Showing papers in "Tellus A in 1949"
TL;DR: In this paper, it was shown that a simple state of steady baroclinic large-scale atmospheric motion is almost invariably unstable, and that such states of motion can be represented by components of a certain simple type, some of which grow exponentially with time.
Abstract: By obtaining complete solutions, satisfying all the relevant simultaneous differential equations and boundary conditions, representing small disturbances of simple states of steady baroclinic large-scale atmospheric motion it is shown that these simple states of motion are almost invariably unstable. An arbitrary disturbance (corresponding to some inhomogeneity of an actual system) may be regarded as analysed into “components” of a certain simple type, some of which grow exponentially with time. In all the cases examined there exists one particular component which grows faster than any other. It is shown how, by a process analogous to “natural selection”, this component becomes dominant in that almost any disturbance tends eventually to a definite size, structure and growth-rate (and to a characteristic life-history after the disturbance has ceased to be “small”), which depends only on the broad characteristics of the initial (unperturbed) system. The characteristic disturbances (forms of breakdown) of certain types of initial system (approximating to those observed in practice) are identified as the ideal forms of the observed cyclonc waves and long waves of middle and high latitudes. The implications regarding the ultimate limitations of weather forecasting are discussed. DOI: 10.1111/j.2153-3490.1949.tb01265.x
1,609 citations
TL;DR: In this article, it was shown that the large-scale quasi-stationary disturbances of the middle-latitude westerlies are produced by the forced ascent of the westerly current over the continental land masses.
Abstract: It is shown that the large-scale quasi-stationary disturbances of the middle-latitude westerlies are produced by the forced ascent of the westerly current over the continental land masses. Friction is found to have an important modifying effect on the motion. Using these results a numerical method is devised for predicting the height profile of the 500 mb pressure surface at a fixed latitude. The method involves the use of the notion of an “equivalentbarotropic atmosphere” and of the geostrophic approximation. Six actual forecasts are made for a period of one day and the results compared with observation. The accuracy obtained is thought to justify incorporation of the method into day-to-day forecast procedures. DOI: 10.1111/j.2153-3490.1949.tb01258.x
547 citations
TL;DR: In this article, a discussion is given concerning the construction and interpretation of a diagram which shows longitude and intensity of troughs and ridges at the 500 mb level in middle latitudes as a function of time.
Abstract: A discussion is given concerning the construction and interpretation of a diagram which shows longitude and intensity of troughs and ridges at the 500 mb level in middle latitudes as a function of time. DOI: 10.1111/j.2153-3490.1949.tb01260.x
258 citations
TL;DR: In this article, an aerological analysis of a series of rapid-moving frontal waves associated with a well developed zonal current over central Europe is presented, where the gradual destruction of this zonal flow through a retrograde blocking "wave" is described.
Abstract: This paper contains an aerological analysis of a series of rapid-moving frontal waves associated with a well developed zonal current over central Europe. The gradual destruction of this zonal flow through a retrograde blocking “wave” is described. The relationship between the blocking process and the deepening of series of waves approaching the blocking zone from North America is discussed. The observational data and conclusions from this aerological study are presented for the purpose of rendering some assistance to theoreticians investigating atmospheric wave motions, by providing a few numerical values for certain characteristic parameters of these waves and by calling attention to a factor which appears to play a significant role in the deepening of certain types of extra-tropical wave cyclones, viz. the variation with longitude of the basic current pattern. DOI: 10.1111/j.2153-3490.1949.tb01257.x
205 citations
TL;DR: In this paper, a special type of cyclones formed in the belt of the upper westerlies is described, where the cold air in the southern part of the trough becomes separated from the cold water in the north.
Abstract: This study deals with a special type of cyclones formed in the belt of the upper westerlies. The development begins as wave-like deformation of the upper flow and this deformation increases in amplitude until the cold air in the southern part of the trough becomes separated from the cold air in the north. The process of separation may be described as a cutting-off of a cold vortex. The process is described in some detail for a special case. High-level cyclones formed in this manner are not rare: on the contrary, such upper air disturbances are of great importance for the weather phenomena in certain regions, especially at latitudes between 30°–50° N. They can also be regarded as an important link in the large-scale quasi-horizontal meridional exchange of air masses. DOI: 10.1111/j.2153-3490.1949.tb01925.x
74 citations
TL;DR: In this article, the authors discuss three different frictional effects and one effect leading to orographically conditioned convergence at quasi-isophysic flow, illustrated by Scandinavian and Dutch rainfall maps of remarkable special cases of maximum coastal precipitation.
Abstract: The coastal maxima of rainfall during autumn and winter cannot be explained alone by the classical theory of orographic precipitation. Three different frictional effects , and one effect leading to orographically conditioned convergence at quasi-isophysic flow, are discussed and illustrated by Scandinavian and Dutch rainfall maps of remarkable special cases of maximum coastal precipitation. The rainfall maps over Holland even hint secondary maxima further inland, at zero-level and parallel to the coastal maximum; they might be explained in connection with standing waves in the sense of Queney and others. With all these effects a low condensation level and an efficient precipitation release , by ice-nuclei or in other ways, seem indispensable to cause intense orographic condensation and bring its results promptly down to the earth. As stated in article I such orographic cloud-systems, if lacking an efficient release, just represent the clouds where artificial seeding might materially increase precipitation, because (1) condensation may for a long time keep intense and stationary, and (2) the clouds may keep releasable but unreleased. This increase, if at all possible, would diminish precipitation inland where it is much more useful. — A better scheme would therefore be trying to overseed coastal cloud-systems in order to prevent their precipitation release, and thereby increasing precipitation inland, provided the overseeding could be avoided there. This overseeding process might also be used for dissipating inland Cunb, but presumably not for dissipating tropical hurricanes. The generally accepted idea of the increase of precipitation with height is often, e.g. in Norway, contradicted by individual cases with a marked decrease from the very coast and upward when moving inland. A rational attack on this problem was hitherto impossible because the complex nature of orographic precipitation (hinted above) was not recognized. - Outside the Tropics excessive precipitation needs low cloud formed by an intense updraft at high temperature (= maximum condensation and minimum evaporation) in continual contact with an upper cloud (part) surpassing the —10 p C-level, or seeded artificially (= efficient precipitation release). These conditions will be fulfilled in certain orographic clouds discussed above, and within some convective and frontal clouds. DOI: 10.1111/j.2153-3490.1949.tb01264.x
55 citations
TL;DR: Different kinds and degrees of colloidal and thermodynamical instability of diverse systems of cloudparticles, partly leading to release of precipitation, are discussed, aiming at estimating the possible effect of “seeding” clouds artificially with ice-nuclei.
Abstract:
Different kinds and degrees of colloidal and thermodynamical instability of diverse systems of cloud-particles, partly leading to release of precipitation, are discussed, aiming at estimating the possible effect of “seeding” clouds artificially with ice-nuclei. — A low ratio v of supercooled cloud-droplets versus ice-crystals (v ≤ 1) would ensure very rapid glaciation of the cloud, but no precipitation release and no substantial improvement of visibility within it: overseeding. High values of v (> 106) would lead to the formation of big, though very sparse precipitation elements, but not noticeably improve visibility within the cloud: underseeding. Favourable values of v seem to lie around 10.3 — Cases of successful artificial seeding may be explained by natural seeding indirectly caused by the artificial one: double release. — Lastly, an inventory of the actual tropospherical clouds and cloud systems indicates that the main possibility for causing considerable artificial rainfall might be found within certain kinds of orographic cloud systems, to be treated in a following article.
43 citations
TL;DR: In this paper, different kinds and degrees of colloidal and thermodynamical instability of diverse systems of cloudparticles, partly leading to release of precipitation, are discussed, aiming at estimating the possible effect of “seeding” clouds artificially with ice-nuclei.
Abstract: Different kinds and degrees of colloidal and thermodynamical instability of diverse systems of cloud-particles, partly leading to release of precipitation, are discussed, aiming at estimating the possible effect of “seeding” clouds artificially with ice-nuclei. — A low ratio v of supercooled cloud-droplets versus ice-crystals (v ≤ 1) would ensure very rapid glaciation of the cloud, but no precipitation release and no substantial improvement of visibility within it: overseeding. High values of v (> 10 6 ) would lead to the formation of big, though very sparse precipitation elements, but not noticeably improve visibility within the cloud: underseeding. Favourable values of v seem to lie around 10. 3 — Cases of successful artificial seeding may be explained by natural seeding indirectly caused by the artificial one: double release. — Lastly, an inventory of the actual tropospherical clouds and cloud systems indicates that the main possibility for causing considerable artificial rainfall might be found within certain kinds of orographic cloud systems, to be treated in a following article. DOI: 10.1111/j.2153-3490.1949.tb01926.x
39 citations
TL;DR: In this paper, the authors investigated the rate of dispersion of solitary, quasihorizontal atmospheric disturbances with the aid of a simple barotropic model of the atmosphere and found that in low latitudes the dispersion is extremely rapid, in good agreement with the observed absence of all but the smallest solitary disturbances.
Abstract: In this paper an attempt is made to investigate the rate of dispersion of solitary, quasihorizontal atmospheric disturbances with the aid of a simple barotropic model of the atmosphere. In low latitudes the dispersion is found to be extremely rapid, in good agreement with the observed absence of all but the smallest solitary disturbances. In high latitudes the dispersion is slow, permitting the establishment of persistent solitary circulation patterns. The theory appears so throw some light on the geographic distribution of the interdiurnal variability in the height of the 500 mb surface and on the relatively frequent occurrence of planetary waves with a wave length of 120 longitude degrees. A fuller treatment is now being published by my associate, Dr. T. C. Yeh. DOI: 10.1111/j.2153-3490.1949.tb01928.x
38 citations
TL;DR: In this paper, the fundamental frequencies of these oscillations are determined and some comments are made with regard to their dispersive properties, taking into account the existence of a zone of intense westerly circulation found in this region of the atmosphere.
Abstract: Oscillations of a barotropic model of the upper troposphere are studied, taking into account the existence of a zone of intense westerly circulation found in this region of the atmosphere. The fundamental frequencies of these oscillations are determined and some comments are made with regard to their dispersive properties. DOI: 10.1111/j.2153-3490.1949.tb01266.x
21 citations
TL;DR: In this article, experiments were carried out in a model test tank filled with dried sand; and in this a vein of iron ore or other materials Artificial lightning discharges against the surface of the test tank were undertaken by the aid of an impulse generator at voltages of one million volts and spark lengths of 75 and 170 cm respectively.
Abstract: To investigate the influence of lightning strokes on surfaces with geologically non-homogenous structures, experiments were carried out in a model test tank filled with dried sand; and in this a vein of iron ore or other materials Artificial lightning discharges against the surface of the test tank were undertaken by the aid of an impulse generator at voltages of one million volts and spark lengths of 75 and 170 cm respectively It was found-that a discharge from a positive electrode was pronouncedly influenced by a geological discontinuity as an iron ore vein On the other hand, negative strokes hit the sand surface at random more independent of geological discontinuities The difference in effects from the two polarities is related to the mechanism of the discharges and the development of leaders initiating the main discharges in the form of lightning ones DOI: 101111/j2153-34901949tb01268x
TL;DR: In this paper, different lines of approach to a geochronology of the deep ocean bed, as revealed by sediment cores, are indicated, and different approaches are used to solve the same problem.
Abstract: In this article different lines of approach to a geochronology of the deep ocean bed, as revealed by sediment cores, are indicated. DOI: 10.1111/j.2153-3490.1949.tb01923.x
TL;DR: In this article, a model of the distribution of vertical motion and divergence in the frontal zones of the jet stream is presented, where the authors show that in a deepening trough the cold tropospheric air sinks at the same time as the jet streams increases and the front becomes sharper.
Abstract: Pressure change areas in the 500 mb level move with 60% of the speed of the wind in that level. Advection of cold (warm) air at upper isobaric levels is followed by geopotential falls (rises) at the same levels. The prognostic usefulness of this rule is much higher in the 500 mb level than in the 700 mb level. — There are strong indications of dynamic interaction between flow patterns in distant regions on the hemisphere. A deepening of one upper trough will in special cases lead to a second deepening downstream. — In a deepening trough the cold tropospheric air is shown to be sinking at the same time as the jet stream increases and the front becomes sharper. Models of the distribution of vertical motion and divergence in the frontal zones are given. DOI: 10.1111/j.2153-3490.1949.tb01927.x
TL;DR: In this paper, the authors considered only the simple case of constant incoming penetrating radiation and at the same time a constant effective outgoing radiation from the surface of the medium and showed that the temperature maximum produced during the heating process does not appear at the surface, but rather at some depth below.
Abstract: In view of the fact that large areas of the earth's surface are temporarily or permanently covered by a medium pervious to radiation, i.e. water, snow or ice, attention is directed to that special feature of the heat economy of these media having to do with radiation balance and heat transfer. Primarily, the purpose of the theory is to find an explanation for the observed distribution of temperature within these media. A first attempt to solve this problem was previously made by the author (Reuter 1948 a) in a study of the heat economy of snow cover. The essential basis of the present as well as the earlier treatment lies in the assumption that snow, ice and water, while pervious to insolation, are nevertheless impervious to outgoing radiation. The present paper treats only the simple case of constant incoming penetrating radiation and at the same time a constant effective outgoing radiation from the surface of the medium. One of the principal results is that the temperature maximum produced during the heating process does not appear at the surface, but rather at some depth below. Although the case of water is not treated in this report, the results obtained for ice may be applied, with slight modification, to the case of calm pure water in view of the use of the same coefficients of absorption for both water and ice. DOI: 10.1111/j.2153-3490.1949.tb01263.x
TL;DR: The main purpose of the registrations reported here has been to study the diurnal variations of C. R. and especially to investigate how the amplitude and the phase of the variation depend on the direction of incidence as discussed by the authors.
Abstract: The main purpose of the registrations reported here has been to study the diurnal variations of C. R. and especially to investigate how the amplitude and the phase of the variation depend on the direction of incidence. Since statistical fluctuations will dominate over the significant ones unless a sufficiently large number of coincidences is counted, it has been necessary to use an apparatus with a high counting speed. C. R. has been recorded continuously in Stockholm (magn. lat. 58°) since 1. 10. 1947 by means of large counters in coincidence circuit. Recordings have been made in three different directions simultaneously, and the total number of particles counted amounts to 10 9 . The material has been analyzed with respect to diurnal variation. This analysis definitely proves that the variation is not the same in different directions. A term called C. R. activity has been introduced for the purpose of classifying the registrations according to the magnitude of the variation for each day. An analysis shows that large activity is very often observed during consecutive days. DOI: 10.1111/j.2153-3490.1949.tb01259.x
TL;DR: In this paper, it is shown that the amplitude growth, at a prescribed zonal dimension of the perturbation (wave-length), is primarily controlled by the value of a non-dimensional quantity, viz. the Richardson number, in a similar manner as this number controls the time variation of turbulence to the extent of its being a result of energy redistribution.
Abstract: It is assumed that in horizontally uniform zonal currents certain long waves can grow in amplitude whereby the kinetic energy associated with the growth is drawn from the potential energy of the basic current system. This restriction as to the energy redistribution permits to treat the simultaneous physical changes of state as polytropic, which simplifies considerably the integration of the relevant equations of motion. It is shown that the amplitude growth, at a prescribed zonal dimension of the perturbation (wave-length), is primarily controlled by the value of a non-dimensional quantity, viz. the Richardson number (= static stability divided by the square of the vertical shear of wind), in a similar manner as this number controls the time variation of turbulence to the extent of its being a result of energy redistribution. The derived criterion for instability predicts that all but the very long waves in the middle latitude westerlies are unstable. The intensity of the absolute circulation, in addition to the vertical shear, has an important bearing on the considered phenomenon of instability. This is discussed with regard to the nonequilibrium position of a cold anticyclonic vortex centered at the pole. The stability criterion is also scrutinized as to its validity at tropical latitudes. DOI: 10.1111/j.2153-3490.1949.tb01273.x
TL;DR: A solution of the vorticity equation for a wave pattern changing with time was obtained in this article, where it was shown that such a pattern is necessarily associated with ridge and trough lines which do not run in the south-north direction.
Abstract: A solution of the vorticity equation is obtained for a wave pattern changing with time. It is shown that such a wave pattern is necessarily associated with ridge and trough lines which do not run in the south-north direction. DOI: 10.1111/j.2153-3490.1949.tb01275.x
TL;DR: In this paper, a Straitline boring machine from the Canadian Longyear Co. will be used to extract the structure of the upper parts of the frozen firn in open shafts and the amounts and different kinds of accumulation material (direct precipitation and snow drift) will be determined.
Abstract: U. G. Straitline boring machine from the Canadian Longyear Co. will be used. The structure of the upper parts of the frozen firn will also be carefully examined in open shafts. Besides these more specific investigations, the amounts and differents kinds of accumulation material (direct precipitation and snow drift) will be determined, as well as the ablation quantity (melting, evaporation, and wind corrosion). DOI: 10.1111/j.2153-3490.1949.tb01930.x
TL;DR: In the last war the Chalmers University of Technology, Gothenburg, started a small ionospheric observatory at Askim (57°14' N, 11°59' E) six miles south of the city as mentioned in this paper.
Abstract: During the last war the Telecommunications Laboratory of the Chalmers University of Technology , Gothenburg , started a small ionospheric observatory at Askim (57°14‘ N, 11°59‘ E) six miles south of the city. Fixed frequency recordings were begun in 1941 and a year later, in 1942, a semi auto- matic multi-frequency recorder was put in opera- tion. Already during the first years of operation of the Askim observatory, which unfortunately had to be very irregular during the war, a de- finite need was felt for a recording sister-observ- atory in the very north of Sweden where the auroral disturbances are much more frequent than at Gothenburg. DOI: 10.1111/j.2153-3490.1949.tb01276.x
TL;DR: In this paper, the authors describe a new type of recorder for ionospheric sounding, which covers the frequency spectrum 1 to 20 Mc/s in 30 seconds and is for that reason of great value for investigations in the polar regions.
Abstract: This article gives a description of a new type of recorder for ionospheric sounding. The recorder covers the frequency spectrum 1 to 20 Mc/s in 30 seconds and is for that reason of great value for investigations in the polar regions, where ionospheric conditions are very fluctuating. The use of a wide band transmitter and receiver has made the short sweep time possible. Only one variable capacitor rotating at low speed is necessary. Automatic tracking between receiver and transmitter is secured through the use of a heterodyne system. Samples of records obtained at Kiruna since the beginning of observations in July 1948 are shown. DOI: 10.1111/j.2153-3490.1949.tb01272.x
TL;DR: In this article, a procedure is outlined for estimating numerically the factors which favor or oppose the development of thunderstorms, and the resulting "thunderstorm tendencies" may be represented on synoptic charts; examples are given of the use of these charts in forecasting.
Abstract: A procedure is outlined for estimating numerically the factors which favor or oppose the development of thunderstorms. The resulting “thunderstorm tendencies” may be represented on synoptic charts; examples are given of the use of these charts in forecasting. DOI: 10.1111/j.2153-3490.1949.tb01270.x
TL;DR: In this article, a short review of the development of artificial seismology is given, and a description of the modern field procedure when using the seismic refraction method for measuring of small depths, of the order of only a few meters.
Abstract: After a short review of the development of “artificial seismology” a description is given of the modern field procedure when using the seismic refraction method for measuring of small depths, of the order of only a few meters. A small portable instrument equipment used for this purpose is described. The theoretical and physical basis for the seismic exploration method is briefly discussed, and by an example it is shown that laboratory tests on rock samples can be used to calculate the transmission velocity of seismic waves. Some examples are given on the use of the seismic refraction method for civil engineering work. It is also related how the small portable instrument equipment previously described was used to measure the thickness of a glacier by means of the seismic reflection method. Repeated reflections (reverberations) were obtained and the smallest depth accurately determined in this way was 96 m. DOI: 10.1111/j.2153-3490.1949.tb01271.x
TL;DR: A survey of the scope and the activities of the radiation Com- missions can be found in this article, where the authors present an overview of the history of the field of radiation communications.
Abstract: In many scientific activities the war caused an interval of stagnation. We are now faced not only with the problem of taking up and reestablishing activities interrupted several years ago, but also with the problem of reorganizing these activities on a new basis with due regard to present needs. With these conditions in mind an historic survey of the scope and the activities of the Radiation Com- missions may be of interest. DOI: 10.1111/j.2153-3490.1949.tb01267.x
TL;DR: SVERDRUP as mentioned in this paper was the leader of the first Norwegian Polar Expedition, which left Norway in November 1949 for the Western parts of Queen Maud Land, in about long.
Abstract: This expedition, the financial backing of which has now been secured, is planned to leave Norway in November 1949 for the Western parts of Queen Maud Land, in about long. 0°, to spend two winters there and return to Europe in 1952. As this district was claimed by Norway in January 1939, and recognized as a dependency of that country in June 1948, and as Norway is paying far more towards the expedition than either of the other countries, the expedition will sail under the Norwegian flag, and its leader will be Professor H. U. SVERDRUP, the Director of “Norsk Polarinstitutt”. The wintering group will consist of 14 men, of whom 6 are scientific experts, 2 from each country. This expedition was first proposed by me in Oslo and London in May 1946, and committees appointed for that purpose by the three countries have since been cooperating in working out the plans. DOI: 10.1111/j.2153-3490.1949.tb01929.x
TL;DR: In this paper, the authors derived a 48 hour formula for upper air pattern types, such as sinusoidal profiles of different wave-length, and some types of regular but assymetric quasi-sinusoidal profile, the purpose of these tests being to ascertain the nature of the circulation changes implied by the Charney-Eliassen method.
Abstract: J. G. CHARNEY and A. ELIASSEN (1949) have proposed a numerical forecast-method for the height profile of the 500 mb-surface at a fixed latitude, and they have also calculated the constants necessary for 24 hour forecasts at 45° N. From those constants the author has derived a 48 hour formula, which has been tried on some simple and regular upper air pattern-types, such as sinusoidal profiles of different wave-length, and some types of regular but assymetric quasi-sinusoidal profiles, the purpose of these tests being to ascertain the nature of the circulation changes implied by the Charney-Eliassen method. DOI: 10.1111/j.2153-3490.1949.tb01274.x
TL;DR: In this paper, a special type of atmospherics produced within snow squalls is discussed, and the theoretical principles and methods of measuring the atmospheric properties by means of open-air antenna circuits and suitable cathode ray oscillographs are discussed.
Abstract: This article deals with a special type of atmospherics produced within snow squalls. It discusses the possibilities of the genesis of such atmospherics. There is also a discussion of the theoretical principles and methods of measuring atmospherics by means of open-air antenna circuits and suitable cathode ray oscillographs. The article contains examples of typical meteorological situations with atmospherics of the type discussed. Special attention has been given to a case where a bank of cumulo-nimbus clouds was located near the east coast of the Baltic and visible from Uppsala. Exemples are given of the typical variation forms of atmospherics produced in squalls within a limited range inside this cloud-bank. DOI: 10.1111/j.2153-3490.1949.tb01256.x
TL;DR: In this paper, the results of the first half year are presented and analyzed in this preliminary communication, and the statistical distribution of radiation sources of stronger and weaker fade-outs across the solar disk is shown.
Abstract: Regular recordings of ionspheric effects of solar flares with different kinds of apparatus were started at the Geophysical Observatory, Chalmers University of Technology, Gothenburg early in 1948. The results of the first half year are presented and analysed in this preliminary communication. The statistical distribution of radiation sources of stronger and weaker fade-outs across the solar disk is shown. The magnitude and probability of the absorption of the ultraviolet fade-out radiation in the solar corpuscular beam is discussed. DOI: 10.1111/j.2153-3490.1949.tb01924.x
TL;DR: The theory of isostasy supposes that, in regions which have not been disturbed recently, each vertical column of the earth's crust with a certain minimum radius and extending to a depth of about 100 km has approximately the same mass.
Abstract: The theory of isostasy supposes that, in regions which have not been disturbed recently, each vertical column of the earth's crust with a certain minimum radius and extending to a depth of about 100 km has approximately the same mass. To find the deviation from this approximation in a given region, the density must be assumed as a function of depth. Such assumptions used at present for calculations are discussed critically. The resulting errors are greater than it is normally beleaved; errors in the calculated isostatic gravity anomalies exceeding ten milligals must be expected in certain regions. Systematic errors result from the usual assumption in routine calculations that the mean density in the earth's crustal layers under the bottom of the Pacific and in the continental areas is the same, and that in both the difference between the density of the layers above about 30 km and the layers below this depth is 0.6. The processes producing and maintaining isostatic equilibrium are discussed.
TL;DR: In this paper, a model of the U.S. thunderstorm structure, life cycle and thermodynamics has been proposed, which is based on the model proposed in this paper.
Abstract: Certain intensive investigations into the nature of thunderstorms in the United States have resulted in a new model of thunderstorm structure, life cycle and thermodynamics. Thunderstorms and their effects have been investigated by airplanes, radar, surface micronetworks and swarms of balloons. Some of the more significant aspects of these measurements are described. A comprehensive final report will be published soon by the U. S. Government. DOI: 10.1111/j.2153-3490.1949.tb01269.x