Abstract

AOKI, Idalina Vieira et al. The climatogram of Lisbon following ETS standard. Corros. Prot. Mater. [online]. 2007, vol.26, n.2, pp.40-45. ISSN 0870-1164.

A climatogram is an envelope of climatic conditions defined by the characteristic severity of these conditions. A characteristic severity of a climatic parameter is determined by the extreme values of the parameter obtained from a statistical distribution of the measured air temperature (T) and the relative air humidity (RH) in a specified location for a long monitoring period. The climatogram of Lisbon, in Portugal, is presented. Lisbon is classified as a temperate climate region, with short winter season and long and warm summer period. Lisbon is located at 38º 43’ N of latitude and 9º 11’ W of longitude and an average atmospheric pressure of 1.0043 bar. The relative humidity is commonly very high which makes its climate very special and somewhat similar to those of the tropical regions. In this work 8519 paired T and RH values acquired for five years, in a time frequency of four hours intervals starting from 2:00a.m, summing up a total of six recordings per day that were used for constructing the climatogram. For every RH value there is an associated water partial pressure (p_A). Moreover, for each RH values an absolute humidity (AH) can be determined. So, with the known quantities T, RH and AH, the maximum and the minimum values with 1% and 10% probability of occurrence can be determined from the statistical distribution of the observed or calculated parameters using Minitab statistical software. Thus, the boundary values (extreme values of T and RH) of the climatogram square envelope can be obtained. In order to complete the envelope, a curve determined by the equation relating T and RH was drawn. There is an envelope for each percentile [1% (outer) or 10% (inner)] in the probability of occurrence plot. Comparisons between Lisbon climatogram and others obtained for regions of tropical climate are made, under the scope of the Tropicorr project, beneath the Cyted Programme in order to characterise the corrosivity of specific Ibero-American climates on materials used in electro-electronic devices to improve their reliability.

Keywords : Climatogram; Lisbon; Psychrometry; CYTED -Tropicorr Project.

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