

Winds are normally available up to pressure levels of 60 mb. in the British radiosonde ascents, so that over 90% of the atmosphere can be utilised in computing average winds. There is reason to believe that averages based on this data will be sufficiently accurate to give a satisfactory measure of advection of tropospheric phenomena.

The average wind may also be taken as a measure of frontal advection, in the sence that the frontal through of pressure must be advected in the same way as other pressure fields when development is not of importance.

A measure of upward motion might be obtained on some occasions from a consideration of the conflicting advections at different levels.

The theory of the pressure‐field being advected by the average wind at all levels accounts satisfactory for the fact that systems with “solid” wind currents do not move. An explanation of “thermal steering” is given.
Wind and sea disturbance in the wash
Authors: Champion Donald L.
Published: February 2007

This short note is based on observations of wind and sea disturbance made by the Master of the M.V. Peterborough Trader (102 tons), taken during the months of December, 1939, and January, 1940. The term “sea disturbance” and method of observation is an defined in an earlier paper. A comparison is made between winds blowing off‐shore from the Lincolnshire coast and winds blowing up‐channel from seaward. The effect of fetch and width of channel in the estuary of the River Nene is shown by data for southerly winds.
A micro‐climatological investigation of bath and the surrounding district
Authors: Balchin W. G. V. , Pye Norman
Published: February 2007

The following paper details the organisation and outlines the observations made during the micro‐climatological survey of Bath and district which was undertaken between October 1944 and January 1946 with the aid of a grant from the Leverhulme Research Fellowships and the assistance of numerous voluntary observers. By outlining the methods employed and some of the difficulties encountered it is hoped to assist future research workers in this field and at the same time to provide the necessary background account for subsequent specialist papers dealing with the Bath area. A summary of some of the more interesting facts which have emerged from the investigation is also given.
Note on the dynamics of development
Authors: Sellick N. P.
Published: February 2007

The convergence necessary to produce the appropriate wind field in a deepening depression is compared with the divergence necessary to produce the hydrostatic fall of pressure and it is shown that the latter is comparatively insignificant. The inward and outward movement of air associated with the adjustment of wind to gradient is considerable and it is suggested that accurate streamline analysis of the winds might lead to the detection of areas in which development is taking place.
The effect of the sudan monsoon low on the development of thundery conditions in Egpyt, Palestine and Syria
Authors: El‐Fandy M. G.
Published: February 2007

The thundery conditions which often develop in Egypt, Palestine and Syria, during the autumn, have been further investigated. They have been found to occur when the Sudan monsoon low intensifies towards the north and supplies the eastern Mediterranean with a warm south‐easterly current.

In a great many cases, shallow depressions form over the southeastern Mediterranean, or the adjacent land areas, as a result of the meeting of the above current with the relatively cold northeasterly air of anti‐cyclonic distribution in Asia Minor. In a few cases they form over the western Desert in a manner resembling the formation of khamsin depressions. After being fully developed, these depressions move eastwards or north‐eastwards, while the inflow of the cold air in the rear gives thundery showers. Such thunderstorms are specially marked over the sea, Palestine and Syria.

Over Egypt, however, high‐level instability frequently exists between the warm current and the cool air advancing above. Owing to the stability of the surface layers, this high‐level instability cannot pass into the thunderstorm stage without sufficient convergence of damp air. With a high degree of latent instability severe thunderstorms are then produced.
Natural ice‐particle nuclei
Authors: Palmer H. P.
Published: February 2007

Determinations of the temperature for the first formation of ice in a small cloud chamber at different levels in the free atmosphere are described. The construction in the laboratory of a cloud chamber in which five litres of air can be examined for ice‐forming nuclei is reported. An estimate is made of the concentration of nuclei required, if each raindrop observed at the surface originates as an ice‐particle, to form the rainfall from depressions and from thunderstorms, and it is suggested that the nuclei active in natural cloud are those present in concentrations of 20/litre or less, which can only be detected in a large cloud chamber. Finally estimates are made of the threshold temperatures for the concentrations of these nuclei in surface air, required to form these two types of rain.
Notes on the measurement and estimation of atmospheric radiation –2
Authors: Robinson G. D.
Published: February 2007

An account is given of further measurements of atmospheric radiation which confirm former conclusions regarding the errors of two types of radiation chart when used to compute total radiation at the surface. The greater part of the difference between computed and observed radiation is attributed to two causes – emission from particulate matter and the variation of emissivity of water vapour with temperature. The results suggest a form for this variation between −5°C and +25°C.

Some measurements and computation of the change of radiative flux in the lowest metre at night, i.e., of the direct radiative cooling of the air, are reported. Miscellaneous subjects discussed include the radiation from atmospheric dust, the radiative temperature of a short grass surface and its measurement by simple means in all conditions, and an anomalous occasion with very high incoming radiation for which no explanation could be found. Some comments are offered on the experimental justification of two possible uses of the radiation charts.
The bright band — a phenomenon associated with radar echoes from falling rain
Authors: Hooper J. E. N. , Kippax A. A.
Published: February 2007

Frontal rain when illuminated by radar transmission gives rise to echoes which exhibit a characteristic layer of greater intensity near to the freezing level. Observations which establish the height of this layer or “bright band,” relative to that of the freezing level, are described. Measurements of the terminal velocities of snowflakes of known mass, a factor of importance in support of a possible explanation of the phenomenon, are also given.
The theory and use of upper air thickness patterns in forecasting
Authors: Sutcliffe R. C. , Forsdyke A. G.
Published: February 2007

The combination of the ordinary synoptic chart with the 1,000—500 mb thickness pattern, and the implied 500 mb contour chart, provides a first approximation to a three‐dimensional representation of the troposphere. Although incomplete, the representation permits the introduction of dynamical and thermodynamical theory and provides a basis for scientific forecasting. The forecasting of thickness patterns, in effect of the temperature field, is a thermodynamical problem. The theory of advective, adiabatic and non‐adiabatic temperature change is discussed. A useful approximation to advection is obtained by regarding the thickness lines as material lines embedded in the surface geostrophic wind field. Climatological monthly means and extremes of thickness are given; these provide a practical framework to the forecast. The dynamical development is related with the geometry of the thickness patterns as indicating the vertical variation of vorticity transport. Attention is directed to the development field associated with thermal troughs and ridges, confluence and difluence, and certain combinations of these. When the dynamical development so produced sets up a circulation which by advection maintains or increases the thermal distortion in the same sense, the situation is self‐maintaining or self‐developing. The warm sector depression, the baroclinic anticyclone and the jet stream complex are examples of such systems. A step‐by‐step procedure of forecasting prebaratic and pre‐thickness charts, which has been used in experimental four‐day forecasts, is outlined.
Some further considerations of the measurement and indirect evaluation of natural evaporation
Authors: Pasquill F.
Published: February 2007

A previous observational study (Pasquill 1949 a) has been supplemented by further measurements of evaporation and the associated vertical profiles of wind velocity and vapour pressure in the first two metres above a clayland pasture with grass of moderate length, mainly in effectively adiabatic conditions of flow. The evaporation measurements, using a simple form of soil evaporimeter, included two series of statistically designed measurements, in order further to examine the “reliability” of the technique. The data so obtained, though not comprehensive, indicate no substantial error due to the necessary isolation of test soil from underlying layers, but there is a suggestion that the rates of evaporation ultimately adopted might be underestimates, owing to unavoidable disturbance of root and soil continuity in the vertical at the perimeters of the soil cores contained in the evaporimeters.

The observed rates of evaporation (Eo) are compared with those computed (Ec) from the following formula, which is based on the Prandtl form of the law relating drag and wind profile over a rough surface in adiabatic conditions, Ec = ρk2 (u2–u1) (q1–q2)/[log (z2–d/z1–d)]2 where u1, u2, q1, q2 are the wind velocities and specific humidities at heights z1, z1 above the soil surface, d is a‘zero point displacement’ associated with the vegetation cover, ρ is air density and k is von Kàrmàn's constant, of magnitude 0.4. For the present measurements the usual “roughness parameter,” deduced from the wind profiles, was 0.51 cm as compared with 0.25 cm for the previous series. The two series include 19 separate determinations of rate of evaporation over periods of about one hour, and in terms of different sections of the observed profiles, provide 41 values of Ec/Eo in effectively adiabatic conditions, with wind velocities at a height of 2 m ranging from 3 to 9 m/sec. The mean values of Ec/Eo is 0.99 and the individual deviations from 10 are within 10, 20 and 30 per cent in 24, 66 and 90 per cent of cases. It is demonstrated that deviations of this order are to be expected from local variations in the various factors involved.

Although some a priori uncertainty remains concerning the precise validity of the evaporation measurements, the consistency so demonstrated in terms of a semi‐theoretical treatment which has been established in other connections (Calder 1949) suggests that the ultimate result may be accepted with confidence. Brief consideration is then given to the validity and practicability of applying the above formula to evaporation from areas of growing crops.
The modification of continental polar air over Hudson Bay
Authors: Burbidge F. E.
Published: February 2007

Changes in the physical properties of continental polar air are studied for air currents with trajectories over the Hudson Bay region. Computations indicate that westerly air streams crossing Hudson Bay in early winter are modified to a depth of 5 to 10 thousand ft. By midwinter, however, the modification is found to be negligible. This lack of modification in midwinter is attributed to the formation of an ice surface on Hudson Bay. Changes in the climate of the surrounding area caused by the formation of ice on Hudson Bay are illustrated by changes in temperature, cloud and snowfall. The modifying influence of the Bay in cooling the air in summer and heating the air in early winter is also discussed.
The evaluation of vertical velocity and thickness tendency from Sutcliffe's theory
Authors: Bushby F. H.
Published: February 2007

The field of mean vertical velocity in the 1,000–500 mb layer of the atmosphere due to large‐scale atmospheric systems is computed for six synoptic situations. The method is based on the Sutcliffe ‘development’ theory and an atmospheric model is used in which the isobaric divergence of the velocity field is taken to be a linear function of pressure passing through a level of non‐divergence in mid‐troposphere. The effect of vertical stability on vertical velocity is examined.

The components of thickness tendency due to the computed vertical velocity are evaluated and compared with the differences between the observed thickness changes and their advective components. Some reference is made to the relationship between vertical velocity and rate of rainfall.

General results apparent from the six situations examined are stated and one situation is described in detail. It is concluded that in middle latitudes the difference in vertical velocity between an ordinary stable and a neutral atmosphere may frequently be fourfold and that the component of thickness tendency evaluated from the computed vertical velocity gives a reasonable estimate of the effect of vertical motion on changes in thickness.
The initiation of cyclonic circulation in a vertically unstable stagnant air mass
Authors: Haque S. M. A.
Published: February 2007

Equations of motion are derived in cylindrical co‐ordinates and they are applied to investigate the perturbations in a vertically unstable stagnant air mass having infinite lateral extent and confined between two horizontal planes. A complete solution of the perturbation equation with the boundary conditions is derived. The boundary conditions are then varied by surrounding and surmounting the unstable air mass by stable air. It is shown that the horizontal extent of the unstable air mass has a definite upper limit which depends on the magnitude of instability, height of the disturbance, and the Coriolis parameter.

The mathematical analysis is then applied to show that a tropical cyclone may originate from vertical instability. It is shown by a numerical illustration that the distribution and order of magnitude of the different meteorological elements are the same in the mathematical model as observed in the initial stages of a tropical cyclone.
The mean temperature of central England, 1698–1952
Authors: Manley Gordon
Published: February 2007

A table of monthly mean temperatures representative of the English Midlands has been constructed for the period 1698–1952. From 1815 it is derived from the average of the ‘Radcliffe’ (Oxford) and ‘Lancashire’ monthly means. From 1771–1815 it has been built up by averaging the departures, or anomalies, for each month at a number of inland stations whose records are long enough to be bridged into the years 1815–1840; from 1771–1798 the values thus obtained are reinforced by direct values based on the long Midland record at Lyndon. Before 1771 the existing Edinburgh, Greenwich and Lancashire means are supplemented by further direct values based on Lyndon and Exeter. For all years previous to 1752 the Old Style calendar months have been rectified to the New Style, and the direct values derived from early MS. journals in London, Plymouth, and the Midlands have been carefully collated back to 1728, and extended by means of other short records from Halifax, London and elsewhere back to November 1722. Finally, a direct reduction of Derham's Upminster record, 1699–1706, has been used as a basis for the earliest years. For the intervening years estimates are provided from a consideration of the Utrecht reductions, supplemented for 1713–1722 by non‐instrumental observations of wind and weather in England. Some corroboration of the values so obtained during the eighteenth century is provided; it is hoped that the table can serve as a general standard for studies of English temperature variations until such time as something better can be provided.
Climatic fluctuation in the Greenland and Norwegian Seas
Authors: Brown P. R.
Published: February 2007

Decadal means of air and sea temperature for the year, the month of July and for the season December to March were computed from ships' observations for the sea areas between 60°N. and 70°N. between Greenland and Norway. The climatic fluctuations in different parts of the area are compared.
The dynamical influence of large‐scale heat sources and sinks on the quasi‐stationary mean motions of the atmosphere
Authors: Smagorinsky J.
Published: February 2007

The classical convective theory for the influence of large‐scale zonally asymmetric heating and cooling on the quasi‐stationary mean motions is re‐examined and shown to be inconsistent with observation. Scale considerations indicate that the classical mechanism cannot be applied to heating on a scale larger than that responsible for sea‐breezes. In analogy with the theory of orographically produced stationary disturbances, heat sources and sinks of planetary dimensions produce quasi‐static and quasi‐geostrophic perturbations. A thermally active model is constructed in which all motions except those of large scale are filtered out a priori. The small perturbations produced by an idealized large‐scale distribution of heat sources and sinks acting on a horizontally uniform baroclinic zonal current confined between rigid horizontal planes are then studied. The influence of surface friction is taken into account. Calculations are also performed on a model with no friction and on the assumption that entropy is advected horizontally. The results generally show good agreement with those for the more general model. When the stratosphere is taken into account, the disturbances in the upper troposphere are reduced in magnitude. The conditions for resonance in the absence of friction are determined. The passage through the resonant state is shown to modify significantly the character of the motions. The observed normals are discussed at some length in light of the theoretical computations. It is found that the magnitude and spatial distribution of the model disturbances display substantial correspondence with observation when allowance is made for orographic effects. Finally a method is suggested for quantitatively deducing the three‐dimensional field of non‐adiabatic heating and cooling from the observed normal maps by dynamical considerations.
Turbulence in the upper air, as shown by radar‐wind and radiosonde measurements
Authors: Scrase F. J.
Published: February 2007

Observations of the fluctuations, minute by minute, of wind components and temperature in a radiosonde and radar‐wind ascent up to 30 km were analysed. After allowing for the effects of random errors a standard deviation of about 4 kt for the eddy velocity, with a mean wind of about 25 kt, was obtained. The standard deviation of the temperature fluctuations was 0.85.F in the troposphere but decreased to about one‐third of this in the upper stratosphere.
Properties of spectra of atmospheric turbulence at 100 metres
Authors: Panofsky Hans A. , McCormick Robert A.
Published: February 2007

The properties of spectra of vertical and horizontal turbulence and of their cross‐spectra, at elevations near 100m, are summarized; a few spectra from lower levels are considered. The following tentative conclusions are drawn:

At frequencies of the order of 100c/hr and above, the spectral intensity is proportional to the square of the mean wind speed and essentially independent of the radiation intensity. At lower frequencies, the ratio of spectral intensity to the square of the wind speed increases with increasing incoming radiation.

The intensity‐ratio of the co‐spectrum of vertical and horizontal velocity to the spectrum of vertical velocity increases with increasing wind shear. It also decreases with increasing frequency, n, approximately as n−1.

At low frequencies, the spectral intensity of the horizontal velocity components is generally much large than that of the vertical velocity. At high frequencies, the spectral intensities of all velocity components are of the same order of magnitude. At low frequencies, the ratio of vertical to horizontal spectral density increases with increasing radiation.

The quadrature spectra at a given frequency tend to be negative with large radiation, positive with little radiation. This indicates that edies are low and wide with little radiation, and tall with much radiation.

The frequency at the maximum of the vertical velocity spectrum decreases with increasing height and increasing radiation intensity.

The ratio of tubulent to mean energy is somewhat larger for air with over‐land trajectories than for air with oceanic trajectories.
Soil temperatures in an afforested area in Aberdeenshire
Authors: Coutts J. R. H.
Published: February 2007

Continuous records have been maintained since January 1952 of soil temperatures in a forestry plantation near Ballater, Aberdeenshire. The data have led to the following conclusions:

The mean annual temperatures are practically the same throughout the soil profile.

Inversions of the temperature profile occur in April and August.

The frost‐free periods have been June to September in the air and May to October in the soil at a depth of 1 in. Frosting at a depth of 6 in. has been restricted to the months of December and January, and no frost temperatures have been recorded at depths of 12 in. or more.

During the two years 1952 and 1953 temperatures of 0°C or less have been noted on 167 days in the air, 109 days at a depth of 1 in., and 12 days at a depth of 6 in.

There is severe damping of temperature amplitudes with increasing depth, the diurnal variations being very small at depths exceeding 12 in. Estimates of thermal diffusivities have been made for the soil strata from ground level to 1 in. and from 1 in. to 6 in.

It is found that good estimates of weekly mean temperatures can be obtained from readings of the daily maximum and minimum temperatures.
Continuous convection from an isolated source of heat
Authors: Priestley C. H. B. , Ball F. K.
Published: February 2007

Laws are derived for the variation of vertical velocity, w, and temperature, θ, with height, z, above a continuous circular source of heat of finite extent, on the assumptions that the lateral profiles are of similar shape at different distances above the source and that the resistance is a quadratic function of w. The lateral profiles are then taken to be Gaussian, though not all the properties deduced are dependent on this assumption. Complete solutions are obtained allowing for the thermal stratification of the environment; unless this stratification is neutral the common assumption that the vertical heat flux is constant with height is no longer true.

It is shown that the width of the column will increase uniformly with height. In general w increases with z at low elevations and then decreases, but this second stage does not occur when the environmental lapse rate is large and the source area sufficiently extensive. Under superadiabatic conditions the second stage, when it occurs, is followed by a third stage in which w increases again without limit; under subadiabatic conditions w decreases rather abruptly to zero at a certain ‘ceiling’ height, for which a simple approximate formula is derived.

Numerical values illustrate the application of the solutions to problems of atmospheric pollution, frost prevention, and dry thermals. The solution for neutral conditions is compared with Railston's laboratory measurements.
The general circulation of the atmosphere: A numerical experiment
Authors: Phillips Norman A.
Published: February 2007

A long‐period numerical forecast is made with a two‐level quasi‐geostrophic model, starting with an atmosphere in relative rest. Both friction and non‐adiabatic effects are included in the equations, the latter as a linear function of latitude. Principal empirical elements in the experiment are the intensity of the heating, the value of the vertical stability, and the type of frictional dissipation. The flow patterns which develop are quite realistic, including a jet and zonal surface westerlies in middle latitudes, and the growth of a large disturbance. The associated energy transformations are investigated, and demonstrate the important role of the disturbance in the development of the zonal currents. The meridional circulation is also studied, together with its contribution to the zonal momentum budgets of the lower and upper halves of the atmosphere. Truncation errors eventually put an end to the forecast by producing a large fictitious increase in energy.
Dew
Authors: Monteith J. L.
Published: February 2007

Dew formation on short grass has been studied with a balance, recording weight of condensation, and with filter papers to absorb moisture. Three regimes are distinguished: in the first, daytime evaporation continues and the grass remains dry; in the second, the surface continues to lose weight but the grass becomes wet owing to the partial condensation of water vapour evaporating from the soil; in the third, this loss of weight ceases or there is an increase in weight attributed to condensation of atmospheric water vapour. A distinction is therefore made between ‘distillation’ of water vapour from soil to grass (1–2 mg cm−2hr−1) occurring on very calm nights through a laminar layer with a transfer coefficient approaching the molecular value; and ‘dewfall,’ the turbulent transfer of water vapour from the atmosphere, negligible when the wind at 2 m falls below 0.5 m/sec but reaching 3–4 mg cm−2hr−1 with stronger winds. This distinction is supported by analysis of the surface heat‐budget. On windless nights, since heat flux from the soil and net radiative loss were almost equal, the transfers of sensible and latent heat from the atmosphere were negligible and distillation was of much greater importance than dewfall. Implications for taller crops and warmer climates are briefly considered.
The empirical relation between solar radiation and hours of sunshine
Authors: Glover J. , McCulloch J. S. G.
Published: February 2007

The variation with latitude of the regression parameters a and b in the conventional equation of Ångström type

between total solar radiation on a horizontal surface (Q) and hours of bright sunshine (n) has been examined. It has been shown that the slope of the relationship b is effectively constant, while the threshold value a is a function of latitude. An empirical relationship leading to the Ångström equation at each latitude ϕ over the range 0° ‐ 60° is derived and is shown to give values in reasonable accord with previous experience. It is
On the grid length to be adopted in numerical weather prediction
Authors: Knighting E.
Published: February 2007

The predictive equations of numerical forecasting are cast in differential form and do not have simple analytic solutions. In practice, the finite‐difference analogues of the differential equations are solved using a grid and the grid length has been chosen so that significant features of the synoptic chart are reasonably defined by values at the grid points of contour height or pressure. The purpose of this note is to enquire into the grid lengths that should be chosen so as to make the best estimate of the derivatives which appear in the equations.
Notes on the wind flow at 50 mb in tropical and sub‐tropical regions in January 1957 and January 1958
Authors: Ebdon R. A.
Published: February 2007

In January 1957 the mean 50 mb flow pattern was persistently E'ly over large areas near the Equator and this is compared with the flow pattern of January 1958 which was predominantly W'ly over much the same area. The mean vector winds for Canton Island for six Januarys show a remarkable 2‐yr periodicity and suggest that either an E'ly or W'ly flow is equally likely to occur.
Ice‐nucleating properties of clay minerals and stony meteorites
Authors: Mason B. J.
Published: February 2007

The ice‐nucleating properties of clay minerals have been investigated in relation to their crystalline and surface structures. The kaolin minerals, the illites and halloysite are the most effective and important, their threshold temperatures for ice nucleation lying between −9°Cand −12°C. Minerals of the montmorillonite group and related forms are active only below −15°C. The relative contributions which the various clay minerals are likely to make to the ice‐nucleus content of the atmosphere are discussed in relation to their natural abundance, wind‐borne dispersion and particle size. Kaolinite is considered to be the most important source of highly efficient nuclei in confirmation of results obtained earlier by Mason and Maybank (1958).

Tests on three new specimens of stony meteorites showed them to be inactive at −17°C.
Climatic change through geological time in the light of the palaeomagnetic evidence for polar wandering and continental drift
Authors: Runcorn S. K.
Published: February 2007

The key to the understanding of the gross changes of climate throughout geological time indicated by the geological record in the various continents depends on finding a physical method of determining latitudes in the geological past. The palaeomagnetic method seems to be the most hopeful, but for this one must assume that the average geomagnetic field is a dipole along the axis of rotation. The palaeomagnetic evidence shows this to be true for late Tertiary times – the poles derived from the mean palaeomagnetic directions of Tertiary rocks cluster about the present geographical pole and are distinctly different from the present position of the magnetic pole. There are strong theoretical grounds for believing that it has been true throughout the earth's history. The theory of the irregular fluctuations in the length of the day indicates that the rotation of the core and mantle are only weakly coupled. The electro‐magnetic torque to which this coupling is ascribed is variable because of the short term changes in the geomagnetic field. These fluctuations appear to accumulate with time and so there is always a small differential angular velocity between core and mantle, probably of either sign. Therefore, to an observer fixed on the earth's crust, the earth's magnetic field is axisymmetrical when averaged over periods of the order of the secular variation, i.e., extremely small times geologically speaking.

The palaeomagnetic surveys of the various continents show systematic differences which, it appears, cannot be explained even by assuming that the earth's magnetic field was non‐dipolar, though axial, in times earlier than the Tertiary. Continental drift, as well as polar wandering, must therefore be inferred.

There is a prima facie case that the latitudes thus inferred for the various continents from palaeomagnetic observations do agree with the commonly held inferences concerning the past climates of the earth made by geologists from the study of evaporite deposits, red beds, zonation of fossils, and glacial deposits. A new important check has been provided by palaeowind observations. The inference from the palaeomagnetic studies of Europe and North America that these continents were in low latitude between the Devonian and Triassic is consistent with the wind directions inferred from dune sandstones in Britain and the western United States. The consistency of the directions in the western United States over large distances seems to show that the winds were not affected by local geography.

It appears that an explanation of Continental drift involves the hypothesis of convection currents in the earth's mantle which requires that the mantle is fluid when subjected to small stresses existing for many millions of years.
Short‐wave reflection coefficient for a field of maize
Authors: Graham W. G. , King K. M.
Published: February 2007

Hourly and daily determinations of the reflection coefficient for a field of maize (Zea mays) were made on 17 days from July to September 1958. An Eppley pyrheliometer was used to measure incident solar radiation and a Kipp solarimeter was used to measure reflected radiation. The hourly determinations showed increased reflection at low solar altitudes. With a moist soil, the reflection coefficient based on the daily radiation was 0·12 to 0·15 when the plants were small and 0·17 to 0·19 when the crop was fully developed. When the soil surface was dry and the plants small, the coefficient was 0·21. Tassel formation and freezing of the plants had no effect on reflection.
Large‐sphere limit of the radar back‐scattering coefficient
Authors: McDonald J. E.
Published: February 2007

In the limit of large scatterer diameters, the Mie theory must converge to geometrical optics. Previous results of Mie‐theory calculations of the radar back‐scattering coefficient σb have suggested that its large‐sphere limit is the ordinary reflection coefficient R of the scattering material. A proof that this is the asymptotic value of σb is given.
The use of smoothing or filtering operators in numerical forecasting
Authors: Wallington C. E.
Published: February 2007

With the view to improving numerical forecasts by damping the growth of spurious waves, particularly those with short wavelengths, smoothing operators have been applied to thickness and contour fields at intervals during the forecasting computations. There appears to be no simple objective method of determining sets of smoothing coefficients for the optimum improvement of a particular model, but preliminary attempts to smooth and improve numerical forecasts at Dunstable have been made on a trial and error basis. The results show the smoothing or filtering technique to be a powerful method of empirically improving numerical forecasts.
The electrification of frost deposits
Authors: Latham J.
Published: February 2007

Experiments showed that the exposure of a frost deposit to an air‐stream caused ice splinters to be blown away from the deposit. These splinters were negatively charged if the air‐stream were warmer than the deposit, and positively charged if it were colder; if they were at the same temperature then no electrification was produced. In a typical experiment, with the frost deposit 10$C warmer than the air‐stream, the average charge carried away on a frost splinter was 6 × 10−7 e.s.u. These results can be explained, in sign and magnitude, by the Latham‐Mason theory of charge transfer associated with temperature gradients in ice; in the frost‐electrification experiments a temperature gradient was produced down a frost needle owing to the difference in temperature between the air‐stream and the frost deposit, thus causing the outer and inner tips of the needle to acquire equal and opposite charges. If the needle were then broken and blown off by the air‐stream it would carry away a charge of one sign leaving that of the other sign on the frost deposit on which it had grown; the sign of the observed charging was in agreement with the theory. Putting into the temperature‐gradient equations measured values of the dimensions of an ice splinter and the temperature difference between its ends it was possible to calculate the theoretical charge residing on the ends of an ice splinter; this value was found to be in good agreement with the measured average charge per splinter.
Measurement of horizontal convergence in precipitation using a Doppler radar ‐ a case study
Authors: Harrold T. W.
Published: February 2007

A method of measuring convergence in precipitation using a Doppler radar is described. A case study illustrates the results obtainable. The presence of a ‘wind front’ (sloping shear zone), which could not be related to any feature on the synoptic scale, was revealed (Fig. 6). Layers of convergence and divergence, particularly in association with a frontal inversion, were identified (Fig. 7). Convergence below the front was largely compensated by a pronounced divergence (D ∼ 50 × 10−5 sec−1) immediately above the front. The computed vertical velocities (Fig. 9) showed ascent of the order of 10−2 mb sec−1 during the rain.

Although measurements were made over an area of less than 300 km2, the evidence suggests that the variations of convergence were not purely local, but were a consequence of an organized dynamical system on a scale comparable with other features of fronts.
Lidar: A new atmospheric probe
Authors: Collis R. T. H.
Published: February 2007

Pulsed‐light techniques of probing the atmosphere have been greatly extended by employing lasers as energy sources in instruments called ‘lidars.’ Because of the nature of laser energy and the manner in which it is used in current and proposed systems, lidar is best discussed in terms of radar. Apart from the basic capabilities of lidar for detecting backscattering from atmospheric constituents, possibilities exist for more sophisticated techniques based on the wave nature of the energy. The basic capabilities of lidar, however, make it possible to observe the atmosphere with previously unknown resolution and sensitivity. Apart from providing new information about clouds, lidar has shown that the concentration of the particulate matter content of clear air is highly variable and that such variations can indicate the structure and motion of the clear atmosphere. These capabilities have applications in atmospheric and meteorological research and various operational activities.
An experimental study of wind‐generated waves on a water current
Authors: Francis J. R. D. , Dudgeon C. R.
Published: February 2007

In a laboratory wind tunnel, air was circulated above water which itself was moved by a pump. The resultant waves were measured photographically at fetches less than 7·3 m, and crudely averaged. With opposing water currents, both wave heights and wave lengths were larger than those produced with the same relative wind speed but with no water current: with an assisting water current, wave heights and lengths were both smaller. The waves were of the same steepness ratio for all wind speeds, and were breaking.
Mean meridional circulations in the Northern Hemisphere lower stratosphere during 1964 and 1965
Authors: Vincent D. G.
Published: February 2007

Zonally‐averaged mean monthly circulations in the meridional plane, which have been forced from momentum and heat sources, are presented for the 100–50 mb, 50–30 mb and 30–10 mb pressure layers, between 25°N latitude and 80°N latitude, during 1964 and 1965. The zonal momentum and continuity equations, written in spherical coordinates, are combined, using an iteration process, to compute mean meridional and vertical motions.

Fixed boundary values are required for the vertical component at 10 mb where the downward vertical integration starts and for both components at 22·5°N and 82·5°N latitudes. These values are computed from the initial guess fields, which are based on approximate thermodynamic balance for the vertical component and a momentum balance for the meridional component. The effects of these boundary conditions on the interior motions are discussed.

The results of the computed velocity components show a reasonable and consistent pattern, both in time and space. In winter months, motions are much more intense than in summer months and the flow patterns are characterized by cell‐like structures, having upward motions over the pole and downward motions over middle latitudes. It appears as though the lower stratospheric motions over mid‐latitudes are an extension of the tropospheric indirect mean cell. There is a poleward shift in the motions as winter progresses into spring and an equatorward shift as autumn progresses into winter. In summer, the motions are small and not too well organized.

In the January and July 1964 momentum budgets, it is shown that a near balance exists between the Coriolis torque and the convergence of eddy momentum flux, which gives an approximate expression for calculating mean meridional velocities. In the January 1964 heat budget, at middle latitudes, a near balance is shown between adiabatic subsidence and heat sources due to radiation and eddy heat‐flux convergence. This balance implies an approximate solution for mean vertical motions. However, this approximation does not appear to be valid near the latitudinal boundaries during January or in certain regions during July.