Australian Apparent Temperature (AT)

The Australian Apparent Temperature (AT)  calculator computes the apparent temperature (AT) based on the dry ambient temperature (Ta), the relative humidity (rh) and the wind speed at ten meters (ws).

INSTRUCTIONS: Choose units and enter the following:

• (Ta)  Dry Ambient Temperature
• (rh)  Percent Relative Humidity.
• (ws)  Wind Speed at 10 meters.

Apparent Temperature (AT): The calculator returns the apparent temperature in degrees Celsius.  However, this can be automatically converted to compatible units via the pull-down menu.

The Math / Science

The Australian Apparent Temperature (AT) is a type of heat index that was used by the Australian Bureau of Meteorology. It is based on a mathematical model published by Robert G. Steadman in 1994.¹ It can account for the impacts of temperature, humidity, wind-speed and radiation on the heat balance of the human body. Two forms of the model are available, one including radiation and one without. This algorithm uses the non-radiation version.²

This version of the Steadman Apparent Temperature does not account for solar radiance. As such, AT is calculated as:

AT = T_a + 0.33•ρ − 0.70•ws − 4.00

and

ρ = rh • 6.105 • e^{(17.27*T_a/(237.7+T_a))}

where:

• AT = Apparent Temperature in °C;
• T_a = Dry bulb Temperature in °C;
• ρ = water vapor pressure (hPa);
• ws = wind speed (m/s) at 10 meter above the ground;
• rh = Relative Humidity (%).

Weather (Meteorology) Calculators

• Heat Index: Approximates the heat index based on the temperature and relative humidity
• Canadian Humidity Index (HUMIDEX): Computes the Canadian Humidity Index (HUMIDEX) based on the dry-bulb ambient temperature and the dew-point temperature.
• Australian Apparent Temperature (AT): Computes the apparent temperature based on the dry ambient temperature, the relative humidity and the wind speed at ten meters.
• Relative Humidity: Computes the relative humidity based on the actual density of vapor and the saturated density.
• Dew Point from Relative Humidity: Computes the dew point based on the relative humidity and ambient temperature.
• Summer Simmer Index: Computes the Summer Simmer Index based on the air temperature and relative humidity.
• Wind Chill Index (North America): Computes the wind chill index based on the air temperature and the velocity of the wind.
• Wet-Bulb Globe Temperature (WBGT): Computes the wet-bulb globe temperature index based on dry-bulb (air) temperature, globe thermometer temperature and the wet-bulb temperature.
• Humature Index: Estimates the humidity index based on the temperature and dew point.
• Antoine Equation: Computes the apparent vapor pressure of pure substances based on temperature and coefficients for the substance.
• Barometric Formula (Tropospheric) calculator computes the normal barometric pressure based on the altitude (h) using the Exponential Atmosphere formula.
• Planetary Temperature: Estimates a planet's temperature based on the luminosity of its star, distance to the star, average albedo and infrared optical depth of atmosphere.
• Snow Water Equivalent (SWE): Computes the volume of liquid water contained in rain or snow pack defined by area, depth and snow type or rain.

Australia Calculators

• US Dollars per Gallon from Australian Dollars per Liter
• US Dollars per Australian Dollars ($0.628 USD)
• Australian Dollars per US Dollar ($1.592 AUD)
• Australian Apparent Temperature (AT)

References

1.Steadman, R. G. (1994). Norms of apparent temperature in Australia. Aust. Met. Mag, 43, 1-16.

2. Thermal Comfort observations. (n.d.). Retrieved May 20, 2016, from http://www.bom.gov.au/info/thermal_stress/