Arden Buck model (1981 & 1996 improvements) with the enhancement factor model: P_sat = fw ( a × exp((b - T/c) × T/(T + d)) ). Accurate saturation vapor pressure calculations from -20°C to 50°C.

The humidity ratio is a fundamental measure of humidity and it is defined as the ratio of the amount of water vapor to dry air in a given air sample of humid air. In other words, a humidity ratio of 10g/kg indicates that the humid air has 10 grams of water vapor for every kilogram of dry air. The humidity ratio is calcculated as W = (R_da / R_v) × P_v / (P - P_v) ; where 'da' refers to dry air, and 'v' stands for water vapor.

The specific humidity indicates the amount of water vapor present in a kilogram of humid air mixture, while the humidity ratio (W) indicates the ratio between the amount of water vapor to dry air present in a kilogram of humid air. By definition, the specific humidity (q) is calculated from the humidity ratio as: q = W/(1 + W). Be careful because these two metrics are often confused or used interchangeably!

h = cp_da × T + W × (cp_v × T + h_we) ; where h_we is the latent heat of vaporization of water at 0°C.

Magnus Tetens model. Estimated uncertainty of 0.35 °C for -40 °C <= T <= 50°C.

The kilograms of water (m_w) dispersed in N kilograms of humid air can be calculated as m_w = (N × W) / (W + 1) , where the humidity ratio (W) can be calculated from the relative humidity (RH) and saturated water vapor pressure P_s as W = (R_da / R_v) × (RH × P_s) / (P - RH × P_s)

You can ask the Ai assistant, it should be able to reply to most thermodynamics related questions you might have. Keep in mind that the AI-bot does not have the full access to the list of models used in the source code of the website.