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Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. [2] Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity depends on the temperature and pressure of the system of interest.
Water vapor can also be indirect evidence supporting the presence of extraterrestrial liquid water in the case of some planetary mass objects. Water vapor, which reacts to temperature changes, is referred to as a 'feedback', because it amplifies the effect of forces that initially cause the warming. Therefore, it is a greenhouse gas. [2]
The boiling point of water is the temperature at which the saturated vapor pressure equals the ambient pressure. Water supercooled below its normal freezing point has a higher vapor pressure than that of ice at the same temperature and is, thus, unstable. Calculations of the (saturation) vapor pressure of water are commonly used in meteorology.
A hygrometer is an instrument which measures the humidity of air or some other gas, that is, how much water vapor it contains. [1] Humidity measurement instruments usually rely on measurements of some other quantities such as temperature, pressure, mass, and mechanical or electrical changes in a substance as moisture is absorbed.
Pen says a great way to increase the humidity levels yourself is to mist your curtains with water. "The simplest yet effective tip is to mist your curtains with water using a spray bottle.
Because the amount of water vapor in the air is small, relative humidity, the ratio of the partial pressure due to the water vapor to the saturated partial vapor pressure, is much more useful. Vapor pressure above 100% relative humidity is called supersaturated and can occur if the air is rapidly cooled, for example, by rising suddenly in an ...
Water activity (a w) is the partial vapor pressure of water in a solution divided by the standard state partial vapor pressure of water. In the field of food science, the standard state is most often defined as pure water at the same temperature. Using this particular definition, pure distilled water has a water activity of exactly one.
Specific humidity is defined as the mass of water vapor as a proportion of the mass of the moist air sample (including both dry air and the water vapor); it is closely related to humidity ratio and always lower in value.