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Air density, like air pressure, decreases with increasing altitude. It also changes with variations in atmospheric pressure, temperature and humidity . At 101.325 kPa (abs) and 20 °C (68 °F), air has a density of approximately 1.204 kg/m 3 (0.0752 lb/cu ft), according to the International Standard Atmosphere (ISA).
Matter in the liquid state maintains a fixed volume (assuming no change in temperature or air pressure), but has a variable shape that adapts to fit its container. Its particles are still close together but move freely. Matter in the gaseous state has both variable volume and shape, adapting both to fit its container.
for dry air of 28.964917 g/mol. The specific gas constant of a gas or a mixture of gases ( R specific ) is given by the molar gas constant divided by the molar mass ( M ) of the gas or mixture: R s p e c i f i c = R M {\displaystyle R_{\rm {specific}}={\frac {R}{M}}}
Air pollution is the introduction of airborne chemicals, particulate matter or biological materials that cause harm or discomfort to organisms. [53] The population growth , industrialization and motorization of human societies have significantly increased the amount of airborne pollutants in the Earth's atmosphere, causing noticeable problems ...
The qualities of arctic air are developed over ice and snow-covered ground. Arctic air is deeply cold, colder than polar air masses. Arctic air can be shallow in the summer, and rapidly modify as it moves equatorward. [8] Polar air masses develop over higher latitudes over the land or ocean, are very stable, and generally shallower than arctic air.
If a gaseous emission sample is analyzed and found to contain water vapor and a pollutant concentration of say 40 ppmv, then 40 ppmv should be designated as the "wet basis" pollutant concentration. The following equation can be used to correct the measured "wet basis" concentration to a " dry basis " concentration: [ 3 ]
The study, which was published in February in the journal Nature Microbiology, found that influenza A viral particles can actually adapt their shape to remain infectious and stick around longer ...
The NASA Earth Global Reference Atmospheric Model (Earth-GRAM) was developed by the Marshall Space Flight Center to provide a design reference atmosphere that, unlike the standard atmospheres, allows for geographical variability, a wide range of altitudes (surface to orbital altitudes), and different months and times of day. It can also ...