Wind Chill - Formulae and Tables - Australian Apparent Temperature

Australian Apparent Temperature

The Australian Bureau of Meteorology uses a different formula for cooler temperatures.

The formula is:

Where:

Dry bulb temperature (°C)
Water vapour pressure (hPa)
Wind speed (m/s) at an elevation of 10 meters

The vapour pressure can be calculated from the temperature and relative humidity using the equation:

Where:

Dry bulb temperature (°C)
Relative Humidity
represents the exponential function

The Australian formula includes the important factor of humidity and is somewhat more involved than the simpler North American model. However humidity can be a significant factor. The North American formula is designed mainly on the basis that it is expected to be applied at low temperatures, when humidity levels are also low, and also for much colder temperatures (as low as -50F). As these are qualitative models this is not necessarily a major failing.

A more exhaustive model (which factors in Wind Speed) was developed for the US Navy stationed in Parris Island in South Carolina. It was developed with a consideration for Heat Stroke due to the high humidity off the Island during summer months. It utilized three specialized thermometers. This research is what the Australian Apparent Temperature formula was derived from.

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