bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Production Rate of Natural Tritium
Authors: Craig Harmon , Lal Devendra 
Published: January 2012

A detailed evaluation is made of the production rate of natural tritium in the pre-thermonuclear epoch. Deuterium and tritium analyses on the same precipitation samples are used to establish the uncontaminated tritium levels in precipitation sampled before the Castle tests, and the tritium balance is calculated for the North American troposphere. The global mean production rate Q̅, calculated from the geochemical inventory, is found to be 0.5 ± 0.3 atoms T/cm2 sec. This value is three to four times smaller than values found previously by such calculations because of the following developments:

The deuterium and tritium data show that the increases in tritium content observed during early thermonuclear tests before Castle are due to addition of synthetic tritium rather than to random fluctuations. The deuterium-tritium relationships are used to establish the general pattern of tritium variations over the North American continent and to evaluate the uncontaminated tritium levels.
The mean stratospheric residence time for tritium is found to be about 1.6 years from studies on fission product fallout and from the latitudinal variation of stratospheric cosmic ray production.
Stratospheric tritium is preferentially injected into the troposphere at high latitudes, as shown by fallout observations. The tritium influx into the North American troposphere is therefore higher than the mean global value.

The predicted production rate is calculated from cosmic ray and nuclear cross section data using the star production rates in the atmosphere. The predicted mean global tritium production rate during an average solar cycle is found to be 0.25 ± 0.08 atoms T/cm2 sec. The variation in the production rate over an average solar cycle is found to be ± 4.5 %.
Within the uncertainties of the data and calculations, the production rates calculated from the geochemical inventory and from the cosmic ray data are in agreement, and there is thus no observational evidence for accretion of tritium from an extra-terrestrial source.
Cloud Patterns in Hurricane Daisy, 1958
Authors: Malkus Joanne S. , Ronne Claude , Chaffee Margaret 
Published: January 2012

Maps of clouds in Hurricane Daisy, 1958, have been constructed from aerial ciné photographs made by the aircraft of the National Hurricane Research Project of the U.S. Weather Bureau. Films suitable for quantitative analysis were available for four flights on three separate days during the formation, deepening, and maturity of this small but intense Atlantic hurricane which moved slowly over the ocean in the vicinity of 30° N, 76° W. Clouds were located within 5–10 nautical miles relative to the known aircraft path (in coordinates with origin at hurricane center) by a modified method of aerial photogrammetry using the accurately known timer for the image to cross a frame. Horizontal and vertical dimensions of important clouds and cloud forms have been measured to within about 10 %.
The photographic maps are compared to radar analyses made from the same and also different aircraft (U.S. Navy WV-4). The most significant results are first the remarkable persistence of recognizable cloud patterns throughout the three days studied, during which the storm deepened and moved about 200 nautical miles and second, the concentration of convective activity into a few lines of cumulonimbus towers which even on the mature day occupied only about 4 % of the rain area (radius within about 200 nautical miles).
On the Steady Flow of a Fluid of Variable Density Past an Obstacle
Authors: Drazin Philip G. 
Published: January 2012

A model of steady airflow past a three-dimensional mountain is considered. The fluid is inviscid and incompressible. The flow is under the influence of gravity, but for most of the work the earth's rotation is neglected. Far upstream the flow is parallel and horizontal, the velocity U(z) and the density ƍ(z) varying with height z. By use of conservation of density and head along streamlines, and thence of the dependence of density and head on one variable z0 only, the equations of motion are simplified, z0 (r) being the height far upstream of the streamline through the point with position vector r. The flow is considered first with small and then with large density variations far upstream. In the case when these variations are small, results of the known method of simple-shear secondary flows are rederived and extended.
The chief consideration of this paper is the buoyancy effects of large variations of density in the oncoming stream. For simplicity, the shear far upstream is neglected. The primary and secondary velocities are found for large Richardson number (proportional to gdƍ/ƍdz0). The method is time-symmetric and analogous to taking the first two terns of the Janzen-Rayleigh expansion, the inverse of the Richardson number being the analogue of the square of the Mach number. The primary velocity, for infinite buoyancy forces, is horizontal, the flow in each horizontal plane being the same as the potential flow about the section of the obstacle in that plane. In general there is shear between horizontal planes, with horizontal primary vorticity. The secondary flow is found explicitly for a circular cylinder with vertical axis and for a hemisphere resting in a horizontal plane. The secondary approximation is not uniformly valid near the horizontal plane at the height of the top (if any) of the obstacle. Near that plane there is an inviscid shear layer, and the velocity gradient cannot be neglected, however large the Richardson number.
Convection in Conditionally Unstable Atmosphere
Authors: Kuo H. L. 
Published: January 2012

The analysis has shown that if the stratification is unstable for ascending motion over an infinite area and stable for descending motion, and small random perturbations of various scales are introduced, the final disturbance evolved will have the dimension of a cumulus cloud. The stable stratification in the descending region has the effect of increasing the critical lapse-rate and narrowing the ascending region and making the descending motion widespread, so that the centers of the ascending regions are further apart. The distance estimated from the theoretical analysis agrees favorably with those obtained from satellite observations.
The distributions of the various perturbation quantities pertaining to a circular symmetrical disturbance have been obtained. They show many resemblances to the corresponding distributions in tropical storms. Since the main source of energy of the mature tropical storms is the latent heat of condensation, it is really tempting to attribute the formation of these large-scale disturbances directly to convection in conditionally unstable air. However, the analysis shows that some organizing mechanisms are needed in order to channel the release of the energy of unstable stratification into a large scale circulation.
On the theory of the general circulation of the atmosphere
Authors: Adem Julián 
Published: January 2012

Applying the conservation of energy principle to the incoming solar radiation and to the long-wave radiation, a heating mechanism of the atmosphere is introduced. A simplified emission spectrum of the atmosphere with one transparent region is used. The surface of the earth and a cloud layer are considered as black bodies.
A simplified model of the atmosphere containing the coupling between dynamical and thermodynamical processes is presented. The equations that give the temperature, the excess of radiation and the mean zonal wind for each day of the year are derived. The temperature is given by a second order differential equation that can readily be solved. The zonal wind and the excess of radiation are explicit functions of the temperature.
If in the computations we postulate that the addition of energy by processes other than radiation is a constant, the solution agrees remarkably well with the observed values, except in the months of May, June and July.
It is shown that using only meridional turbulent diffusion transport of heat by large eddies, the required transport is accomplished. The theoretical solution requires a transport with the following exchange coefficients: 5 × 1010 cm2 per sec in February and in March, 4.5 × 1010 in October, 4 × 1010 in January, 3.5 × 1010 in November, 3 × 1010 in September and in December, 2 × 1010 in April, 0.25 × 1010 in August, and zero in May, June and July. There are two maxima of the value of the exchange coefficient: one in February and the other in October. The order of magnitude of the values of the exchange coefficient of our solution is in complete agreement with the value corresponding to the migratory cyclones and anticyclones of the middle latitudes, treated as turbulent eddies, which is equal to 5 × 1010.
The theoretical solution correctly gives the position and strength of the jet stream, except in May, June and July. Therefore we can conclude that, except in these months, the mean daily circulation is mainly a result of the transfer of energy by radiation processes and the turbulent meridional transport of heat by the migratory cyclones and anticyclones.
Structural characteristics of the subtropical jet stream and certain lower-stratospheric wind systems
Authors: Newton Chester W. , Persson Anders V. 
Published: January 2012

Analyses of the wind field are presented for several caws, which illustrate the considerable variability in structure of the subtropical jet stream. Two cores of strongest wind are common, one lying in the break between the middle and subtropical tropopause and the other often lying above the subtropical tropopause. The layer of strongest wind on the cyclonic flank slopes upward toward north and is often identifiable as a discrete wind-speed maximum several kilometers above the polar-front jet stream. On the anticyclonic flank, the lower subtropical jet slopes downward toward south and is sometimes stronger than the higher-level layer of maximum wind.
Although the broad-scale structure of the wind fields is qualitatively in accord with the solenoid field, large deviations from the thermal wind relationship are found in layers of restricted depth. Measured vertical shears are often double or triple the size of the thermal shear, and in certain regions the thermal and actual shears are of opposite sign. These deviations are shown to be associated with inertial effects arising from curvature of the flow, and from variations of curvature with height.
An example is given illustrating the shallow filaments of strong wind sometimes found in the lower stratosphere above the tropospheric jet streams. These are not indicated by the thermal field, and are evidence of strong domination by inertial effects.
Breaks in the Indian summer monsoon as a phenomenon of interaction between the easterly and the sub-tropical westerly jet streams
Authors: Ramaswamy C. 
Published: January 2012

The present paper contains the results of the study of a synoptic situation over India during a period of 8 days in which normal monsoon conditions were followed by a break and were further followed by a return to normal monsoon. This study has shown that during breaks in the monsoon, a trough in the middle latitude westerlies with a jet embedded in it increases considerably in its amplitude and gets retarded as it moves into the Tibetan Plateau on account of its entering a region of weaker basic current. The large-amplitude trough weakens or destroys completely the Tibetan high at the 500 mb level and appreciably weakens the easterlies at the higher levels to the south of the Himalayas. Protruding into India and Pakistan, the large amplitude trough contributes to the development of heavy rainfall along and near the foot of the Himalayas which is characteristic of the break conditions. The southward protrusion of the trough and its subsequent movement eastward, is also indirectly responsible for a corresponding shift of the high over Iran and Arabia, which, in its turn, seems to lead to the formation of a secondary jet core in the easterlies west of 80° E between 20° N and 25° N. Consequent on the above developments, the westerly jet which had retreated to the north of the Himalayas at the time of the onset of the monsoon reenters the Indo-Pakistan sub-continent during the breaks. Thus we see during break conditions, the remarkable spectacle of two jets of entirely different types-the easterly and the sub-tropical westerly—within a short latitudinal distance of each other and dynamically interacting with each other.
The above detailed study, supplemented by a general examination of the monthly mean 700 mb charts for the northern hemisphere for a period of 10 years, suggests that active monsoon over India is closely associated with high index circulation in middle latitudes over Asia and neighbourhood, while weak monsoon is closely associated with low index circulation over the same region.
Convective instability in a two-layer fluid heated uniformly from above
Authors: Welander Pierre 
Published: January 2012

A fluid in which the dynamic and thermodynamic coefficients (&mu;, &alpha;, &chi;, cp etc.) vary vertically may become unstable when it is heated uniformly from above, assuming that the basic stratification is gravitationally stable and that the thermal expansion coefficient is positive. This &ldquo;anti-convection&rdquo; is studied in the special case of a fluid composed by two semi-infinite layers, each of which has constant coefficients. In the theory the Boussinesq approximation is used for each layer separately, and the interface is assumed to be plane. These assumptions seem justified in the present problem.Instability is favoured when the thermal expansion coefficient and the conductivity are large in one of the layers and small in the other layer. A necessary condition for instability is that the ratio μ1 ɑ1Cp2/μ2ɑ2Cp1 is larger than 9 (or smaller than 1/9), where &mu; is the dynamic viscosity, &alpha; the thermal expansion coefficient, and cp the specific heat per unit mass. When this condition is fulfilled instability will occur for sufficiently large values of the ratio Χ1/Χ2 (small values, respectively), where Χ is the thermometric conductivity.The convection cells are confined to a region next to the interface. Small cells have comparable width and height, while larger cells are flattened in proportion to the 1/6 power of the Rayleigh number. Because of counteracting non-linear effects the convective motion cannot grow very large, the vertical velocities can at most be of order Χ/D, where D is the scale of the cell. It is suggested that cells with Rayleigh numbers of order unity dominate the picture in finite amplitude situations.The driving energy comes from a region next to the boundary in the fluid layer having the larger thermal expansion and conductivity. Any motion started in the other layer creates thermal perturbations that are conducted into this region inducing a reversed circulation. When the thermal expansion coefficient is large this reversed circulation becomes strong. Through the frictional coupling it can directly amplify the primary motion and an instability develops.It should be possible to observe the instability in a laboratory experiment. A mercurywater system seems suitable for this purpose. The theoretical analysis shows that instability occurs when heating is applied at temperatures below 18°C.Geophysical and astrophysical applications seem possible. As example, the instability may appear at the interface between the atmosphere and the sea. An air-water system is stable under laboratory conditions, but in nature the existing eddy friction and conduction change the conditions considerably, and such as to favour the occurrence of the instability.
The Circulation of the High Troposphere over China in the Winter of 1945–46
Authors: Yeh Tu-Cheng 
Published: January 2012

The paper studies the structure of the high troposphere over China in the autumn
of 1945 and winter of 1945–46. The principal feature is the existence of two belts of
maximum westerlies, one flowing around the southern and the other around the northern
edge of the Tibetan Plateau. The southern jet stream (the main one) is extremely
stationary in position. Its speed increases downstream beyond the edge of the Asiatic
continent. The onset of this southern jet stream is abrupt in the middle of October over
central and southwestern China and advances downstream at a speed of about 3° longitude
per day. South of this main jet stream is a belt of extremely uniform absolute
vorticity which is zero in December and January. In spite of the existence of zero
absolute vorticity the circulation above 15,000 feet is strikingly stable. Below 10,000
feet is the regular procession of warm troughs and cold ridges. Comparison with the
conditions along 76° E and the east coast of United States has also been made. The
difference in the structure of the basic current along the east coasts of the two
continents suggests an explanation of the observed formation of winter typhoons off the
Chinese coasts versus the non-existence of such storms in the Caribbean Sea in the cold
season.
Eddy Flux of Heat and Momentum during Two Years at Stockholm-Bromma
Authors: Nyberg A. , Schmacke E. 
Published: January 2012

The eddy flux of momentum, sensible heat and latent heat has been computed from measured temperature, humidity and wind data from the aerological station Bromma 59° 21ʹ N, 17° 57ʹ E. The results obtained have been compared with similar computations for Larkhill 51° 11ʹ N, 01° 48ʹ W made by Priestley. A comparison has also been made with values obtained by using geostrophic winds kaken from synoptic charts. An estimation of the heat and momentum gained by eddy flux in the zone between 51° N and 59° N and north of 60° N has been made.
On the Chemical Climate and its Variation with the Atmospheric Circulation Pattern
Authors: Rossby C.-G. , Egnér H. 
Published: January 2012

A study of the chemical composition of monthly precipitation samples from a number of stations in Sweden brings out the existence of significant variations in the relative proportions of chlorides and sodium depending upon the general character of the prevailing circulation. In maritime westerly flows the weight ratio of chloride to sodium decreases eastward to values which lie far below the value characteristic of sea water. In precipitation falling from arctic or polar continental air masses the chloride component is almost completely absent. The highest amounts of chlorides relative to sodium are observed in precipitation from warm and most air masses reaching Sweden from the south or southeast.
Significant variations are observed also in the yearly means of the sodium and sulphur deposits depending upon the dominance of maritime or continental air currents.
A sketch map of the “average” chloride concentration in European precipitation prepared from miscellaneous older data lends support to the results of the analysis of the monthly data. The separation of the chemical components indicated by this study would seem to be of considerable geochemical interest since it would permit different maritime salts to be deposited in widely separated parts of the continents. It is not inconceivable that a detailed study of the association between different circulation patterns and the corresponding chemical climates might permit us to draw inferences concerning variations in the atmospheric circulation during post-glacial times, e.g. from the data on the chemical stratification in raised bogs now becoming available through the investigations by Mattson and Koutler-Andersson.
Tests of the Salt-Nuclei Hypothesis of Rain Formation
Authors: Woodcock A. H. , Blanchard D. C. 
Published: January 2012

Atmospheric chlorides in sea-salt nuclei and the chlorides dissolved in shower rainwaters were recently measured in Hawaii. A comparison of these measurements reveals the remarkable fact that the weight of chloride present in a certain number of nuclei in a cubic meter of clear air tends to be equal to the weight of chloride dissolved in an equal number of raindrops in a cubic meter of rainy air. This result is explained as an indication that the raindrops grow on the salt nuclei in some manner which prevents a marked change in the distribution of these nuclei during the drop-growth process.
The data presented add new evidence in further support of the salt-nuclei raindrop hypothesis previously proposed by the first author (WOODCOCK, 1952).
Mineral Composition of Rainwater
Authors: Larson T. E. , Hettick Irene 
Published: January 2012

Analyses of 62 rainwater samples collected at the University of Illinois Airport near Savoy, Ill., showed that on the basis of equivalent concentrations, the chloride is equal to the sum of sodium and potassium. Sodium was three times the potassium. Calcium plus magnesium was 10 times the chloride and equal to the sum of the bicarbonate and sulfate. The sulfate was equal to twice the sum of ammonium and nitrate.
These results indicate salt from sea mist to constitute a negligible proportion of the mineral content. They also indicate the presence of air pollution by the combustion of fuel.
Trade Cumulus Cloud Groups: Some Observations Suggesting a Mechanism of Their Origin
Authors: Malkus Joanne Starr 
Published: January 2012

On a recent field trip to the western Caribbean, temperature gradients in the surface layers of the trade-wind oceans were found and related to the presence of cumulus cloud groups. The cloud groups generally formed over and slightly downwind of warm spots which were several kilometers in extent along the wind and 0.1—0.3° C in amplitude. Clouds were not found in the absence of warm spots although warm spots were occasionally encountered without clouds.
Air circulations, similar to but weaker than those produced by heated land masses, are hypothesized to exist over oceanic warm spots and their magnitude is estimated from previous work on heated islands. Observed differences in low-level moisture structure between clear and cloudy areas may be interpreted in terms of such circulations and their evolution with time. Some suggestions are made concerning the life cycles of trade cumuli.
The Natural Distribution of Radiocarbon and the Exchange Time of Carbon Dioxide Between Atmosphere and Sea
Authors: Craig Harmon 
Published: January 2012

Steady-state equations governing the transfer and distribution of a radioactive isotope between its various exchange reservoirs are applied to the natural distribution of carbon 14. The radiocarbon enrichment or depletion in each reservoir, relative to the hypothetical state in which mixing is infinitely faster than the decay rate, is evaluated as a quantitative function of the exchange rates between the reservoirs. From the observed distribution of C12, C13, and C14 in the atmosphere, biosphere, and sea, and from the estimated production rate of C14 by cosmic rays, the residence time of a carbon dioxide molecule in the atmosphere, before entering the sea, is found to be between four and ten years.
The atmospheric residence time may also be evaluated, independently of the estimated C14 production rate, by considering the functional dependence of the C14 concentration in the oceanic mixed layer on the residence times in the atmosphere and the deep sea. This second method of evaluation also leads to an atmospheric residence time of about seven years. The average annual exchange flux of carbon dioxide into the sea is thus about 2 × 10−2 moles per square centimeter of sea surface. The average residence time of carbon dioxide in the deep sea is estimated as probably not more than about 500 years.