- noun a ratio between the amount of water vapour in air and the amount that would be present if the air was saturated, shown as a percentage
- The ratio of the quantity of water vapor actually present to the amount present in a saturated atmosphere at a given temperature, expressed as a percentage.
- The amount of water vapour in air as a percentage of the total amount the air could hold at the same temperature and pressure. If liquid water is present as fog or steam then the relative humidity will be 100 per cent. At 100 per cent relative humidity no evaporation of sweat or water can take place.
- noun the mass of moisture in a given volume of air expressed as a percentage of the moisture required to saturate the same volume of air at a particular temperature