More UV InformationBureau of Meteorology - Forecast UV Index for Melbourne
The Cancer Council Australia - SunSmart
CS Weather UV Page
Sources for Graph definitionsDavis Instruments glossary
The Weather Channel
Wikipedia (Density of Air)
Lookout Point Weather (THSW)
Weekly Climate Information
|The pressure exerted by the atmosphere at a given point. Its measurement can be expressed in several ways. One is in millibars. Another is in inches or millimeters of mercury (Hg), or hectopascals (hPA). Hectopascal, a measurement of barometric pressure. One hPA equals 100 pascals or one millibar. One pascal is equal to a force of one Newton over an area of one square meter
||Temperature. The measure of molecular motion or the degree of heat of a substance. It is measured on an arbitrary scale from absolute zero, where the molecules theoretically stop moving. It is also the degree of hotness or coldness. In surface observations, it refers primarily to the free air or ambient temperature close to the surface of the earth
||Humidity. The ratio of the actual amount of water vapour in the air to the maximum amount of water vapour the air could hold at that temperature. More precisely called relative humidity.
|Precipitation in the form of liquid water droplets greater than 0.5 mm. If widely scattered, the drop size may be smaller.
||Dew Point. A measure of humidity stated in terms of the temperature at which the air would be saturated and dew would begin to form if the amount of water vapor in the air were held constant.
|Wind Chill. The combination of temperature and wind speed. When the wind is blowing, it carries away the air that has been warmed by your body. It feels as if the temperature is lower than it really is.
||The combination of air temperature and humidity that gives a description of how the temperature feels. This is not the actual air temperature.
||Highest Daily Windspeed
|Direction of High Daily Windspeed
|Solar Radiation. The electromagnetic radiation emitted by the sun. Solar radiation sensors actually measure incident solar radiation or solar irradiance, which is the amount of radiant power per unit area that flows across or onto a surface.W/m². Watts per square meter, a measurement of solar radiation. One watt is equal to 0.143 Kg-calories/minute or 1 volt-ampere.
||Highest Solar Radiation reading for each day shown
||Solar Energy. The energy transmitted from the sun in form of electromagnetic radiation, measured in Langleys (Ly). One Langley is equal to one gram-calorie per square centimetre. A gram-calorie is the amount of heat required to raise the temperature of one gram of water one degree Celsius.
|Energy from the sun reaches the earth as visible, infrared, and ultraviolet (UV) rays. Exposure to UV rays can cause numerous health problems, such as sunburn, skin cancer, skin aging, and cataracts, and can suppress the immune system. CAUTION: The station's UV readings do not take into account UV reflected off snow, sand, or water, which can significantly increase your exposure. Nor do your UV readings take into account the dangers of prolonged UV exposure. The readings do not suggest that any amount of exposure is safe or healthful. Do not use the Vantage Pro to determine the amount of UV radiation to which you expose yourself. Scientific evidence suggests that UV exposure should be avoided and that even low UV doses can be harmful.
||Highest UV reading for each day shown
||MED. Minimal Erythemal Dose, a measurement of UV dose. Erythema is the reddening of the skin due to capillary congestion. Sunburn is among the most common forms of erythema.
|Evapotranspiration. The amount of water transferred from the earth to the atmosphere due to the combined effects of evaporation and transpiration. Transpiration is the process by which plants release water vapour into the air.
||A cooling degree day is given for each degree that the daily mean temperature departs above the baseline of 23.9° C. It is used to estimate the energy requirements and is an indication of fuel consumption for air conditioning or refrigeration.
||One heating degree day is given for each degree that the daily mean temperature is below 18.3°C. It is used as an indication of fuel consumption.
|The THSW Index uses humidity and temperature like the Heat Index, but also includes the heating effects of sunshine and the cooling effects of wind (like Wind chill) to calculate an apparent temperature of what it “feels” like out in the sun
||For any given combination of temperature and relative humidity conditions, there is an equilibrium moisture
content (EMC) for a piece of wood. The stations Inside Temperature and Inside Humidity are used to calculate EMC.
|The density of air is the mass per unit volume of Earth's atmosphere. Air density decreases with increasing altitude and temperature. At sea level and at 20 °C, dry air has a density of approximately 1.2 kg.
||Wind Run. Calculated by multiplying the wind speed by the measurement period and summing over time. If the wind speed was a constant 10 kilometres per hour for three hours, the wind run would equal 30 kilometres.