How is the humidex calculated?
The Humidex formula is based on the work of J.M. Masterton and F.A. Richardson at the Atmospheric Environment Service (now MSC) of Environment Canada in 1979. It is a STANDARDS for Canada, but variations are used around the world. The dew point temperature should be given in kelvins (temperature in K = temperature in C + 273.1) for the formula to work. The magic number 5417.7530 is a rounded constant; it’s based on the molecular weight of water, latent heat of evaporation, and the universal gas constant. e = vapour pressure in hPa (mbar), given by: e = 6.11 * exp [5417.7530 * ( (1/273.16) – (1/dewpoint) ) ] h = (0.5555)*(e – 10.0); humidex = (air temperature) + h Note that the values associated with the discomfort of the humidex are generally for the outdoors. The Canadian Centre for Occupational Health and Safety recommends another index for indoors. For more information, visit: http://www.ccohs.ca/oshanswers/phys_agents/humidex.html Program designed to calculate the humidex Environme
