Australia's three main climate zones
CLIMATE ZONES FOR URBAN DESIGNSince the aim of climate-sensitive urban design is to provide the most comfortable thermal environment possible, the definition of climate zones for urban designers obviously has to be done by considering the climate variables which affect human comfort.
These variables are temperature, humidity or water vapour content of the air, heat radiated from the sun and from our surroundings and wind speed. Whether we feel too hot, too cold or (like the baby bear's porridge in the fairy tale) "just right", depends on the combined effect of these five quantities.
The heat radiated from our surroundings (terrestrial radiation) and the wind speed can vary considerably over small distances. For simplicity, only temperature and water vapour content of the air (humidity) have been used in the criteria for defining the climate zones.
A description of each climate zone and the definition used to set the boundaries on the map, follow.
Temperate ClimateThe temperate climate has mild to warm summers and cool winters. The need for winter home heating is greater than the need for summer cooling. It is a relatively comfortable climate, especially near the coast, where summers are cooler and winters warmer than further inland. In the mountains of the Great Dividing Range, winters are cold and summers are pleasantly mild.
Definition for zone boundary: mean January maximum temperature <= 30 degrees Celsius (Australian research suggests a temperature of 29.5 degrees Celsius as the upper limit for human thermal comfort) AND 3 pm January water vapour pressure <= 2.1 kPa (this is about the upper humidity limit for thermal comfort: the American Society of Heating, Refrigerating and Airconditioning Engineers use 1.87 kPa as the upper limit).
Hot Dry ClimateIn this climate, summers are hot to very hot and it seldom rains. Winter days may be cool or warm, and winter nights can be very cold. The air is dry, there is little cloud; sunshine is intense and glare can be a problem. There is a big temperature difference between day and night.
Definition for zone boundary: mean January maximum temperature > 30 degrees C AND 3 pm January water vapour pressure <= 2.1 kPa)
Warm Humid ClimateSummers in this climatic zone are warm, and very humid. In most parts of the zone, summer will be rainy. Winters are warm, dry and sunny. Coastal areas are subject to tropical cyclones (also known as hurricanes). The summer climate is stressful. It is the least comfortable Australian climate. The body's natural cooling system (the evaporation of perspiration) does not work well, because the air is already so full of water vapour that it cannot hold much more.
Definition for zone boundary: mean January water
vapour pressure >= 2.1 kPa (most places meeting this criterion
also have a wet bulb temperature
of about 24 degrees Celsius or more, which is the upper limit for any
effect from evaporative cooling).