Compute saturation vapor pressure with the Magnus or Tetens formula.
由气温，按 Magnus 公式 e_s = 6.1094·exp(17.625T/(T+243.04)) 计算饱和水汽压。
| Item | Formula | Source / Standard |
|---|---|---|
| Magnus saturation vapour pressure | es = 6.112 exp(17.62 T / (243.12 + T)) | WMO Magnus-Tetens formula |
| Over water saturation pressure | ew = 6.112 exp(17.62 T / (243.12 + T)) | WMO Guide to Instruments (WMO-No. 8) |
| Over ice saturation pressure | ei = 6.112 exp(22.46 T / (272.62 + T)) | WMO Guide to Instruments (WMO-No. 8) |
Constants and standards used on this page with their authoritative sources, for verification and citation.
| Quantity | Value | Unit | Source |
|---|---|---|---|
| Magnus / Tetens form (this page) | 6.1094·exp(17.625T/(T+243.04)) | hPa | Tetens (1930); coefficients after Alduchov & Eskridge (1996) |
| Coefficient at 0 °C | 6.1094 | hPa | 0 °C value of the Tetens/Bolton parameterisation |
| Bolton parameterisation (reference) | 6.112·exp(17.67T/(T+243.5)) | hPa | Bolton D. (1980), Mon. Wea. Rev. 108:1046-1053 |
| WMO reference formulations | Goff-Gratch (1946), Buck (1996) | — | WMO CIMO Guide, WMO-No.8 Vol. I Ch. 4 |
| hPa to mmHg conversion | 0.750062 | mmHg/hPa | 1 mmHg = 133.322 Pa (BIPM / ISO 80000), 1 hPa = 100 Pa |
| hPa to Pa conversion | 100 | Pa/hPa | SI prefix definition (h = 10²) |
Note: the Magnus form is an engineering approximation, typically within 0.5% of measurements for 0-50 °C; use IAPWS-95 above 50 °C or for high accuracy.