Utility functions for calculating the Apparent Temperature (AT).

Calculate apparent temperature (AT) from air temperature, relative humidity,

and wind speed.

The Australian Apparent Temperature (AT) is a type of heat index that was used by the Australian Bureau of Meteorology (ABM). It is based on a mathematical model published by Robert G. Steadman in 1994 [1]. Two forms of the model are available, one including radiation and one without. This algorithm uses the non-radiation version. [2]

Note

[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/

Parameters
• ta – Air temperature [C]

• rh – Relative humidity [%]

• ws – Wind speed (km /h)

Returns

at – Apparent Temperature[C]

Get the category of apparent suggestion associated with a given apparent temperature (AT).

Categories to indicate apparent suggestion:

• 4 = (>40 C) Minimal clothing; sun protection required.

• 3 = (35-40 C) Minimal clothing; sun protection as needed.

• 2 = (30-35 C) Short sleeve, shirt and shorts.

• 1 = (25-30 C) Light undershirt.

• 0 = (20-25 C) Cotton-type slacks (pants).

• -1 = (15-20 C) Normal office wear.

• -2 = (10-15 C) Thin or sleeveless sweater.

• -3 = (5-10 C) Sweater. Thicker underwear.

• -4 = (0-5 C) Coat and sweater.

• -5 = (-5-0 C) Overcoat. Wind protection as needed.

• -6 = (<-5 C) Overcoat. Head insulation. Heavier footwear.

Parameters

at – Apparent temperature [C]

Returns

category – An integer indicating the level of warning associated with the heat index. Values are one of the following:

• 4 = Minimal clothing.

• 3 = Minimal clothing.

• 2 = Short sleeve, shirt and shorts.

• 1 = Light undershirt.

• 0 = Cotton-type slacks (pants).

• -1 = Normal office wear.

• -2 = Thin or sleeveless sweater.

• -3 = Sweater. Thicker underwear.

• -4 = Coat and sweater.

• -5 = Overcoat.

• -6 = Overcoat.