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  Weather Parameters   Home > Weather Notes
 Information on Weather Notes...
   Air Temperature
   Heat Index
   Rainfall
   UV Index
   Comfort Index
   Surface Wind
   Sunshine
   Radiation
   Relative Humidity
   Pressure
   Broadband UV
 
Air Temperature Air Temperature
The instrument that measures temperature is a thermometer. Air temperature is measured in a well-ventilated screen that sheilds the thermometer from precipitation, direct exposure to sunlight, reflected radiation from surrounding structures that might affect the thermometer readings.
Heat Heat Index
Heat Index is an indicator used to determine the human perceived temperature (apparent temperature). Heat Index 1 is obtained using air temperature, humidity and wind. Heat index 2 is derived using all the weather parameters in Heat Index 1 with the addition of solar radiation. Therefore Heat Index 1 is the apparent temperature under the shade, while Heat Index 2 is the apparent temperature under the Sun. The Heat Index and Likelihood Heat Disorder information are as follow: Normal Heat Index 32>=Heat Index>29 ; Moderate Heat Index 40>=Heat Index>32 ; High Heat Index 52>=Heat Index>40 ; Danger Heat Index >52 ;
Rain Rainfall
The amount of liquid water precipitation from the atmosphere reaching the ground is measured using a rainfall recorder. Locally the rate of rainfall (rainfall intensity) definitions are Heavy Rainfall > 10mm/hr, Very Heavy Rainfall > 25 mm/hr, Extreme rainfall > 50 mm/hr.
UV UV Index
This is an indicator for UV radiation intensity on the surface.

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Comfort Comfort Index
This index is used to indicate the level of comfort. There are two Comfort Index which are derived from Heat Index. Comfort Index 1 indicates the comfort level indoors or in poorly ventilated shaded areas. The level of comfort out in a open shaded area with the influence of the ambient wind is shown by Comfort Index 2.

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Wind Surface Wind
Wind speed is the average of the bulk movement of air. Gust winds or maximum winds in this web-site are derived fom maximum of the 3-second averages. The average winds are derived from 1-minute wind averages.

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Sunshine Sunshine
The number of hours of sunshine in the day is measured with a glass crystal ball device. The clear glass ball focuses the sun rays that burn a track on a measuring time plate. Being located in the equator, Singapore receives a lot of sunshine.

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Radiation Radiation
Global Radiation is the incoming direct and diffuse infrared radiation from the sun. It is measured in Watt per meter square. On most cloudless day, the solar irradiation in Singapore reaches almost the peak incoming solar irradiation from the sun. However sometimes the solar irradiation can exceed the solar constant because of reflection from the nearby large cumulus clouds.

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Humidity Relative Humidity
The air at any given time can only contain a limited quantity of water vapour. When the water vapour content in the air reaches this limit, the air is saturated. Usually the amount of water vapour present in air is less than the saturation amount. Relative Humidity indicates the percentage of the amount of water vapour present in the air with respect to the saturated amount.

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Pressure Pressure
The weight of the column of air

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BroadbandUV Broadband UV
The measurements of the total UV radiation. UVA UVB and UVC.

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Last updated on 10/01/2010
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