SOLAR RADIATION AND ITS INFLUENCE ON OTHER CLIMATIC PARAMETERS IN VALLETTA, MALTA

摘要

An investigation was carried out to determine the relationship between solar radiation and various climatic parameters for the local environment of the city of Valletta. A Campbell weather station was installed on the roof of a church in Valletta to record weather parameters automatically. These parameters were air relative humidity, the air temperature, solar radiation, wind speed and wind direction, rainfall and surface temperature on the dome apex, on the south-east and north-west aspects. The monitoring lasted a year, from 1˜st June 1999 to 22˜nd May 2000. The recorded data was plotted against time for further analysis. The plots included the distribution of monthly climatic parameters over a year as well as the distribution of daily climatic parameters over each month. The mean monthly radiation varied between a peak value of 6.9kWh/ m² in June and a minimum value of 1.9kWh/ m² in November. For an increase in radiation values, a corresponding increase in air temperature values started registering only after a phase lag of about two months, by which time radiation values had started to decrease. The effect of the wind and its direction and cloud cover additionally influenced temperature levels. During August, since wind speeds were low, mostly below 2m/s, radiation values greatly affected temperature values that reached their highest daily value some hours after the peak radiation level. In contrast, the surface temperatures were quicker to register an increase with a rise in radiation levels, the south-east surface temperature being much higher than that on the north-west.