External Meteorological Conditions Research Articles

Mathematical modeling of environmental conditions inside historical buildings. The case of the archaeological museum of Athens

Indoor pollutants can damage cultural property stored in museums, art galleries, libraries and archives. A relatively small number of measurements available for the interiors are restricted to just a few gases. The paper draws attention to the lack of information about the airborne pollutants' dispersion of museum interiors and presents a mathematical model, implemented in a general computer code, that can provide detailed information on velocity and temperature as well as pollutants' concentrations prevailing in three-dimensional buildings of any geometrical complexity, for given external meteorological conditions. The model involves the partial differential equations governing flow and heat transfer, in large enclosures, containing heat and pollutants sources. Turbulent flow is simulated and buoyancy effects are taken into account. The model allows for such practical aspects of the problems under consideration as blockages, internal heat and contaminants loads, external weather conditions, the presence of people, etc. The model is used to assess the environmental conditions inside the main Hall of the National Archaeological Museum of Athens (Myceane Hall) with external conditions corresponding to Ministry of Environment summer and winter days.

The broadband seismic station CAD (Túnel del cadí, eastern pyrenees): Site characteristics and background noise

Abstract This article presents the main characteristics of the broadband (BB) seismic station of Túnel del Cadí (CAD) along with an analysis of seismic noise and its correlation with regional meteorological conditions. The quality of the sensor site (in a closed cave, 80 m below surface) provides ideal conditions for the location of a BB station with the ability to detect small events. Through the analysis of noise series 30 min in length during a period of 15 months, a characterization of the level of detectability has been performed. Using one estimate of noise per day, the seasonal variation of the amplitude of the noise has been analyzed, and using four samples per day, short-period variations have been studied and compared with external meteorological conditions. Results show that the characteristics of the station are similar to a typical station placed in a hard basement rock and that there are no differences between the behavior of the three components. The analysis of several spectral components shows the relative excitation of microseisms and atmospheric disturbances that may differ more than one order of magnitude. There is a clear anticorrelation between the noise amplitude spectra and the atmospheric pressure in short-period variations, and the high-frequency noise is directly related to the external wind velocity, although there is not a direct impact to the sensor site. No correlation of the shape of the spectra (general or for specific frequencies) with any meteorological parameter is observed.

Design wind loads for closed farm buildings

Efficient design of buildings requires a detailed knowledge of the loads the building will be subjected to in the course of its life. These loads consist of those induced by external meteorological conditions, such as wind and snow, together with building usage loads and service loads. This paper is concerned with wind load and the recently revised procedures for assessing wind loads for agricultural buildings. Wind loads are now assessed statistically in accordance with the British Standard Institution Code of Practice, CP3: Chapter V: Part 2. The application to farm buildings of this Code of Practice is discussed. Full-scale measurements have been made of wind loads on agricultural buildings and show the procedures of CP3: Chapter V: Part 2 to be appropriate. However, the detailed information in the Code of Practice is shown to be in need of revision and augmentation by the incorporation of wind loads for additional building geometric parameters.

A Lake Breeze on the Eastern Shore of Lake Michigan: Observations and Model

This study was undertaken to determine the physical and dynamical characteristics of the lake breeze wind system at a site on the eastern shore of Lake Michigan. Lake breeze development and progress inland were observed by hourly pilot balloon ascents in a vertical plane perpendicular to the lake shore. The fields of moisture and temperature in this vertical plane on a day when a clearly defined lake breeze occurred were obtained using an instrumented aircraft. Observations were made during periods when prevailing external meteorological conditions would exert minimum influence on the local thermal circulation. Over the land the depth of the layer of onshore flow is approximately 750 m and a maximum velocity of 5–7 m sec−1 is observed within 250 m of the surface directly over the lake shore. Above the lake breeze current a well defined return flow is apparent by midafternoon. The layer of return flow is about twice as deep as the lake breeze and velocities in the return flow axe proportionately lower. The local wind system extends through a depth exceeding 2500 m. Using climatological records it is demonstrated that flow can be in opposite directions on opposite sides of the lake, at least near the surface. Homogeneity of the lake breeze along the shoreline and the orderly progress of the lake breeze front to a distance exceeding 16 km inland are clearly apparent in the data. Evidence suggests that the structure and dimensions of the lake breeze wind system over the water are similar to those over the land. Turning of the local wind in response to the Coriolis force is also demonstrated by the observations. One cell of a symmetric lake breeze has been modelled numerically using the techniques developed by Estoque for the sea breeze with appropriate boundary condition modifications to account for the finite extent of the water surface. The temperature wave over the land was specified in accordance with observed temperatures on days when a lake breeze did occur. Results of the numerical forecast after 6 hr and after 9 hr of meteorological time are compared with the observed lake breeze at corresponding times.