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Nucleation events involving water and ice play a vital role in many atmospheric processes. This paper describes a molecular model for prenucleation water clusters. Results are presented for the formation of these clusters from the supersaturated vapor. The temperature dependence of the model is shown to agree with the classical (liquid drop) model and nucleation rates are calculated and compared with experiment. This model has the advantage of being readily extended to homogeneous and heterogeneous nucleation of ice as well as being applicable to the description of ion-hydration processes. We believe the information inherent in the model concerning interactions on a molecular level can be applied to nucleation phenomena in the atmosphere and can enhance understanding of these processes. This introductory paper describes the progress which has been made and the areas of extended application of these results.

This paper is concerned with the effects of nonlinear eddy coefficients on rising, dry fine thermals. The base atmosphere in which these thermals are embedded is hydrostatic, horizontally homogeneous, nearly neutral, and without an ambient wind. By identifying the turbulent transfer terms with the subgrid–scale motions, a nonlinear formulation, based upon the worn. of Lilly and Smagorinsky, is obtained for the eddy coefficients. The mixing length in these terms is based upon a vorticity formulation rather than the size of the numerical grid used in the computations. Using numerical techniques based upon the work of Arakawa, and Adams and Bashforth, we tested these formulations by following the evolution of rising line thermals. We concluded that the eddy formulation used in this paper is more realistic than using constant coefficients throughout the field of computation. In addition, we found that the density stratification is important if the convective layer is deeper than 3 km.

This paper discusses the likely differences between the diffusion of gaseous and particulate matter in the atmosphere, as would be observed by fixed point instruments (“absolute” diffusion). The potential complicating factor of an “inertia effect” (which would cause a heavy particle not to participate in the higher-frequency oscillations of its fluid-particle neighborhood) is shown to be negligible in the atmosphere. Two interrelated effects termed here the “effect of crossing trajectories” and the “continuity effect,” could be, on the other hand, of great practical importance. Both are caused by the relatively rapid travel of heavy particles across the atmospheric eddies and both could result in an appreciable reduction of dispersion rates. Some estimates of the likely magnitude of these effects are given in the paper.

“This report was prepared in 1916, but on account of the war it was not then published.” The subject is discussed under the following headings: Methods and places of observation. Amount and reliability of the material. Mean temperatures and gradients. The seasonal variation. The daily temperature range. The humidity. The troposphere and stratosphere. Pressure and density. The motion of the free atmosphere. Statistical data. The connection between pressure and temperature. The vertical temperature gradient and the value of Hc. Appendix. The standard deviations of the density of the air from 1 to 13 kilometers. and the frequency of occurrence of deviations of given magnitude. In general the paper deals with data and conclusions that had already been presented elsewhere, but they are here brought together into concise form, together with some of the more recent results. The readers thus enabled to gain a comprehensive idea of the whole subject without having to consult several separate papers that h...

This paper describes the first step in the development of another global climatic model in which the structure of the atmosphere and consequently its optical properties are dynamically coupled to the surface temperature. Rather than considering clouds as discrete entities, we structure the atmosphere as a diffuse thin cloud by utilizing the fundamental thermodynamics of the cooling of moist air of fixed surface relative humidity maintaining vertical mechanical equilibrium. Vertical convective thermal mixing is parameterized as is the amount of condensate that is “rained” out. The remaining condensate is distributed as spherical droplets by an assumed distribution function. The modified two-stream approximation employing a Gaussian quadrature is used to solve the radiative transfer equation. The reflectivity and transmissivity of the model atmosphere and a given amount of aerosol are then calculated. These quantities, together with a parameterization of surface reflectivity to surface temperature,...

This paper describes a parameterization of convection developed for use with a multi-level primitive equation model of the atmosphere. This parameterization is similar in form to that of Kuo, who postulates that boundary layer air rises moist adiabatically before mixing with the large-scale flow. A major difference from Kuo arises, however, when we allow condensate (the cloud material) to be evaporated to the large-scale flow during the mixing process. This parameterization conserves moisture and energy of the large-scale flow in a fashion similar to Manabe, and is suitable for general circulation studies as well as short-term prediction. The parameterization tends to adjust the vertical profile of temperature to the pseudo-adiabatic lapse rate from the boundary layer, and the relative humidity tends to saturation. Adjustments are made frequently to points in the tropics. Results are compared with a similar integration using Manabe's convective adjustment scheme. The parameterization presented ma...

Information regarding small-scale turbulence in the Venus atmosphere is important and desirable because it contributes to understanding of the atmosphere's circulation. It is demonstrated that the radio occultation data of a flyby spacecraft such as Mariner 5 can provide valuable information on turbulence in the Venus atmosphere. Unlike previous studies of the Mariner 5 data, this paper is based on the frequency spectrum rather than the variance of the log-amplitude fluctuations. The excellent agreement between the processed and previously derived theoretical spectra furnishes strong evidence that the Mariner 5 fluctuations are primarily turbulence-induced. It is seen that, above 35 km, turbulence is strongest in the vicinity of 45 and 60 km, and that the outer scale of turbulence is of the order of 100 m. Comparison with the results obtained from the Venera missions is also discussed.

Forecasts of the position and structure of the St. Louis pollutant plume became necessary during the NCAR Fate of Atmospheric Pollutants Study (FAPS). The purpose of the project was to obtain estimates of the mean lifetimes of a number of short-lived pollutants by taking measurements at distances of 80 and 120 km from the Gateway Arch. Determining where and when to make such measurements at a reasonable cost involved assessing the interaction of the pollutants from the city with the atmosphere. This paper describes the concepts used by the meteorologist to help anticipate the variation of the plume in space and time, including its diurnal variation, in weather conditions considered favorable for sampling. The plume models that evolved from these concepts are presented, and a comparison is made of the actual behavior of the plume as determined from measured concentrations of the pollutants with the behavior predicted by the models. The comparison shows good agreement.

The nonlinear dynamics of inertial-gravity and Rossby waves are studied via the asymptotic method of multiple scales. Two important parameters which enter the problem are the conventional Rossby number ϵ and a nondimensional measure of the northward variation of the Coriolis parameter μ. Restricted to the weakly nonlinear limit (ϵ≪1), this paper examines three possible nonlinear wave motions: weakly non-linear interactions on an f-plane (μ=0), very weakly interacting disturbances in a quiescent atmosphere [ϵ=O(μ2)], and nonlinear interactions of finite-amplitude disturbances [ϵ=O(μ)]. In particular, resonant interactions are studied and the slow modulations of the linear solutions due to the nonlinearity are found. Some of these nonlinear solutions are unstable, being able to feed their energy into a resonantly interacting pair of disturbances.

Moist air from the tropics moves into northwest Mexico and the southwestern portion of the United States during the early part of the summer season. This is analogous to the monsoon circulation in other sections of the globe. The annual change in circulation has been related to the northward and westward development of the large subtropical high pressure system over the southern United States. With this change the moist tropical air over the Gulf of Mexico is believed to be carried across Mexico and into the southwestern United States. The mountains of Mexico provide a formidable barrier for the movement of the Gulf of Mexico moisture westward. It has been shown that half of the precipitable water vapor in the atmosphere over the Arizona deserts in the summer months is below the 800-mb level. This is inconsistent with the idea of the Gulf of Mexico supplying the greatest proportion of the moisture. This paper presents support for the greatest percentage of tropical moisture in the southwest Unite...

Signals transmitted through the atmosphere in the visible and infrared portions of the electromagnetic spectrum can be seriously degraded by clouds between the source and the receiver. A previously published model was developed for estimating probabilities of cloud-free lines-of-sight through the atmosphere at any desired elevation angle and geographical location. This paper extends the published model to the problem of estimating probabilities of cloud-free lines-of-sight from n of m observing sites. A climatic record of sky-cover observations taken simultaneously from all m sites is required before the model can be applied.

In conjunction with a companion study, this paper discusses the pollutant dispersion as predicted by solving numerically the equations of a transient, one-dimensional transport model. The results show that while the radiative properties of the aerosols have only a slight effect on the daytime pollution concentration; they do lead to decreased instability during the day. The gaseous pollutants, however, play a major role by lifting the elevated stable region thereby reducing pollution buildup. This alteration of an elevated stable region is important since air pollution episodes usually occur when such elevated inversions are present.

This paper is concerned with a preliminary study of the feasibility of determining total atmospheric ozone from satellite measurements of the solar ultraviolet radiation diffusely reflected by the earth's atmosphere. The atmospheric model used is plane-stratified, and the evaluation of the radiation field takes into account all orders of Rayleigh scattering. In addition, the model provides for variations in the total amount and vertical distribution of ozone, as well as the Lambert reflectivity and pressure at the effective base of the atmosphere. The results indicate that the wavelength region in which measurements should be made lies between about 3125 and 3175 A, if the observations are restricted to the nadir direction. Wavelengths shorter than 3125 A do not penetrate adequately through the ozone layer and do not, therefore, contain information on total ozone content. On the other hand, wavelengths much longer than 3175 A although they penetrate the ozone layer, in general offer rather poor s...

In the present paper the production of kinetic energy in the atmosphere is examined from a hydrodynamical point of view. The results indicate that the intensity of the primary source of horizontal kinetic energy at any point in the atmosphere is equal to the pressure multiplied by the horizontal divergence of the velocity. Regions of horizontal velocity convergence appear as hydrodynamical sinks for kinetic energy, in addition to frictional effects. It is found that kinetic energy may be transferred through advection and through work done by pressure forces. It appears that diverging anticyclones are of primary importance in providing kinetic energy for the general circulation.

Increasing indication of interaction between the stratosphere and mesosphere makes it seem probable that effects from the lower atmosphere will not be uncommon among the variations of the earth’s magnetic field especially in the form and range of the daily variation of the field. Meteorology may be able to aid space research by identifying effects in the magnetic records that may be of atmospheric origin in order that they not be mistaken for direct solar effects. Extending the work of two earlier articles this paper gives the daily variation of the horizontal intensity of the earth’s field for San Juan, Puerto Rico, as the quiet-day average for the 11 years 1948-58 in a form which illustrates seasonal features that the author believes arise from prevailing ionospheric winds. Further, semi-monthly individual 5-day averages of the daily variation are given for San Juan for a period of 12 months in 1957-58 for which a description of the stratospheric circulation at roughly 30 km. altitude (10 mb.) was available.

This paper describes the results from a study of winds above and in a pine forest for a continuous period of 22 days. The winds are examined with reference to direction and time of day, that is, the effects of topography and atmospheric stability are considered. At night, when the atmosphere is stable, variations in profile shape above the forest are associated largely with site properties. During the day the variations are less, indicating that convective turbulence tends to control the profile shapes and to mask the effect of site irregularities. An examination of the power law provides tentative agreement with another study as well as with a model study. It is proposed that the ratio of the wind speed in the trunk space to the wind speed above the canopy is a measure of the magnitude of momentum transfer through the canopy. This ratio reaches a maximum at noon. At night the ratio drops to 75% of its daytime maximum value and displays a marked variation with direction.

Mid-tropospheric cyclones are an important part of the tropical general circulation of the summer season. These are synoptic-scale disturbances which appear in the daily and monthly mean circulation maps with greatest intensity at levels near 500 mb. The structure and energetics of this type over southeast Asia are discussed in this paper. Interesting features include a warm anomaly above the cyclone and a cold anomaly below. A five-level non-geostrophic balanced model is used in this study to obtain the distribution of vertical motion. The model includes a parameterization of cumulus-scale convection. In the middle levels, rising motions are found west of the cyclone and sinking motions to the east. This is primarily due to the thermal structure of the atmosphere and associated advection of colder air from the oceanic regions and warmer air from land areas. A marked diurnal change in the vertical velocity is noted in the computations; magnitudes are large at 0700 local time compared to 1900. Thi...

The search for causes of the rising temperatures in some geographic areas during the twentieth century has directed interest toward the amount of atmospheric carbon dioxide (CO2). If the carbon dioxide added by the combustion of fossil fuels remains as a net increase, any temperature-changing effects of its presence as a minor constituent of the atmosphere should be cumulatively operative as the amount increases. In this paper, the physical knowledge of atmospheric CO2 is examined and the available nineteenth and twentieth century observations of the atmospheric CO2 concentration are summarized to ascertain the extent to which they corroborate claims that the amount of atmospheric CO2 has increased since the nineteenth century. In the light of the uncertainty of both physical knowledge and of statistical analysis, it is concluded that the question of a trend in atmospheric CO2 concentration remains an open subject.

This paper presents tables for the computation of the rate of temperature change due to infrared radiation in the free atmosphere. The tables are based on empirical measurements by F. A. Brooks and Robinson of the emissivity of water vapor, and allow the computation of the rate of radiational temperature change at a given level of the atmosphere by a modification of Bruinenberg's equations for the divergence of the net flux. An example is given. Results of the method are compared with those obtained by other methods. A lack of basic evidence on the relationship between emissivity and temperature is noted.

Based mainly on Howard, Burch and Williams' laboratory absorption data for the near infrared H2O and CO2, bands, and on the solar absorption data for the red and near infrared O2 bands, the direct absorption of solar radiation in near infrared atmospheric bands has been estimated. The estimated absorptivities of the H2O bands in the interval from 0.7 to 2.1 μ are in fair agreement with MeDonald's estimates which are based on Fowle's absorption data. However the absorptivities of the H2O bands from 0.7 to 6.3 μ are larger than McDonald's values. CO2 and O2 absorptions become increasingly important in the upper troposphere and in the stratosphere. Average heating (deg C day−1) was also estimated for London's model atmospheres for clear sky conditions, and compared with the similar estimate made by Roach. For the atmosphere above 300 mb the heating estimated in this paper exceeds that estimated by Roach. Conceivable causes of this discrepancy are pointed out.

This paper summarizes certain facts of observation, as reported by a number of investigators, concerning the nature of climatic variations on the earth's surface during observational time, during postglacial or historical time, and during the geological past. Particular emphasis is placed on possible interpretations or explanations of these changes. The discussion of the secular variations of the world weather patterns during observational time stresses on the one hand apparent relationships between these variations and solar activity, as indicated by sunspots, and on the other hand the essential similarity of these secular variations to those which occur from week to week and month to month in the fluctuation of the general-circulation pattern between more zonal (high index) and more cellular (low index) characteristics. The discussion of the variations of world climate during geological time is concerned primarily with the relative merits of the three principal theories which currently attempt ...

This paper describes a model of the general circulation of the earth’s atmosphere which has been developed and experimented with, since 1964, at the National Center for Atmospheric Research (NCAR), Boulder, Colo. A distinguishing feature of the NCAR model is that the vertical coordinate is height rather than pressure, though hydrostatic equilibrium is maintained in the system. In fact, the dynamical framework of the model is very similar to the one proposed by L. F. Richardson in 1922. Various physical processes in the atmosphere, such as energy transfer due to solar and terrestrial radiation, small-scale turbulence and convection, etc., are incorporated in the model. An explicit prediction of the moisture field is avoided. Instead, it is assumed that the atmosphere is completely saturated by water vapor. Thus, the release of latent heat of condensation can be computed. In addition to a description of the model, the equations for the zonal mean and eddy energy are presented. Finally, a baroclinic stability analysis of the model is made in order to gain an insight into the finite-difference formulation of the present model. Long term (over 100 days) numerical integrations are being performed successfully with a two-layer version of the present model. Details of finite-difference schemes and the results of numerical calculations will be described in a separate article. “Perhaps some day in the dim future it will be possible to advance the computations faster than the weather advances and at a cost less than the saving to mankind due to the information gained. But that is a dream.” [From Weather Prediction by Numerical Process by L. F. Richardson, 1922.1

Recent studies have revealed a relationship between variations in gravitational tidal forces and rainfall. A possible mode of interaction of the tidal forces on atmospheric processes is suggested to explain how the tidal forces which are small may induce detectable effects on atmospheric circulation, considering both synoptic-scale and short-period processes in the atmosphere. The variability of gravitational tidal forces is compared with variations in precipitation as revealed by statistical studies. The interrelation between thermal and tidal forces is brought out to account for the anomalous distribution of maximum precipitation in the United States during the synodic month when classified according to seasons, geographical areas, and periods of high versus low solar activity. The model suggested in this paper is based on an intuitional approach to the problem. Its usefulness or validity can be ascertained only by further investigations of rainfall variations; in addition there is the need to ...

This paper first gives a short survey of the modern view of atmospheric electricity. According to this, there exists in the atmosphere an electric-current system which generates from the thunderstorm activity and which is influenced in an essential manner by the resistance of the air and its variations. This electric resistance of the air, its magnitude and its diurnal variation, depend on local conditions, on the season and on the weather situation. For these reasons, the electric resistance of the air is an essential correlator between the meteorological-aerological and the atmospheric-electrical phenomena. Observations of the potential gradient and the air-earth current at the Jungfraujoch in Switzerland (3472 m) during summer and autumn are given as examples. It follows from these observations that: (1) the diurnal variation of the austausch reaches to this altitude during summer (in the free atmosphere only to about 2500 m), (2) during autumn the Alps' ridge becomes free from this effect, an...

The experiment reported in this paper was designed to study the effect of large mountain-barriers on zonal currents in the atmosphere. Obstacles of various sizes and shapes are moved zonally in a rotating spherical shell of liquid, and observations are made of the resulting perturbed flow. Striking differences occur, depending on the direction of relative rotation of the barrier. If the flow is westerly with respect to the obstacle (in the direction of the basic rotation), a strong anticyclonic circulation develops around it and this sets up planetary waves around the globe. The wave number is found to correspond very closely to a frequency equation derived from the vorticity equation. If the flow is easterly relative to the obstacle, a similar anticyclonic circulation arises, but is confined to the immediate vicinity of the barrier. No long waves occur but, if the motion is viewed with respect to the spherical bowls, the obstacle, moving eastward, drags a strong westerly jet with it in its latit...

Since certain constituents (water vapor, ozone, carbon dioxide, etc.) of the atmosphere have pronounced absorption and emission bands in the infrared region of the spectrum, the radiation which is radiated upward from the atmosphere will depend on the distribution and temperature of the constituents, and this radiation can be measured from meteorological satellites. This paper shows sample calculations of the emission by the water vapor in three wavelength intervals (at two places in the strong absorption band, 6.0 and 6.2 µ, and in the region of weak absorption, 8 to 13 µ). Water-vapor distributions used in these calculations are those for the United States, measured by the University of Chicago and showing rather high stratospheric humidities; for the United Kingdom, measured by the Farnboro Research Establishment and showing rather low stratospheric humidities; and for Swan Island, West Indies, where no humidity data were available above about 10 km. It is shown that, for very strong absorptio...

The successful flights of the Venera 4, 5 and 6 probes resulted in direct, in situ measurements of the chemical composition, pressure, temperature and density of the Venus lower atmosphere, and gave rise to a tentative atmospheric model for the planet. These measurements permit a more definite discussion of the mechanisms responsible for the observed characteristics of the thermal conditions on Venus. In this paper, an approximate analysis of heat transfer processes in the Venus atmosphere is made, representing the continuing development of the preliminary study described by Avduevsky et al. Radiative fluxes have been calculated, a model of the convective motions in the lower atmosphere has been evaluated, and the importance of radiative and convective energy transfer in the planet's total heat balance has been estimated.

This paper describes the development of a turbulent boundary layer in a neutral atmosphere downwind of an abrupt change of surface roughness. Both a single change and two subsequent changes are treated. For the treatment of a single abrupt change, a theory of Townsend forms the starting point. It is proved, according to this theory, that no surface layer adapted to the underlying surface roughness can exist behind the change. It is then shown how Townsend's theory can be modified in such a way that this discrepancy is removed. The modified theory gives nearly the same velocity profile as does the original. However, it leads to greatly different values of the surface shear stress behind the change, a matter of importance in calculating turbulent transport. It is shown that a correct evaluation of the height of the adapted layer is of importance for the determination of surface shear stress and roughness height from measured velocity profiles. The modified form of Townsend's theory is then extended...

This paper presents the results of measurements of size distributions of particulate matter in the atmosphere. The general shape of the distributions is discussed, particularly the appearance of maxima corresponding to particles with radii about 6×10−6 cm and the sizeable fraction of the total particle population in the region r≤10−6 cm. Size distributions obtained from the same air mass before and after fog formation show apparent removal of smaller particles (r≤10−6 cm) which is consistent with Smoluchowski's coagulation law. Several representations of size distributions are presented in order to compare the results obtained with those of other researchers.

Estimates of atmospheric heating in the troposphere at Washington, D.C., for each successive 12 hr. during June and July 1961, were used to study the relation between local heating and the large-scale features of the circulation, to determine the local production of available potential energy, and to assist in interpreting cloud and radiation data from meteorological satellites. Some interesting inter-connections are found between heating and the circulation: e.g., it is shown that there is a very critical phase relation between heating and the temperature field which is important in determining the generation or destruction of the atmosphere’s potential energy. This suggests that special care is needed in designing numerical computations of diabatic heating. A major effort should be directed to interpreting satellite data in terms of the atmospheric heat budget, because such global estimates may be useful (using a procedure suggested in this paper) in determining the world-wide distribution of regions of maintenance or destruction of potential energy.

SYNOPSIS This paper summarizes observations with an Owen's dust counter furnished to the Weather Bureau by the Bureau of the Meteorological Section of the International Union of Geodesy and Geophysics, to promote international cooperation in a study of the dust content of the atmosphere. A similar instrument has been furnished to eleven other countries affiliated with the Union. Most of the measurements by the Weather Bureau have been made at the American University, a thinly settled suburb to the northwest of the city of Washington. Some have been made at the central office of the Weather Bureau, and at the base and top of the Washington Monument, within the city. A few have been obtained in other cities, and interesting series have been obtained during airplane flights. A summary of the results shows at the American University an average of about 850 particles per cubic centimeter in winter, and about 400 during the summer months. The extremes vary between about 4,000, on an unusually smoky day...

Studies carried out in Alaska and Canada have shown that fog is a relatively rare phenomenon at temperatures between 0° and − 30°F, with a minimum frequency between − 20° and −30°. At still lower temperatures, however, the frequency of fog increases rapidly. This effect is noted only in the immediate vicinity of inhabited areas, such as towns and airfields. The reason for the sudden increase in fog frequency at these temperatures, and the rarity or lack of fog at the higher temperatures, has not been heretofore explained. In a recent study on aircraft condensation trails, it was shown that if the temperature is sufficiently low (between − 20 and − 40°F, depending on the relative humidity), the burning of hydrocarbon fuels, such as would occur in towns and at airfields, easily results in supersaturation of the air and a “surface contrail” or ice fog. At higher temperatures, on the other hand, combustion actually reduces the relative humidity of the atmosphere, hindering the formation of fog. In this paper it is shown that low-temperature (ice) fogs form as a result of the combustion process, and curves are presented showing the temperature-dew-point relationship necessary for the formation of such fogs.

An attempt is made in this paper to formulate the transport of hydrogen in the earth's upper atmosphere as a Monte Carlo problem. The relevant details of the technique adopted are given. The capability of the technique to provide useful answers to the following questions is demonstrated. How is the flux of hydrogen atoms, possessing enough kinetic energy to escape from the earth's gravitational field, influenced by the fact that the escape takes place not from a particular atmospheric level (the critical level) but from a layer of finite thickness? What is the law of variation of hydrogen density in this finite layer? More specifically, does the hydrogen gas maintain a Maxwellian distribution while diffusing through the layer? If not, how does the distribution change with height inside the layer? The answers obtained are discussed with reference to their statistical validity, and compared with some of the conclusions of earlier investigations.

This paper presents comparisons of experimentally determined radiation temperatures using the black ball, with such temperatures calculated using the Elsasser radiation chart. The comparisons show that, in general, the calculated temperatures are always warmer than those observed, indicating that the earth and its atmosphere radiate less energy away to space than would be calculated. The agreement between observation and calculation appears to be best in summer, when the water-vapor path length is greater at all altitudes, and worst in winter. A description of the approximations which enter into the calculations and a detailed investigation of the validity of these assumptions, obtained by noting experimental results, are also presented. The conclusions are that some of the approximations are experimentally verified only in part and that two of them, the separation of CO2, ozone, and water vapor radiative effects, and the use of a pressure scaling factor on path lengths, are clearly invalidated.

The concept of a geostrophic point vortex results from incorporating the geostrophic approximation in the equations of motion of the one-layer homogeneous atmosphere with a free surface. A consistent, systematic approximation procedure is used, yielding higher-order approximations without requiring additional physical assumptions. Application to the prediction of hurricane tracking and upper-air cyclogenesis is discussed. This paper is based on Report IMM–NYU 226, “On the Theory of Large-Scale Nearly-Horizontal Motions in the Atmosphere” (February 1956) written under the auspices of the Geophysical Research Directorate, U. S. Air Force Cambridge Research Center and the U. S. Office of Naval Research.

SYNOPSIS This paper considers briefly the magnitude of errors in solar constant determinations arising from errors in the fundamental pyrheliometric readings and in their extrapolation to zero atmosphere. The degree of correlation between solar constant determinations made nearly simultaneously at Montezuma, Chile, and Harqua Hala, Ariz., leads to the conclusion that only an insignificant part of their day-to-day variations can be attributed to some such common cause as solar variability.

Many contaminant or smoke-puff experiments have been performed in the atmosphere to determine certain significant parameters of atmospheric turbulence. This paper presents a reanalysis of some of these experiments, using a technique suggested by Frenkiel and Katz. The results show that the similarity theory of Batchelor, as suggested by Gifford, and the, subsequent theory of Lin, explain atmospheric turbulence for the case of low wind shears. Turbulent dispersion in the presence of high wind shears, however, follows the diffusion relation theorized by Tchen. Values for ϵ, the rate of eddy-energy density dissipation per unit mass, are measured, substantiating some of Gifford's estimates; also measured are the universal and absolute constants C1, and α respectively, of Batchelor, and u2 the turbulent energy density per unit mass, which are compared to some measurements of Frenkiel and Katz, and of Kellogg.

This paper describes the results of studies on the effects of the atmosphere on radio astronomy observations at X-band. The fluctuation component of atmospheric noise radiation is shown to be strongly correlated with cyclonic conditions and frontal activity.

This paper describes the method of incorporating into the NCAR global circulation model the dynamic effect of mountains, the prediction of cloudiness for radiation calculations, and the calculation of ground surface temperature using a heat balance equation. Other aspects of the physics of the model and the finite-difference schemes are very similar to those discussed by the authors in 1967 and 1970. For the simulation of seasonal climate we specify two parameters: the sun's declination and the distribution of ocean surface temperatures. Since the prediction of cloudiness is parameterized in terms of the relative humidity and the vertical motion fields, solar and atmospheric radiation processes interact closely with the dynamics of the atmosphere through variations in the fields of cloudiness, temperature and water vapor. Coupling between radiation and dynamics helps to maintain stronger baroclinic activity in middle latitudes. Although a hydrologic cycle is included in the model atmosphere and t...

Recent experiences with tropical meteorology around the world have brought to light the frequent existence of a zonal band of west winds in the vicinity of the equator, which appears not to be associated with the westerlies of middle latitudes, but which rather seems to be found between the trades of the two hemispheres. The boundaries of the equatorial westerlies are usually characterized by increased cloudiness and poor weather. In this paper an attempt is made to prove that the westerlies of equatorial regions are not simply transitory phenomena but instead should be considered as an integral part of the normal general circulation of the atmosphere. Seasonal variation of the latitude of maximum insolation is the factor introduced to explain the existence of the west winds. A second explanatory theory is discussed in which radiation from the cloud tops of the “intertropical convergence zone” locally reverses the equatorial solenoidal field to produce two new lines of convergence, one on each si...

The main purpose of the paper is to develop a mathematical method for the calculation of the dynamics of the upper atmosphere including nonlinear terms with the aim of replacing the “second heat source” of the Harris-Priester model by taking into account horizontal wind systems. A system of hydrodynamic and thermodynamic equations is set up for a two-dimensional dynamic model of the upper atmosphere representing the diurnal behavior of the atmospheric parameters within the equatorial plane during the time of the equinox. An approximate WKB solution, taking into account heat conductivity, viscosity and external heat sources, leads to a generalized form of gravity waves with periods of one day. The solution of the one-dimensional quasi-static Harris-Priester model is treated explicitly. An estimate of the influence of horizontal winds on the heat balance suggests that a wind of the order 200 m sec−1 can behave like a “second heat source” shifting phase and the amplitude of the calculated temperatur...

SYNOPSIS In the first part (A) of this paper it is shown that even the latest solar constant observations of the Smithsonian Institution contains a 12-month period, and that its course is exactly the reverse of what it was before the alteration was made in the formula used for the determination of the transparency of the atmosphere. In the second part (B), the changes in the solar constant from 1919–1932, according to Abbot's measurements, are recorded against the sun-spot changes. It seems that the changes in the solar constant are neither parallel to nor opposed to those of the sun spots. But the highest values of the solar constant appear chiefly to occur between the maxima and minima of sun spots, whilst the lowest values occur near the extremes of sun-spot activity. An attempt is made to explain this. In the third part (C) of the work it is pointed out that a similar relationship exists between certain weather phenomena and sun spots.

This paper lays the foundation for development of upper-atmosphere meteorology between heights of 90 and 400 kilometers on the basis of ionospheric measurements. A theory is outlined whereby measurements of the ionosphere permit deduction of five quantities descriptive of the state of the high atmosphere. Application of the theory is made to data from eighteen widely separated locations over the earth for January 1947. Calculations are presented and used in construction of isopleths on a world-wide scale. It is found that cells of high and low temperature are systematically developed in northern and southern hemispheres. Results are compared with findings of other investigators. It is shown that the recombination coefficient between electrons and positive ions is not pressure-sensitive within an ionospheric layer and that the recombination coefficient is not dependent upon the electron density. Temperature gradients found suggest strong wind systems, pronounced convection currents, and considerab...

The hydroxyl bands in the glow emanating from the earth's upper atmosphere are chemically excited. The two possible precursor reactions are O3+H→OH*+O2 and O2*+H→OH*+O. Arguments are advanced in this paper to show that the night-time variations of the emission intensifies stimulated by these two reactions might be characteristically different. The relative importance of the reactions can therefore be judged by a systematic observational study of the intensity variations.

Since the motions of the atmosphere involve the presence of external heat sources and heat sinks, it is important to incorporate these effects into the hydrodynamical theory of air motions. In the discussion contained in this paper a method for accomplishing such a synthesis of hydrodynamics and thermodynamics is formulated for the case of two-dimensional motion. The use of the method is illustrated by an exact integration of the equations for the case of a circular vortex. Possible further elaborations of the method are discussed with a view of throwing light upon the fundamental nature of the general circulation of the atmosphere.

This paper examines the atmospheric states that will cause the formation of condensation trails when the exhaust from a rocket motor mixes with and saturates the atmosphere. It was assumed that the rocket-motor propellants would be aircraft fuel and liquid oxygen. The results of the study are compared with the conditions which are required for the formation of condensation trails from jet-aircraft engines.

Theoretical and experimental studies have led to the development and fabrication of a rocketborne beta-ray densitometer for the direct determination of atmospheric density in the 30–65 km atmospheric interval. Comparison of atmospheric density profiles determined by the Betasonde densitometer with temperature-derived atmospheric density profiles showed excellent agreement to 35 km. Above 35 km, however, the two profiles gradually, diverged until at 50 km the Betasonde-determined density was 35–40%. greater than the temperature-derived density. This paper discusses the results of the cosmic ray count determination in the 0–50 km region with a cosmic ray detector, identical in configuration and sensitivity to the Betasonde, which served as a part of the instrument package on a high-altitude balloon flight from White Sands Missile Range, to 50 km on 22 September 1969. These results indicate that the differences in the comparison atmospheric density values can be attributed to cosmic rays which are d...

The paper describes the techniques developed at Poona for the measurement of electrical potential gradient in the free atmosphere and discusses the results of the observations made over Poona during 1953–1958. The day-to-day and diurnal variations of potential gradient in the troposphere as well as the seasonal variations are discussed. The variation of potential gradient with height follows the theoretical values only during the monsoon months, showing an increase above 300 mb in winter and steady values above 500 mb during summer.