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Understanding the Weather
How is the UV index measured?
The UV index is measured using two methods.
The first method measures the amount of energy contained in the UV radiation reaching the surface. This method expresses energy in milliwatts per square metre. The UV index you see on your TV news bulletins is based on this method.
The second method is based on the response of human skin to UV radiation. This was devised to standardize UV radiation reporting around the world. It is often used as a prediction. The index is determined for the time at which UV intensity is at its peak. This is usually around noon. It takes into account cloud cover.
UV Index values of less than 3 are termed “moderate” and will result in sunburn after one hour exposed to the sun. Index values between 3 and 6 are termed “high” and will lead to sunburn after approximately 30 minutes in the sun. Values between 6 and 10 are termed “very high” and will lead to sunburn after approximately 10 minutes in the sun. Values greater than 10 are termed “extreme” and will lead to sunburn in less than 5 minutes exposed to the sun.
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- Do you have an explanation of the terminology you use in weather forecasts?
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A very wet weekend for southeast Qld, northeast NSW
11:48 AEST A prolonged rainfall event is set to bring large totals to parts of NSW and Qld from Saturday, with possible heavy falls and flooding. A low-pressure system in the Coral Sea, a deepening coastal trough and persistent easterlies will bring moisture-laden air into southeast Qld and northeast NSW will bring days of rainfall to the region. While there is not a drop of rain on the radar over southeast Qld and Northeast NSW on Friday morning, the mass of cloud associated with a low in the Coral Sea will enhance rainfall over the weekend.
- 10:07 AEST Southerly surges across the southeast
- 13:20 AEST Generation gone with the wind
- 11:29 AEST Devilishly dry in Tasmania
- 16:41 AEST Dubai deluge: a year's rainfall in a day
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