Visibility Phenomena Research Articles

Visibility phenomena in hypercubes

We study the set of visible lattice points in multidimensional hypercubes. The problems we investigate mix together geometric, probabilistic and number theoretic themes. For example, we prove that almost all self-visible triangles with vertices in the lattice of points with integer coordinates in W=([0,N]∩Z)d are almost equilateral having all sides almost equal to dN/6, and the sine of the typical angle between rays from the visual spectra from the origin of W is, in the limit, equal to 7/4, as d and N/d tend to infinity. We also show that there exists an interesting number theoretic constant Λd,K, which is the limit probability of the chance that a K-polytope with vertices in the lattice W has all vertices visible from each other.

Relationship between Visibility, Air Pollution Index and Annual Mortality Rate in Association with the Occurrence of Rainfall—A Probabilistic Approach

An innovative method was proposed to facilitate the analyses of meteorological conditions and selected air pollution indices’ influence on visibility, air quality index and mortality. The constructed calculation algorithm is dedicated to simulating the visibility in a single episode, first of all. It was derived after applying logistic regression methodology. It should be stressed that eight visibility thresholds (Vis) were adopted in order to build proper classification models with a number of relevant advantages. At first, there exists the possibility to analyze the impact of independent variables on visibility with the consideration of its’ real variability. Secondly, through the application of the Monte Carlo method and the assumed classification algorithms, it was made possible to model the number of days during a precipitation and no-precipitation periods in a yearly cycle, on which the visibility ranged practically: Vis < 8; Vis = 8–12 km, Vis = 12–16 km, Vis = 16–20 km, Vis = 20–24 km, Vis = 24–28 km, Vis = 28–32 km, Vis > 32 km. The derived algorithm proved a particular role of precipitation and no-precipitation periods in shaping the air visibility phenomena. Higher visibility values and a lower number of days with increased visibility were found for the precipitation period contrary to no-precipitation one. The air quality index was lower for precipitation days, and moreover, strong, non-linear relationships were found between mortality and visibility, considering precipitation and seasonality effects.

The Visible: Element of the Social

In the context of a social-theoretical take on the link between social life and visibility, this paper invites to shift the focus from visibility phenomena to the visible. A theory of visibility, it is submitted, must be constructed as a theory of the medium. In opposition to visibility as a set of formal relations, what the visible brings to the fore is the existence of a mid term, a connective tissue. Also, if a theory is a prelude to a science, then a theory is needed that makes possible to measure the visible in itself. The development of an ‘intrinsic’ theory of the visible, one capable of generating its own variables and constants, along with the conceptual space for their articulation, is retrieved through the joint contributions of surface theories (Simmel, Goffman, Portmann) and intensity theories (Deleuze, Thom). The piece presents a set of notions that could be of use to analyse the fibre of the visible and the trajectories occurring in the visible, in view of laying out a series of laws of the visible.

Essay Review: Babylonian Astronomy and Celestial Divination: In the Path of the Moon: Babylonian Celestial Divination and its Legacy

study of Babylonian astronomy and celestial divination has a history that now extends over 140 years. It began with the publication by Henry Rawlinson and George Smith of Cuneiform inscriptions of Western Asia, iii (1870), Plates LI-LXIV, of which LXIII, Table of the movements of the planet VENUS and their influences, is none other than the Venus of Ammisaduqa. A number of these texts, including the Venus Tablet, were soon translated by Archibald Henry Sayee in astronomy and astrology of the Babylonians (1874), and a method of dating the Venus Tablet by dates of visibility phenomena in lunar months was described by Sayee and R. H. M. Bosanquet in The Venus Tablet (1880). next year J. Strassmaier and J. Epping published Zur Entzifferung der astronomischen Tafeln der Chaldaer ( 1881 ), containing descriptions of the various classes of texts and a decipherment of two columns of a lunar ephemeris (ACT 122, K-L), followed by Astronomisches aus Babylon (1889) and further papers (1890-95), with analyses of texts of mathematical and observational astronomy. These were followed by the first comprehensive studies by F. X. Kugler in Die Babylonische Mondrechnung (1900) and Sternkunde und Sterndienst in Babel (1907-35). During this period, there was also publication of texts of celestial divination, including C. Virolleaud's edition of the omen series Enuma Anu Enlil (1905-12) and the first of the many publications of E. Weidner. O. Neugebauer's Astronomical cuneiform texts (ACT, 1955) extended and greatly enlarged Kugler's work on mathematical astronomy through the publication of all known ephemerides, as the tabular mathematical texts are known, and procedure texts, rules for computation, with restoration of missing sections and systematic analysis of the methods of computation. And the same year A. Sach's Late Babylonian astronomical and related texts (LBAT, 1955) published copies of virtually all texts then known of mathematical and observational astronomy. These latter two publications have formed the foundation of research in these subjects ever since, most notably Neugebauer's analysis of the mathematical astronomy in A history of ancient mathematical astronomy (HAMA, 1975).

Low Visibility Formation and Forecasting on the Northern Coast of Brazil

Visibility analysis and forecast at the Maceio International Airport in the Brazilian Northeast (NEB) was the principal goal of this investigation. Surface meteorological data of the Maceio International Airport were used for low visibility frequency study. Low visibility in NEB was provoked more frequently by light fog (LF) formation (1,098 or 92 h month−1 on average). Haze and fog were very rare (81 h and one event per year, respectively on average). Light fog with a visibility less than 2 km usually was detected together with rain or drizzle. Low visibility was observed more frequently at night and during the rainy season. Applications of the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model for light fog forecast were tested. Thermodynamic processes were studied by vertical profile, elaborated by: (1) National Centers for Environmental Prediction (NCEP) reanalysis data for Maceio (because of some radiosonde absence) and (2) forecast vertical temperature and humidity profiles were produced, using Air Parcels Trajectories of the HYSPLIT model at the pattern levels. The synoptic situations before and during low visibility phenomena were analyzed using different products of NCEP reanalysis, the high resolution (10 km) ETA model and infrared satellite images. Wave disturbance in the trade winds field, localized on the northwest periphery of the South Atlantic subtropical High, usually accompanied the phenomena. A humidity advection, weak ascendant movement and thermal inversion absence at the low levels were created by these waves. The middle level’s descendent movement provoked the humidity accumulation at levels below. Satisfactory results of the HYSPLIT model applications for light fog forecast were obtained with 12 h antecedence. In particular, stable level forecast by the ETA model was forecast satisfactorily with 12 h antecedence; vertical movements were predicted better with up to 48 h antecedence. The PSU/NCAR mesoscale model (MM5) and PAFOG models were tested for analysis and forecast of an intensive fog event. Intensive fog provoked a fatal accident of a small airplane near the Maceio Airport in 2007. These fog formation processes were studied by NCEP reanalysis data, the high resolution regional model MM5, and satellite and radar data. Fog formation was simulated by PAFOG model and satisfactory results were obtained with 10 h antecedence.

Book Review: The Chronology of Old Babylon, Die Venustafeln des Ammī-⋅aduqa und ihre Bedeutung für die astronomische Datierung der altbabylonischen Zeit

THE CHRONOLOGY OF OLD BABYLON Die Venustafeln des Ammi-saduqa und ihre Bedeutung fur die astronomische Datierung der altbabylonischen Zeit. Joachim Mebert (Archiv fur Orientforschung Beiheft, xxxi; Berger & Sohne, Horn, 2010). Pp. 179. 38 (paperback). ISBN 3-900345-10-4.In 1912 F. X. Kugler discovered among omens on sixty-third tablet of Babylonian celestial omen series Enuma Anu Enlil a reference to Year of Golden Throne which he identified with eighth year of Old Babylonian king Ammi-saduqa. Tablet 63 of Enuma Anu Enlil contains a series of omens referring to dates of Venus's first visibility and first invisibility in morning and evening. Kugler suggested that, contrary to other tablets of Enuma Anu Enlil which contain pure omens, tablet 63 contains reports of observations which had been codified as omens. If this suggestion is correct, then Venus data on Enuma Anu Enlil tablet 63 (commonly referred to as the Venus Tablet of Ammi-saduqa) potentially provides means to establish date of reign of Ammi-saduqa and hence to provide a fixed point to pin floating, relative chronology of early second millennium b.c. known from king lists and other historical documents.Many attempts to date Venus Tablet of Ammi-saduqa have been made in hundred years since Kugler' s discovery. By middle of twentieth century, three possible chronologies had emerged: a high chronology in which Ammi-saduqa year 1 = -1710, a middle chronology with Ammi-saduqa year 1 = -1645, and a low chronology with Ammi-saduqa year 1 = -1581. Most Assyriologists and historians of ancient Near East have adopted middle chronology, but on no other grounds than that it is a convenient compromise and appears in all standard reference works. In recent years, several scientifically-trained scholars have argued in favour of other chronologies: P. J. Huber has made a forceful case for long chronology by combining evidence from Venus Tablet with eclipse omens from Enuma Anu Enlil tablets 20 and 21 which he believes refer to specific observations as well as month-length data taken from economic documents.1 V. G. Gurzadyan in a much criticized analysis has argued for a super-short chronology with Ammi-saduqa year 1 = -1549. 2 And most recently, T de Jong and V Foertmeyer have argued for Ammisaduqa year 1 = -1637 on basis of a possible connection with eruption of volcano on Thera.3The book under review presents a new and detailed study of Venus Tablet of Ammi-saduqa and its use in determining Old Babylonian chronology. Mebert begins by discussing Venus Tablet itself. It has long been recognized that tablet as it may be reconstructed from preserved copies is corrupt in various ways. Mebert provides a useful study of structure of tablet in order to extract a subset of omens which he believes are reliable. In order to investigate dates of Venus's visibility phenomena found in these omens, Mebert first investigates Late Babylonian observations of Venus in order to establish values for arcus visionis of phenomena of Venus for Babylon. He then uses these values to calculate dates of Venus's visibility during early second millennium b.c. which can then be compared with dates extracted from Venus Tablet. Next, Mebert compares preserved mo nth -length data from Old Babylonian period with calculated month lengths. By combining results from these two types of evidence, he concludes that most likely date for first year of Ammi-saduqa is -1573. Finally, Mebert investigates other evidence - most of it historical rather than astronomical - to see whether there are any contradictions with his proposed chronology and to provide supporting evidence of his proposed chronological equation. …

On the roles of circulation and aerosols in the decline of mist and dense fog in Europe over the last 30 years

Abstract. Fog and mist are meteorological phenomena that have significant contributions to temperature variations. Understanding and predicting them is also crucial for transportation risk management. It has been shown that low visibility phenomena over Europe have been declining over the past three decades. The trends in mist and haze have been correlated to atmospheric aerosol trends. However, dense fog has not received yet such focus. The goal of this paper is to examine the roles of synoptic atmospheric circulation and aerosol content on the trends of dense fog. We show that sulphur emission trends are spatially correlated with visibility trends, with a maximum correlation when visibility is between 1 km and 10 km. We find that atmospheric dynamics overall contributes up to 40% of the variability of the frequency of fog occurrences. This contribution is spatially variable and highly depends on the topography and the season, with higher values in the winter. The observed long-term circulation changes do not contribute much to the trends in low visibility found in the data. This process is illustrated on three stations (De Bilt, Zürich Airport and Potsdam) for which a long-term visibility data and a thorough meteorological description are available. We conclude that to properly represent fog in future climate simulations, it is necessary to include realistic representations of aerosol emissions and chemistry, land surface properties and atmospheric dynamics.

Visibility Phenomena with Interference by Multiple Reflections

Visibility Phenomena with Interference by Multiple Reflections