what is humidity?

Answer 1

water vapor in the air

Answer 2

There are several types of humidity. By far the most common one is "relative humidity", which is what gets mentioned during weather reports/forecasts.

Relative humidity is defined as the ratio of the vapor pressure due to water vapor divided by the saturation vapor pressure times 100. So if the vapor pressure due to water is the same as the saturation vapor pressure, the relative humidity is 100%.

Vapor pressures are directly related to the temperature of the air. So as the temperature rises, the relative humidity drops (as long as the amount of water vapor remains constant). This is why the relative humidity is usually highest early in the morning, when the temperature is generally at its lowest.

That last point is important when thinking about heating your home. If you bring in outside air at 32 degrees F and heat it up to 70F, you are drastically lowering the relative humidity. This explains why houses without humidifiers are extraordinarily dry in the winter.

It is nearly impossible to have natural air at 0% relative humidity. Even the driest air in the Western United States only gets down to 5-10% relative humidity.

Answer 3

Dampness, especially of the air.

Amount of water vapour in the air. One of the most variable characteristics of the atmosphere, humidity is an important factor in climate and weather: it regulates air temperature by absorbing thermal radiation both from the Sun and the Earth; it is directly proportional to the latent energy available for the generation of storms; and it is the ultimate source of all forms of condensation and precipitation. Humidity varies because the water-holding capacity of air is determined by temperature. When a volume of air at a given temperature holds the maximum amount of water vapour possible, the air is said to be saturated. Relative humidity is the water-vapour content of the air relative to its content at saturation. Saturated air has a relative humidity of 100%; near the Earth the relative humidity rarely falls below 30%.


Atmospheric water-vapor content, expressed in any of several measures, especially relative humidity, absolute humidity, humidity mixing ratio, and specific humidity.

Relative humidity is the ratio, in percent, of the moisture actually in the air to the moisture it would hold if it were saturated at the same temperature and pressure. It is a useful index of dryness or dampness for determining evaporation, or absorption of moisture. See also Psychrometrics.

Absolute humidity is the weight of water vapor in a unit volume of air expressed, for example, as grams per cubic meter or grains per cubic foot.

Humidity mixing ratio is the weight of water vapor mixed with unit mass of dry air, usually expressed as grams per kilogram. Specific humidity is the weight per unit mass of moist air and has nearly the same values as mixing ratio.

Answer 4

humidity is the amount of water vapor in the air

Answer 5

The water vapor in the air.

Answer 6

amount of moisture in the air