- Last Updated on Friday, 02 August 2013 06:29
On Thursday 20 June 2013, there were two visitors at NARIT’s headquarters, Prof. Don McNeil from Macquarie University (Australia) and Chaloemchon Wannathong from Songkla Rajabhat University (Songkla, Thailand).
In this occasion, they gave two talks entitles. “Atmospheric clouds, ageing populations, cyber-bullying and cloud computing” by Prof. McNeil and “Analysis of Solar radiation data in Thailand: 1970-2010” by Mr. Chaloemchon Wannathong.
In first talk, Prof. McNeil had shown that the absorption of solar energy by the lower atmosphere is important and also had given a factor analysis of Australian data. He said that solar radiation is a huge untapped source of renewable energy. Unlike fossil fuel, it will last as long as we need it. Before it reaches the Earth’s surface, solar radiation is absorbed by the atmosphere, which has several layers. In addition, from his study of solar radiation energy, he simply divided the atmosphere into just two layers, lower and upper layers. The upper layer is the region where the amount of solar energy reaching its lower boundary which is a constant fraction of the extra-terrestrial (ET) solar radiation energy. ET is defined as the energy provided by the Sun before any atmospheric absorption. Since the total daily ET energy depends only on latitude and season, the lower atmospheric layer is thus the region where atmospheric clouds and other objects reduce daily solar radiation at a given location on the same day but in different years.
In the second talk, Mr. Chaloemchon illustrated his results of estimated percentage of solar radiation energy absorbed by clouds and other bodies in the lower atmosphere which varies with month of the year with patterns for different geographical locations in Thailand. However, while annual trends show variation, no overall increase or decrease over the 40-year period was evident. In all six meteorological stations in Thailand where solar energy was recorded, very few days had sufficiently clear skies to admit the 75% of extra-terrestrial radiation available after absorption by the upper atmosphere. This finding is difficult to explain unless the absorption percentage is around 70% rather than the 75% as assumed. As a result, data of two stations from October-December are incorrect. Further study is needed to understand how solar radiation is absorbed by the atmosphere.