absolute humidity


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humidity

 [hu-mid´ĭ-te]
the degree of moisture in the air.
absolute humidity the actual amount of vapor in the atmosphere, expressed in milligrams per liter.
relative humidity the percentage of moisture in the air as compared to the amount necessary to cause saturation, which is taken as 100.
humidity therapy the therapeutic use of water to prevent or correct a moisture deficit in the respiratory tract. Under normal conditions the respiratory tract is kept moist by humidifying mechanisms that allow for evaporation of water from the respiratory mucosa. If these mechanisms fail to work, are bypassed (such as with an endotracheal tube), or are inadequate to overcome the drying and irritating effects of therapeutic gases and mucosal crusting, some form of humidification must be provided.

The principal reasons for employing humidity therapy are: (1) to prevent drying and irritation of the respiratory mucosa, (2) to facilitate ventilation and diffusion of oxygen and other therapeutic gases being administered, and (3) to aid in the removal of thick and viscous secretions that obstruct the air passages. Another important use of water aerosol therapy is to aid in obtaining an induced sputum specimen.

Humidity therapy may be delivered in a variety of ways. Humidifiers and vaporizers increase the water content of an environment and are limited to the treatment of upper respiratory disorders because they produce particles that are too large to penetrate deeply into the lungs. Nebulizers generate clouds or mists of particles that are extremely small and thus capable of penetrating more deeply into the bronchioles and small structures of the lower respiratory tract. Examples of these include jet instruments and ultrasonic nebulizers.

ab·so·lute hu·mid·i·ty

the mass of water vapor actually present per unit volume of gas or air.

absolute humidity

the actual mass or content of water in a measured volume of air. It is usually expressed in grams per cubic meter or pounds per cubic foot or cubic yard.

ab·so·lute hu·mid·i·ty

(ab'sŏ-lūt' hyū-mid'i-tē)
The mass of water vapor actually present per unit volume of gas or air.
References in periodicals archive ?
The analysis indicates not only that absolute humidity profiles and land-cover types can be used to distinguish between areas with high and low risk of epidemics but also that population density and dust may also be implicated.
Consequently, outbreaks of influenza typically occur in winter when low absolute humidity conditions strongly favour influenza survival and transmission," he added.
For both experiments, the average of the absolute humidity was [bar.
Figure 4c shows the behavior of the duct air absolute humidity obtained through simulation.
First, the "typicalness" of the TMY3 derived by Wilcox and Marion (2008) was evaluated for seven variables - total sky cover, dry-bulb temperature, dew-point temperature, relative humidity, absolute humidity, pressure, and wind speed.
9 absolute humidity) have a similar frost mass and frosting period, a decrease of only 10% in relative humidity, that is, a decrease of the absolute humidity from 3.
The difference in absolute humidity ([omega]) between the incoming outdoor air and supply air leaving the unit represents the amount of condensation that occurs.
Since relative humidity depends on both pressure and temperature, the relative humidity varies during the pressure and temperature sensitivity tests; however, the absolute humidity remained constant.
For over 90% of the hours in a year, the indoor conditions can be met by mixing outside and return air (the psychrometric process of this mode is shown by the arrows in Figure 5, which is to first order along lines of constant absolute humidity, since there is negligible latent load in the HPC).
inf air] is the absolute humidity ratio of air infiltrating the freezer (lbw/lba), and [[omega].