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Explanatory Notes



Air temperature and relative humidity reporting

Air temperatures and relative humidities shown on this webpage are instantaneous readings recorded at the automatic weather station, while air temperatures and relative humidities in the hourly bulletin "Current Weather" are manually taken by weather observers during a ten-minute period before the end of the hour. The temperatures and relative humidities on the hour shown on this webpage and the temperatures and relative humidities reported in the hourly bulletin "Current Weather" may be taken at different instants and hence may not be the same.


Wind barbs

circle :  calm
VRB :  variable
symbol :  Easterly wind of 18 kilometres per hour
symbol :  Easterly wind of 90 kilometres per hour

Symbol   Descriptive Term Beaufort Force
symbol :  Strong force wind Force 6
symbol :  Gale force wind Force 8
symbol :  Storm force wind Force 10
symbol :  Hurricane force wind Force 12


Visibility reporting

Visibility is reported according to World Meteorological Organization guidelines as summarized in the following table:

Measured Visibility Rounded down to the nearest
100 metres - 4999 metres 100 metres
5 kilometres - 30 kilometres 1 kilometre
31 kilometres - 50 kilometres 5 kilometres

For example:
(i) measured visibility of 1680 metres is reported as 1600 metres;
(ii) measured visibility of 7900 metres is reported as 7 kilometres;
(iii) measured visibility of 37 kilometres is reported as 35 kilometres.

Last revision date: <19 Dec 2012>