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Determination of the convective heat transfer coefficients from the surfaces of buildings within urban street canyonsSmith, James O. January 2010 (has links)
In the summer of 2007, the number of people living in the world’s urban areas exceeded that of those living in the countryside. Such urbanisation tends to modify the climates of towns and cities as a result of a number of factors which together form the ‘urban heat island’ effect. In order to better design buildings and urban areas to cope with these effects, it is first necessary to understand the heat transfer mechanisms which are taking place. The aim of the current research has therefore been to provide convective heat transfer data appropriate for low-rise urban environments by investigating the effects of wind speed, direction and street geometry. The research has employed the naphthalene sublimation technique which has been extended in several fundamental areas including development of a novel approach to measure the rate of sublimation from wind tunnel models. This technique has permitted measurements to be made over an array of discrete locations, revealing the variation across building surfaces. The uncertainty in the convective heat transfer coefficients obtained was calculated to be approximately ±6%. Tests were conducted in the BRE wind tunnel with an atmospheric boundary layer simulation appropriate to inner city areas. Cube models were arranged so as to form long rows of flat-roofed buildings referred to as ‘street canyons’. A series of correlations have been derived from the experimental results from which the rate of convection occurring from each building surface may be obtained with respect to wind speed. The greatest rates of convective heat transfer have been shown to occur at the top of the windward wall and leading edge of the roof, the lowest rates from the leeward wall of a building. Convection was found to be reduced in narrow street canyons. In wider street canyons, the convective coefficients on the exposed windward and roof surfaces of buildings were higher, but the values on the leeward wall are lessened due to the distancing of the downstream windward vortex. The effect of wind direction was found to be relatively small and therefore it is proposed that the convective heat transfer relationships presented may be applied irrespective of wind direction.
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The Urban Heat Islands Analysis : Factors of Building Surface, Green Area and LightingLiu, Hanyue, Liu, Qian January 2012 (has links)
Summary The development of urbanization and industrialization has improved the comfort level and the quality of human’s life effectively. But at the same time, it also caused many global environment problems, such as air pollution, greenhouse effect and urban heat island (UHI). The environment cannot keep the balance because of lots of industrial activities, anthropogenic heat and building surface effect. Almost 3 billion people, who are living in cities, have to face this situation, and the quantity is still increasing. The authors use literature research methodology, case study, comparative study and trend analysis study while writing. UHI have a harmful effect (such like photochemical smog and increasing energy use) on urban ecological environment, daily life and health. As the product of urbanization and industrialization, UHI has become one of the most important climate issues. Urban green space is helpful to reduce urban heat islands. London has a better urban green space system to face UHI and Hong Kong still has a long way to improve the green environment for reduce UHI. This article consider that roof greening is a suitable method to help Hong Kong gets rid of urban heat islands. And the lighting and population could indicate the level of urbanization, also can reflect the effect of urban heat islands preliminary. Over-capitalized lighting will exacerbate urban heat islands.
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Effect of frontal passage on 24-hour thermal variability of urban heat islandsWachter, Mary-Stewart 13 December 2019 (has links)
Building materials, lack of vegetation and absence of open spaces in urban areas cause surfaces such as asphalt to become warmer than nearby vegetated surfaces that surround the city, creating the urban heat island (UHI) effect. Little investigation has been done regarding temperature changes across these surfaces before and after frontal passages. This study analyzes the 24-hour temperature difference as a result of a cold front passage by examining the transitional seasons (Spring and Fall) for Dallas, Texas; Atlanta, Georgia; and Kansas City, Missouri. This research focused on investigating the pattern of moist and dry tropical air masses preceding a transitional air mass and moist and dry polar air masses the proceeding 24-hours. Using recorded hourly data from Automated Surface Observing Systems (ASOS) stations during these events one can visualize the time lag in temperature change between sites in developed urban areas and surrounding more vegetated surfaces outside the city.
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Análise das variações térmicas e higrométricas em Tapejara/PR: um estudo para o período de inverno / Analysis of thermal and hygrometric variations in Tapejara/PR: a study for the winter timeCalderon, Gabriela [UNESP] 18 November 2016 (has links)
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Previous issue date: 2016-11-18 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / A presente pesquisa foi realizada em Tapejara/PR, município de pequeno porte, localizado no noroeste do Estado do Paraná. O objetivo principal desta pesquisa foi analisar as diferenças de temperatura e umidade relativa do ar entre o campo e as áreas intraurbanas, com a finalidade de verificar a ocorrência de ilhas de calor. Para este estudo foi utilizado o método Sistema Clima Urbano proposto por Monteiro (1976), por meio do subsistema termodinâmico e as propostas metodológicas de Mendonça (1994), Amorim (2005) e Amorim, Dubreuil e Cardoso (2015). Foram instalados termohigrômetros digitais em pontos representativos da área intraurbana e rural para coleta dos dados de temperatura e umidade relativa do ar para a elaboração de painéis espaço temporais que demonstraram, de maneira bastante satisfatória, a ocorrência de ilhas de calor ou de frescor e ilhas secas ou úmidas. A temperatura do ar foi registrada ainda por meio de transectos móveis para a realização da modelagem da ilha de calor urbana. A análise dos elementos meteorológicos foi realizada para os meses de julho e agosto de 2014, considerando-se as características geoambientais e geourbanas, tais como, materiais construtivos, presença de vegetação arbórea, uso e ocupação da terra e características do relevo. Os resultados mostraram diferenças importantes nestes elementos, caracterizando a formação de microclimas próprios, e a existência de ilhas de calor urbana com intensidade que chegou a 6,5°C e ilhas secas de até -23% no período analisado, em relação aos dados coletados na área rural. / This research was conducted in Tapejara / PR, a small city located in the northwest of Parana State. The main objective of this research was to analyze the differences in temperature and relative humidity between the field and intra-urban areas, in order to verify the occurrence of heat islands. For this essay we used the proposed method of Urban Climate System, by Monteiro (1976), by means of thermodynamic subsystem and methodological approaches of Mendonça (1994), Amorim (2005) and Amorim, Dubreuil and Cardoso (2015). There were installed digital thermohygrometer in representative points of intra-urban and rural area for data gathering of temperature and relative humidity for the development of temporal space panels have demonstrated, fairly well, the occurrence of heat islands or freshness and dry islands or damp. The air temperature was also recorded by mobile transects to perform the modeling of urban heat island. The analysis of the meteorological elements was performed for the months of July and August 2014, considering the geoenvironmental and geourbanas characteristics, such as building materials, presence of arboreal vegetation, use and occupation of land and relief characteristics. The results showed important differences in these elements, marking the formation of own microclimates, and the existence of urban heat islands with intensity reaching 6,5ºC and dry slands up to -23% in the analyzed period, in relation to the data collected in the rural area. / CNPq: 134208/2014-5
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Do mice in Columbus, compared to the surrounding areas, follow Bergmann’s rule?Blanton, Natalie J. 05 May 2021 (has links)
No description available.
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O clima urbano de cidades de pequeno porte do oeste paulista : análise do perfil térmico de Presidente Venceslau, Santo Anastácio e Álvares Machado, Brasil /Teixeira, Danielle Cardozo Frasca. January 2019 (has links)
Orientador: Margarete Cristiane de Costa Trindade Amorim / Resumo: A investigação da interferência da cidade na composição da atmosfera próxima à superfície remonta ao século XIX. Os estudos pioneiros do clima urbano apresentaram considerações sobre as alterações da cidade e da agricultura nos climas dos lugares. Esse quadro de interferências gerou grande comprometimento da qualidade do ambiente, refletindo nas condições de vida das populações, pois as alterações climáticas influenciam no conforto térmico, na saúde e no desempenho humano. Especialmente no ambiente tropical, o desconforto térmico demanda adaptação via climatização dos ambientes internos, influenciando no maior aporte energético, além de não ser acessível por parte da população. Em contrapartida, os espaços externos estão sujeitos aos efeitos das ilhas de calor, derivadas das condições meteorológicas e das características urbanas (OKE, 1987). O clima urbano é entendido como o clima de um determinado espaço e sua urbanização (MONTEIRO, 1976), não existindo uma escala rígida para o diagnóstico deste fenômeno. Nesse sentido, as cidades médias e pequenas também mostram importantes alterações das suas condições pretéritas à urbanização e exibem relativas facilidades para uma investigação climática qualitativa, pois seus espaços reduzidos permitem a melhor diferenciação dos seus ambientes intraurbanos e existem possibilidades de intervenção e planejamento urbano nos novos espaços em expansão. Esta pesquisa teve como objetivo investigar o clima urbano de cidades do ambiente tropical ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The investigation of cities’ interference in the composition of the near-surface atmosphere dates back to the nineteenth century. Pioneering studies on the urban climate presented considerations regarding changes in cities and agriculture in the climates of the places. This situation of interference compromised to a large degree the quality of the environment, reflecting on the living conditions of the populations, as climate change has an impact on human thermal comfort, health, and performance. Particularly in the tropical environment, thermal discomfort demands adaptation via climate control of indoor environments, influencing the greater energy supply, besides not being accessible by the population. In contrast, outdoor spaces are subject to the effects of heat islands, derived from weather conditions and urban characteristics (OKE, 1987). The urban climate is understood as the climate of a given space and its urbanization (MONTEIRO, 1976), and there is no rigid scale for the diagnosis of this phenomenon. In this sense, small and medium-sized cities also show important changes in their conditions prior to urbanization and present relative ease for a qualitative climate investigation, as their small spaces allow a better differentiation of their intraurban environments, and there are possibilities of intervention and urban planning in the new expanding spaces. This research aimed to investigate the urban climate of cities in the tropical environment located in the western ... (Complete abstract click electronic access below) / Doutor
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A remote sensing analysis of residential land use, forest canopy distribution, and surface heat island formation in the Atlanta Metropolitan RegionStone, Brian, Jr. 05 1900 (has links)
No description available.
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Relação entre ilhas de calor urbano e mudanças no uso da terra: um estudo de caso para Londrina - PR.COSTA, Ewerton Vôlney da Silva. 15 May 2018 (has links)
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Previous issue date: 2015-08-27 / Capes / O crescimento desenfreado das cidades é um problema decorrente do aumento da
população, causando inúmeras complicações para a sociedade e meio ambiente, como por exemplo, poluição, assoreamento de rios, desmatamento, alterações no clima local ou regional. O aumento da temperatura está diretamente ligado ao crescimento urbano, sendo influenciado pelo alto índice de construções, poluição, redução da vegetação e impermeabilização do solo, ocasionando problemas para a saúde dos habitantes e um desconforto térmico, gerando as chamadas ilhas de calor urbano (ICU). O estudo tem como objetivo identificar áreas propícias para a formação das ICU, caracterizar as mudanças do uso e ocupação do solo sobre a temperatura, estimar o saldo de radiação e os índices de vegetação (NDVI), água (NDWI) e área construída (NDBI) no período entre 1985 e 2007 em Londrina/PR. Foram gerados diagramas de dispersão com o intuito de analisar as relações entre os índices e a temperatura. Durante esse período, a vegetação e as áreas de solo exposto perderam espaço para a malha urbana, que apresentou um crescimento superior a 17%. A temperatura mínima encontrada na zona urbana com o passar dos anos fica cada vez mais elevada, em 1985 apresentou 22,4°C, já em 2007 apresentou 26,3°C, um aumento de aproximadamente 4°C. A temperatura na malha urbana também se apresentou mais elevada em comparação com as outras classes, chegando a marcar mais de 8°C em comparação com a vegetação densa. As temperaturas mais altas se apresentam nas regiões de solo exposto, estradas e alta densidade de edificações e as menores temperaturas foram identificadas nos corpos hídricos. A relação entre temperatura e os índices, indicou que quanto maior a temperatura, menor os valores de NDVI e NDWI. Já o NDBI, apresentou valores maiores à medida que a temperatura aumenta. / The rampant growth of cities is a problem due to increased population, causing
numerous complications for society and the environment, such as pollution, silting of
rivers, deforestation, changes in local or regional climate. The temperature rise is
directly linked to urban growth, being influenced by the high number of buildings,
pollution, reduction of vegetation and soil sealing, causing problems for the health of
inhabitants and thermal discomfort, generating the so-called urban heat islands (ICU ).
The study aims to identify areas suitable for the formation of the ICU, to characterize
the changes of land use and occupation over temperature, estimate the net radiation and
the vegetation index (NDVI), water (NDWI) and building area (NDBI ) between 1985
and 2007 in Londrina / PR. Scatter plots were generated in order to analyze the
relationship between the indexes and the temperature. During this period, vegetation and bare soil areas lost space to the urban fabric, which showed a growth of 17%. The minimum temperature found in the urban area over the years becomes increasingly higher in 1985 showed 22.4 ° C in 2007 showed 26.3 ° C, an increase of about 4 ° C. The temperature in the urban also showed the highest in comparison with the other classes, reaching scores more than 8 ° C as compared with dense vegetation. The higher temperatures present in the soil exposed areas, roads and buildings high density and lower temperatures have been identified in water bodies. The relationship between temperature and indices indicated that the higher the temperature, the lower the NDVI values and NDWI. Since the NDBI, had larger values as the temperature increases.
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Os efeitos de áreas agrícolas urbanas na intensidade das ilhas de calor em Florianópolis - SC /Silva, Gustavo Henrique Pereira da. January 2020 (has links)
Orientador: Margarete Cristiane de Costa Trindade Amorim / Resumo: O acelerado crescimento das cidades associado a um planejamento ineficiente ocasionou inúmeros problemas ambientais que recaem sobre a qualidade de vida da população. Nesse contexto de alterações das condições do ambiente natural, inúmeros estudos científicos foram suscitados, dentre eles, destacam-se os que se propuseram a estudar o clima das cidades. Diante disso, esta pesquisa baseou-se na proposta teórica e metodológica do Sistema Clima Urbano (S.C.U), com enfoque no subsistema termodinâmico e teve como objetivo central investigar os efeitos de áreas agrícolas urbanas na intensidade das ilhas de calor em Florianópolis - SC, no que se refere às condições de temperatura, um dos principais elementos climáticos responsáveis pelo conforto térmico. A ênfase dada à Florianópolis relaciona-se à presença de um marco legal que prevê a implantação e apoio à prática agrícola nos espaços intraurbano e periurbano. Os procedimentos metodológicos realizados, consistiram na busca por dados de temperatura a partir de técnicas de sensoriamento remoto e pontos fixos. Foram tratadas e analisadas as imagens do satélite Landsat-8, que mostraram diferenças nas características térmicas dos alvos, comparando-se áreas densamente construídas com áreas não construídas, apresentando intensidades de ilhas de calor de superfície de até 14ºC. As áreas com maior desenvolvimento vegetativo, com destaque para aquelas localizadas nos topos dos morros, apresentaram as menores temperaturas das cenas e as áreas... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The accelerated growth of cities associated with inefficient planning has caused numerous environmental issues that affect the population quality of life. In this context of changes in natural environment conditions, several scientific studies have been carried out, among which stand out those who focused on studying the climate of cities. Therefore, the present research was based on the theoretical and methodological proposal of the Urban Climate System (UCS), with emphasis on the thermodynamic subsystem. The main objective was to investigate the effects of urban agricultural areas on the intensity of heat islands in Florianópolis - SC, with regard to temperature conditions, one of the main climatic elements responsible for thermal comfort. The emphasis given to Florianópolis is related to the presence of a legal framework that provides for the implementation and support of agricultural practice in intra-urban and peri-urban spaces. The methodological procedures performed consisted of researching temperature data using remote sensing techniques and fixed points. Landsat-8 satellite images were treated and analyzed, which presented differences in the thermal characteristics of the targets, comparing densely built areas with non-built spaces, revealing intensities of surface heat islands of up to 14ºC. The areas with the highest vegetative development, with emphasis on those located at the top of hills, presented the lowest temperatures in the scenes, and the areas of urban an... (Complete abstract click electronic access below) / Mestre
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As ilhas de calor urbanas em Jundiaí-SP /Dorigon, Larissa Piffer. January 2019 (has links)
Orientador: Margarete Cristiane de Costa Trindade Amorim / Resumo: Nesta pesquisa levantou-se a hipótese de que conhecer o campo térmico de Jundiaí e saber a forma e intensidade das ilhas de calor urbanas resulta em informações relevantes a serem inseridas nas ações de planejamento. Acredita-se ainda, que a utilização da metodologia das Zonas Climáticas Locais (LCZs) facilita a comparação dos resultados obtidos em Jundiaí com outras áreas urbanas, uma vez que esta proporciona a uniformização e padronização de terminologias referentes aos usos e ocupações da terra. Para tanto, o objetivo principal foi diagnosticar o campo térmico da cidade de Jundiaí/SP e elaborar uma análise síntese, apresentando as intensidades de ilhas de calor em relação às características de superfície. Para atingir os objetivos propostos as pesquisas de campo ocorreram através da instalação de 10 sensores fixos que registraram dados horários de temperatura entre abril e dezembro de 2017 e realizados 10 episódios de levantamento com medidas itinerantes em agosto e setembro do mesmo ano. Os dados fixos identificaram que a maior expressão das ilhas de calor esteve conectada com uma sequência de estabilidade atmosférica. As maiores intensidades das ilhas de calor foram registradas, predominantemente, nos meses com as menores precipitações totais (junho, julho, agosto e setembro), enquanto no ciclo diário, as maiores intensidades foram noturnas. Notou-se também que, predominantemente, as maiores intensidades estiveram relacionadas com LCZs características de áreas urbana, LC... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In this research it was hypothesized that knowing the thermal field of Jundiaí and knowing the distribution and intensity of urban heat islands results in relevant information to be included in the planning actions. It is also believed that the use of the Local Climate Zones (LCZs) methodology facilitates the comparison of the results obtained in Jundiaí with other urban areas, since it provides the standardization and standardization of land use and occupation terminology. Therefore, the main objective was to diagnose the thermal field of the city of Jundiaí/SP and to elaborate a synthesis analysis, presenting the urban heat island intensities in relation to the surface characteristics. In order to achieve the proposed objectives, the field research was carried out by installing 10 fixed sensors that recorded hourly temperature data between April and December 2017 and carried out 10 episodes of itinerant survey in August and September of the same year. Data from fixed sensors identified that the highest expression of heat islands was connected with an atmospheric stability sequence. The highest intensities of the urban heat islands were predominantly recorded in the months with the lowest total of rainfall (June, July, August and September), while in the daily cycle the highest intensities were nocturnal. It was also noted that, predominantly, the highest intensities were related to LCZs characteristic of urban areas, LCZ 3, LCZ 3B, LCZ 34 and LCZ 7, all compact and with lit... (Complete abstract click electronic access below) / Doutor
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