As a part of the European research program CAL, sprite observations were carried out from the OMP observatory in the French Pyrenees during the summer 2003. Images of the sprites were taken by two remotely controlled CCD cameras. The 23 July was considered particularly interesting because we then had access to data concerning both cloud-to-ground and intracloud lightning activity. This day was therefore chosen as the object of the present study. A large thunderstorm with two convective cores, one to the north and the other to the south, developed over the South of France during the late afternoon, and about two hours after sunset, the first sprite was detected. During a little more than three hours, 13 sprites were observed, 7 over the northern system and 6 over the southern system. The images enabled us to determine the azimuth angle of each sprite from the OMP observatory. 12 of the 13 sprites could be associated to positive cloud-to-ground flashes, and by putting together the sprite directions and the locations of the associated flashes on the radar images, we managed to get a rough idea of the position of the sprites in the storm system, and also to estimate their vertical and horizontal extent. Satellite images were included at this point of the study, and it appeared clear that sprites tend to occur over the stratiform region of the storm system in the area with the coldest (highest) cloud tops. The associated positive flashes were also within or close to this portion of the storm. The sprite occurrences were studied in relation to the cloud-to-ground and to the intracloud activity. We found that sprites seem to occur in a late stage of each storm system, when the rate of negative cloud-to-ground flashes has considerably decreased, and when the ratio of positive cloud-to-ground flashes is much higher then during the most active phase of the storm. Globally, the intracloud activity is also low during the sprite-producing periods, but sudden "bursts" of intracloud lightning could frequently be observed at the moment of the sprite. The peak current of the positive flashes was found to be rather weakly correlated to their sprite-generating capacity. The available Schumann resonance measurements seem to indicate that the charge moment is a much more adequate parameter in this respect. The areal coverage of the radar echo was calculated. The result supports the idea that sprite events tend to appear almost exclusively over large thunderstorm systems.

Sprites, halos, and elves are members of a family of short-lived, luminous phenomena known as Transient Luminous Events (TLEs), which occur in the middle atmosphere. Sprites are vertical glows occurring at altitudes typically ranging from ~40 to 90 km. In video imagery they exhibit a red color at their top, with blue tendril-like structure at low altitudes. Elves are disk-like glows that occur at the base of the ionosphere, with diameters of ~100-300 km, and have very short lifetimes (~2-3 ms). Halos are diffuse glows that occur at low altitudes, have diameters <100 >km, and have a duration that may last up to 10s of ms. A majority of the studies of TLEs have taken place over the Midwestern U.S. where they were first discovered. This area produces large thunderstorms, which in turn generate large lightning discharges that have been associated with the formation of TLEs. Studies have used the low frequency radiation that initiates with these strokes to study characteristics of these events. This low frequency radiation has been used to determine where large numbers of TLEs may occur. Extreme southern Brazil is a region of the globe believed to have many TLEs, but few studies on these phenomena. Two collaborative campaigns involving Utah State University proceeded in 2002- 2003, and in 2006. Multiple TLE images were made, proving this is, indeed, a region of the globe where these types of events are prominent. In particular, one storm in February 2003 produced over 440 TLEs imaged by USU video cameras. Of these events, over 100 of them had associated halos. Statistical studies for halos previously had been performed in the U.S., but never abroad. Also, several events from the February storm have been associated with negative cloud to ground lightning, a surprising occurrence, as to date, less than a handful of such events have ever been witnessed or published. In analyzing the TLEs from this campaign, we have shown the halos are similar to those seen in the U.S., even though the storms may be somewhat different. Also, detailed analyses of the negative events show both temporal and spatial morphology heretofore never reported on.

The objective of this study is to investigate the interaction between a lightning strike and carbon/fiber composites. The first approach is to characterize the damage development in a composite structure subjected to simulated lightning strikes. Several existing studies have acknowledged that the lightning induced damaged can be categorized into two separate domains of damage; a primary domain of damage that occurs at the attachment point, and a secondary domain of damage that is typically formed around the attachment point. Quantitative studies of the causes of the primary damage domain are not satisfactory for explaining the secondary damage domain and thus, these two domains are produced by presumably different mechanisms. There have been many reports and studies focused on the inspection of the primary damaged area. However, the secondary domain of damage has not yet been fully explained and understood. An experimental setup was configured with a recommissioned lightning current simulator to generate artificial lightning strikes consistent with the existing standard for lightning protection testing used in the aerospace industry. Carbon/epoxy composite laminates in various layups and Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) panels were subjected to high impulse currents of different magnitudes. The lightning induced damage to the protected and non-protected composite laminates and PRSEUS panels were evaluated, and the influence of different variables such as current magnitude, strike location, and laminate layup were studied. An interesting observation was the secondary damage area that expanded laterally beyond the intense damage area. The structure of a composite panel is such that it forces the current to flow along the carbon fibers directions, as opposed to metals where the relatively isotropic conductivity of the metal allows current to distribute radially. It is argued in this work that the secondary domain of damage may be related to the anisotropic electrical conductivity property of the composite panels. A comprehensive theory based on multidimensional electromagnetic field simulation was proposed to reveal the root cause mechanisms of the unique patterns of secondary damage in the carbon composite structural materials tested with simulated lightning current impulses.

The maximum number of thunderstorms in the United States occur in Central Florida. The cloud-ground lightning from these storms is responsible for extensive damage to life and property. The lightning from these storms is also responsible for delays and cancellations of space shuttle launch attempts at the Kennedy Space Center (KSC) and the 45th Space Wing unmanned launches at Cape Canaveral launch facilities. For these and other reasons accurate forecasting of cloud-ground lightning is of crucial importance. The second phase of NASA's Tropical Rainfall Measuring Mission Texas and Florida Underflights project (TEFLUN-B) was conducted between 1st August and 30th September, 1998. The S-band dual-polarization radar (S-Pol) belonging to the National Center for Atmospheric Research (NCAR) was part of the surface based facilities during this project, and was located at Melbourne, Florida. This provided an excellent opportunity to observe Florida thunderstorms with the help of a dual-polarization radar. This project aims at developing cloud-ground lightning forecasting signatures by analyzing S-Pol data for 10 thunderstorms that occurred over the Kennedy Space Center. Time-height trends of reflectivity, ice and graupel-hail as well as electric potential trends for these storms are taken into consideration while developing the forecasting signatures. This thesis proposes that a 35dBZ echo at the -5[degree]C temperature level is the best indicator of imminent CG lightning with a POD of 90%, an FAR of 10% and a CSI of 81.8%. An electric potential level of approximately 1000 V/m also indicates the onset of cloud-ground lightning. An analysis of the microphysical structure of the thunderstorms reveals that the presence of graupel-hail at the -10[degree]C temperature level is necessary in order for cloud-ground lightning to occur.

Many people may feel insecure if a place or an area have poor lightning. When darkness falls, it is a natural reaction to become cautious as control over seeing one's surroundings deteriorates. People are very dependent on lighting in urban environments. If the environments do not have enough lighting, limitations for the individual may arise from the fear of being exposed to a threatening situation. The purpose of this study is to analyze how young adults experience the lighting in Umeå's central city, from a safety perspective. The study also focuses on what improvements regarding lighting there are in Umeå according to the interviewees that they believe can increase their safety in an area. The study is based on 6 interviews with 3 men and 3 women between the ages of 20 - 30 who live in the Umeå regional center. In order to investigate the purpose further, coding of the collected interview material has also been done. After analyzing the material, it emerged that women's insecurity is based on the fear of being exposed to abuse or a threatening situation. While the men were more afraid of the dark due to poor visibility or the fear of being jumped on by an animal. There were also many suggestions for improvement opportunities regarding lighting in Umeå.

The protection zone of the Franklin Rod is widely used in practice due to its effectiveness and the wide usage. The theories are based on the mathematical approaches, regardless of physical inherence of lightning strokes. The study of this thesis is based on computer analysis of the field distribution in pre-breakdown stage, laboratory experiments of various test configurations and mathematical modeling. The impact of the Franklin Rod¡¯s height and the polarity of impulse are considered. New equations are developed to calculate the striking distance to Franklin Rod both under negative and positive polarity lightning strokes. The lightning protection zone of the Franklin Rod can be predicted by a proposed elliptical model. The experimental data coincides to the calculated protection zone by proposed equations. Finally, the dual-rod lightning protection system is studied. The protection zone of the dual-rod protection system can be evaluated by a combination of Rolling Sphere Circular Model and elliptical model.

Denna uppsats är ett examensarbete på 22,5 Hp, gjort av Natalie Pålsson, student på produktdesignprogrammet på Malmö Högskola, under våren 2013.Projektet handlade om att undersöka möjligheten till att skapa en ljuskälla utan elektricitet. Syftet med projektet var att uppmärksamma problematiken av den höga energiförbrukningen av ljuskällorna i belysning. Projektet hade under hela dess gång ett biomimetiskt förhållningssätt och under förstudien gjordes en grundlig studie av ämnet biomimetik. Biomimetik innebär att man som designer lär och inspireras av naturen i sin produktutveckling. Förstudien behandlade även ämnet naturens ljus och då framför allt bioluminiscens som valdes som ljuskälla i armaturen. Utifrån en intervju med Lars Olof Björn, pensionerad professor i biologi, så togs ett beslut att använda levande organismer i armaturen eftersom bioluminiscens är svårt att framställa på kemisk väg. Under studierna av bioluminiscens så framkom det att det finns en bioluminiscent alg, dinoflagellat som skulle vara lämplig att använda som ljuskälla. Dinoflagellater avger ett bioluminiscent ljus då de sätts i rörelse, vilket användes som en sorts strömbrytare i produkten. Resultatet blev lyktan Lumi oh! En lykta, utformad som ett timglas som ser ut som två droppar som i sitt möte bildar en virvel. När lyktan vänds upp och ner, virvlar algerna ner och börjar då lysa, vilket de gör så länge de är satta i rörelse.Projektets mål var att det skulle resultera i ett produktkoncept, därför presenteras slutresultatet i form av en utseendemodell. / This diploma work (22,5 ECTS) at bachelor level is made by Natalie Pålsson, student at the Product design program at Malmö University, in the spring of 2013. The project explored the possibility of creating light without electricity. The purpose of the project was to highlight the problem of the high energy consumption of our current lightsourses. The project had a biomimetic approach and a thourough study of the subject was made. Biomimicry means that designers learn and get inspired by nature in their development of products. A study about natural light was made, especially bioluminescence, since that was the choice of lightsource. Based on an interview with Lars Olof Björn, a retired proffessor in Biology, it was decided to use living organisms in the lantern, since bioluminescence is difficult to produce chemically. The research regarding bioluminescence showed that there is a bioluminescent algae, called dinoflagellate, that would be suitable for use as a light source. Dinoflagellates emit a bioluminescent light when they are put in motion, which was used as a sort of on and off switch in the product. The project resulted in the lantern Lumi oh! A lantern, shaped like an hour glass which looks like two drops, that forms a swirl where they meet. When the lantern is turned upside down, the alge swirls down and starts to glow, for as long as they are set in motion. The result of the project was to be illustrated as a product concept and is presented as a prototype that shows the form but not the function.

Recent severe weather research has examined the potential role of total lightning patterns in the severe thunderstorm warning-decision process although none to-date have examined these patterns in explicitly weak-shear environments. Total lightning flashes detected by the Earth Networks Total Lightning Network (ENTLN) during the 2012-13 convective seasons (1 May – 31 August) over a region of the Central Appalachian Mountains were clustered into likely discrete thunderstorms and subsequently classified as either single-cell or multicell/supercell storm modes. The classification of storms was determined using a storm index (SI) which was informed by current National Weather Service (NWS) identification techniques. The 36 days meeting the minimum threshold of lightning activity were divided into 24 lightning-defined (LD) single-cell thunderstorm days and 12 LD multicell/supercell days. LD single-cell days possessed statistically significant lower 0000 UTC 0-6 km wind shear (13.8 knots) than LD multicell/supercell days (26.5 knots) consistent with traditional expectations of single-cell and multicell/supercell environments respectively. The popular 2σ total lightning jump algorithm was applied to all flashes associated with 470 individual LD thunderstorms. The frequencies of the storms’ total lightning jumps were then compared against any associated severe weather reports as an accuracy assessment. The overall performance of the algorithm among both categories was much poorer than in previous studies. While probability of detections (POD) of the 2σ algorithm were comparable to previous research, false alarm rates (FAR) were much greater than previously documented. Given these results, the 2σ algorithm does not appear fit for operational use in a weak shear environment. / Master of Science

As descargas atmosféricas sempre foram tratadas como acontecimentos fortuitos e de força maior, inerentes à vontade do homem. Contudo, mudanças significativas a esse respeito ocorreram recentemente na legislação brasileira, no Código Civil e na norma ABNT NBR 5410: 2004 (Instalações Elétricas de Baixa Tensão). Além disso, em 29 de abril de 2004 foi publicada a Resolução Normativa nº 61 da ANEEL, que estabelece as disposições relativas ao ressarcimento de danos, em equipamentos elétricos instalados em unidades consumidoras, causados por perturbações no sistema elétrico. De acordo com essa nova visão, as descargas atmosféricas devem ser tratadas como fenômenos que podem ter as suas conseqüências previstas, evitadas ou ao menos minimizadas, fazendo com que os custos associados não sejam considerados simplesmente como prejuízos, mas sim passíveis de ressarcimento junto à concessionária. Tais fatores, aliados à inexistência de uma metodologia comum para análise dos prejuízos causados por esse fenômeno, motivaram a realização deste trabalho, que teve por objetivo avaliar os custos decorrentes de descargas atmosféricas em sistemas de distribuição de energia. Além de aspectos técnicos e jurídicos, são discutidos os custos referentes à energia não fornecida, danos em equipamentos, mão-de-obra e ressarcimento de pedidos de indenização por danos (PIDs). Discute-se ainda, embora de forma superficial, a importância de contabilização do custo da imagem da empresa junto aos consumidores. Finalmente, apresenta-se uma metodologia para determinação de tais custos, a qual é aplicada a casos reais, com comparação e análise dos resultados obtidos em diferentes situações. / Lightning discharges have always been treated as Acts of God and force majure events, inherent to man?s will. However, significant changes to this regard have recently occurred in the Brazilian Law, in the Civil Code and on the Brazilian Standard ABNT NBR 5410: 2004 (Low Voltage Electric Installations). In addition, on April 29th, 2004, ANEEL Normative Resolution No. 61 was published, which establishes the provisions regarding reimbursement of damages in electrical equipment installed in consumer units, caused by disturbances in the electrical system. According to this new version, the lightning discharges must be treated as phenomena which may have their consequences foreseen, avoided or at least minimized, causing the associated costs to be considered not only as losses, but also entitled to reimbursement with the operator. Such factors, allied to the non-existence of a common methodology for the review of the losses caused by such phenomenon, motivated the development of this work, which aimed at assessing the lightning-related costs in power distribution systems. In addition to the technical and legal aspects, the costs regarding non-supplied power, equipment damage, labor and indemnity claims (PIDs), are also discussed. Although superficially, the importance of taking into account the cost of the company?s image with the consumers is also discussed. Finally, a methodology for the determination of such costs is presented and applied to actual cases, with comparison and analysis of the results obtained in different situations.

A universalização da energia elétrica, como uma das principais políticas públicas de inclusão social, tem como desafio a escolha de alternativas tecnológicas capazes de conciliar os aspectos de viabilidade técnica e econômica. A Tecnologia cabos para-raios energizados (PRE), objeto de estudo desta tese, se insere neste contexto. Assim, este trabalho consiste na análise de viabilidade do PRE no esquema trifásico, cuja instalação é associada à linha de transmissão 230 kV do sistema de transmissão de Rondônia. São analisados os aspectos de seu desempenho técnico, operacional e econômico. No aspecto técnico é analisado o desempenho do sistema de aterramento quanto à resistência de terra, tensões de toque e de passo, além de análise da queda de tensão, desequilíbrio de tensão e capacidade de carregamento da instalação. A abordagem técnica é aprofundada após análise do desempenho operacional avaliado a partir da classificação das interrupções verificadas em mais de 180 meses de operação do Sistema PRE Rondônia. Em decorrência dessa avaliação, são obtidos índices operacionais de continuidade, analisados comparativamente em relação a outras alternativas tecnológicas, visando analisar a viabilidade da Tecnologia PRE. Uma das constatações resultantes da análise das causas das interrupções indica um elevado impacto das descargas atmosféricas no desempenho do PRE. Este aspecto é extensivamente analisado quanto aos efeitos das descargas diretas e indiretas sobre a instalação, partindo-se de medições de campo nos contrapesos das torres, medições de resistividade do solo e ensaios na cadeia de isoladores do PRE. Simulações são realizadas utilizando-se os programas computacionais ATPDraw, ERM e CDEGS para análise das tensões resultantes de descargas diretas, tensões induzidas por descargas indiretas e cálculo de resistência de terra, respectivamente. São investigados os efeitos de parâmetros importantes no desempenho do sistema frente a descargas atmosféricas e comparados os números de interrupções estimadas e verificadas em campo, partindo-se de um roteiro metodológico minuciosamente detalhado, a fim de permitir a repetição dos procedimentos em situações semelhantes às analisadas neste trabalho. Após uma análise comparativa do desempenho do sistema PRE em relação a outras alternativas convencionais, são estabelecidos índices de referência para o desempenho operacional da Tecnologia PRE e desenvolvida uma análise econômica da implantação dessa tecnologia em Rondônia. / As one of the major public policies of social inclusion, the universalization of electric energy services has as a challenge to choose appropriate technological solutions that combine technical and economic aspects. The energized shield wire line technology (SWL), subject of this thesis, is in this context. This study aims at evaluating the viability of the SWL technology (three-phase scheme) installed on a 230 kV transmission line in the State of Rondônia. The analysis covers its technical, operational, and economic performance. The former aspect considers the performance of the grounding system regarding the ground resistance and step and touch voltages, analysis of voltage drop, voltage unbalance and the load capacity of the installation. The technical issue is deeply held after the analysis of the system operational performance in Rondônia based on the classification of outages considering a period greater than 180 months. The operational indices that result from this evaluation are compared to those corresponding to other technology alternatives in order to evaluate the viability of SWL technology. The analysis of the causes of interruptions reveals that lightning has a significant impact on the SWL performance. Thus, an extensive analysis is carried out regarding the effects of direct and indirect strokes on the SWL, including field measurements (soil resistivity and tower footing resistance) and laboratory tests (determination of the positive and negative critical flashover overvoltages of insulator strings). Simulations are performed using computer programs of proved validity (ATPDraw, ERM, and CDEGS) for the analysis of lightning overvoltages resulting from direct and indirect strokes and for the calculation of ground resistance. The effects of important parameters on the system lightning performance are investigated and the estimated and observed frequencies of interruptions are compared. The applied methodological procedure is described in detail, to allow the method to be used in other cases similar to the situations examined on this study. After a comparative analysis of the performance of the SWL with respect to other conventional alternatives, reference indices for the operational performance of SWL Technology are set and an economic analysis of the SWL technology in Rondônia is carried out.