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Direct and diffuse solar radiation information added to
Observatory's website (1 April 2010)

The Hong Kong Observatory today (1 April) starts adding real-time measurements of direct and diffuse solar radiation in Hong Kong, in addition to global solar radiation, to its website.

Direct solar radiation is the part of the sunlight that reaches the surface of the earth straight through the atmosphere. The remaining part of the sunlight, known as diffuse solar radiation, takes a more indirect route as it becomes scattered or reflected by air molecules, water vapour and dust. Global solar radiation is all the sunlight that reaches the earth's surface and is merely the sum of the direct and diffuse solar radiation.

Knowing the amount of solar radiation is very important as the sun provides the most abundant renewable energy source. It is generally agreed within the scientific community that if we could harness all that solar energy reaching the earth's surface over one hour we could satisfy the global energy need for one year. Developing technology to efficiently harness the energy and convert it into usable electrical energy is rapidly becoming a major interest in the global effort to create a cleaner future, free from reliance on fossil fuels. Information on direct and diffuse solar radiation can help in the design and construction of energy efficient structures that do not require extensive air conditioning by appliances such as heaters or coolers.

Since 1958, the Hong Kong Observatory has been measuring global solar radiation. Currently, the Observatory measures direct and diffuse solar radiation at King's Park Meteorological Station and Kau Sai Chau Solar Station in Sai Kung. Measurements of diffuse solar radiation are made by a pyranometer that is shaded from the sun, while direct solar radiation is measured by a pyrheliometer mounted on a sun tracker that ensures that it points directly at the sun all the time. Information on the direct and diffuse solar radiation in addition to the existing global solar radiation information from King's Park and Kau Sai Chau is now available on the Observatory's "Regional Weather" webpage in real-time at: 
www.weather.gov.hk/wxinfo/ts/display_element_solar_e.htm

 
Picture shows the direct and diffuse solar radiation instruments (left) in Kau Sai Chau Solar Station mounted on a sun tracker and the global solar radiation sensor (right).
Picture shows the direct and diffuse solar radiation instruments (left)
in Kau Sai Chau Solar Station mounted on a sun tracker
and the global solar radiation sensor (right).

 
Time series of the direct and diffuse solar radiation measured at the Kau Sai Chau Solar Station.
Time series of the direct and diffuse solar radiation measured
 at the Kau Sai Chau Solar Station.

 

 

Last revision date: <21 Dec 2012>