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Climate Change in Hong Kong - Cloud amount, solar radiation and evaporation

Climate Change in Hong Kong

Cloud amount, solar radiation and evaporation


In Hong Kong, cloud amount is reported in oktas hourly by trained observers at the Hong Kong Observatory Headquarters. The annual mean cloud amount has a generally increasing trend. One potential cause for the increase in cloud amount over Hong Kong could be the likely increase in the concentration of condensation nuclei in the air that favoured the formation of clouds, which is known to be associated with urbanization and human activities in the region.

annual mean cloud amount recorded at the hong kong observatory headquarters from 1961 to 2019

Annual mean cloud amount recorded at the Hong Kong Observatory Headquarters (1961-2019)

 

» Cloud amount data

 

Both the increase in the concentration of suspended particulates and the increase in cloud amount will reduce the amount of solar radiation reaching the surface. At King's Park (a meteorological station located 900m north of the Hong Kong Observatory Headquarters in urban Kowloon), the amount of solar radiation reaching the surface is recorded continuously by thermo-electric pyranometers.

Annual mean daily total global solar radiation at King's Park (1968-2019)

Annual mean daily total global solar radiation at King's Park (1968-2019)

 

» Solar radiation data

 

Evaporation measurements are made daily at King's Park using evaporation pans with evaporation surface 0.18 m above ground. In general, the amount of evaporation depends on the amount of solar radiation received, the relative humidity as well as the wind speed.

Annual total evaporation at King's Park (1961-2019)

Annual total evaporation at King's Park (1961-2019)

 

» Evaporation data