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Horizontal movement of air in the lower atmosphere due to wind.
Large body of air with approximately uniform temperature and water vapour throughout.
Instrument that determines altitude using atmospheric pressure.
Instrument used to measure wind speed and, in some cases, wind direction.
Difference from the average value.
For example, if the maximum temperature for June in Melbourne was 1 °C higher than the long-term average for this month, the anomaly would be +1 °C.
The international standard is to use the 30-year average from 1961 to 1990 as the long-term average. However, more recent periods (for example 1981 to 2010) will sometimes be used to calculate an anomaly that is more descriptive of the current climate. Anomalies calculated from periods of less than 30 years may not accurately describe all the variation that can be expected.
Also called high pressure systems, anticyclones are circulations of high air pressure that rotate anticlockwise in the southern hemisphere. They generally bring lighter winds and fine, settled conditions.
Apparent (‘feels like’) temperature measures how warm or cool you might feel, which can be different from the measured temperature. Our instruments measure ‘ambient temperature’ – how warm the air is in the shade and sheltered from the wind. However, apparent temperature also takes into account the effect of wind and humidity. It is based on a mathematical model of an adult walking outdoors in the shade.
Mapping system that sets mean sea level (measured from 1966 to 1968) as zero elevation. Australian mapping measures the height of features from this level.
Weatherproof enclosure that usually includes a thermometer, barometer and humidity probe. It may also have a rain gauge and anemometer attached, and communications equipment to transmit the data it collects in real time. An AWS takes automated measurements of weather elements, including some or all of these:
- air temperature
- humidity
- wind speed and direction
- atmospheric pressure
- precipitation
- soil temperature at various levels below ground
- sea level
- cloud base height
- horizontal visibility.
One of the 4 seasons in a year. In the southern hemisphere it’s March, April and May.