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.

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 ?
[DELTA]W = absolute humidity difference between the cavity and the surroundings
[[omega].sub.f] = absolute humidity ratio of the freezer air, lbw/lba
With reference to the ability of the DDC system to control to an absolute humidity or dew-point setpoint, the need for a thorough commissioning program at the inception of the project, coupled with a program of continuous retrocommissioning throughout the life of the facility, cannot be stressed enough.
Three of the four daily loads into the ice are lowest in winter and highest in summer, due to the corresponding changes of the outdoor dry-bulb temperature and absolute humidity. The influence of the climate on ground gains is very small, while daily loads from resurfacing and dissipation are independent of climatic conditions.
This method will lower the RH% after cold air is re-heated, and it also will reduce absolute humidity. However, efficiency falls significantly as air temperatures fall below 50[degrees]F (10[degrees]C).
The seasonal increase of influenza long has baffled scientists, but a study published in PLoS Biology has found that seasonal changes of absolute humidity are the apparent underlying cause of these wintertime peaks.
These airbags could explode if deployed in a frontal crash, due to propellant degradation occurring following long-term exposure to absolute humidity and temperature cycling.
The relative air humidity in the experiment room was relatively higher than that in the comparison room, which can be explained by the increase in absolute humidity due to the combustion activity (Figures 12 and 13).
The test cases at 35[degrees]C, 50% RH and 30[degrees]C, 66% RH have around the same absolute humidity of 20 g/[m.sup.3].
This gradient is determined by the surface temperature of the water, the absolute humidity in the atmosphere (e.g., vapor pressure), and the amount of turbulent mixing of air, resulting in high evaporation rates when the water is warm and the air is cold, dry, windy, and unstable.
We used relative humidity rather than absolute humidity for 2 reasons.