Pressure in the Atmosphere

This is defined as the percentage ratio of the water vapour pressure in the atmosphere compared to that which would saturate the atmosphere at the same temperature. Alternatively, the difference in temperature between the ambient atmosphere and that to which it would have to be cooled before moisture condensed from it, is also used as a measure of moisture content. This difference in temperature is called the dew point depression. The actual temperature at which condensation takes place is known as the dew point. The relative humidity is then expressed as ... 

Between oxygen pressures of 2-8 x 10" and 8 x 10 atm the outermost oxide layer will consist of the MO phase. Its exact surface composition can be predicted by using the common tangent in the same manner as described for MO. From Fig. 7.84 it is clear that, as the oxygen pressure in the atmosphere is reduced the composition of the surface oxide layer will vary in a predictable manner from Xq = 0-55 to Xq = 0-475. 

A deliquescent material takes up moisture freely in an atmosphere with a relative humidity above a specific, well-defined critical point. That point for a given substance is defined as the critical relative humidity (RH0). Relative humidity (RH) is defined as the ratio of water vapor pressure in the atmosphere divided by water vapor pressure over pure water times 100% [RH = (PJP0) X 100%]. Once moisture is taken up by the material, a concentrated aqueous solution of the deliquescent solute is formed. The mathematical models used to describe the rate of moisture uptake involve both heat and mass transport. 

Dry air rising in the atmosphere has to expand as the pressure in the atmosphere decreases. This pV work decreases the temperature in a regular way, known as the adiabatic lapse rate, Td, which for the Earth is of order 9.8 Kkm-1. As the temperature decreases, condensable vapours begin to form and the work required for the expansion is used up in the latent heat of condensation of the vapour. In this case, the lapse rate for a condensable vapour, the saturated adiabatic lapse rate, is different. At a specific altitude the environmental lapse rate for a given parcel of air with a given humidity reaches a temperature that is the same as the saturated adiabatic lapse rate, when water condenses and clouds form Clouds in turn affect the albedo and the effective temperature of the planet. Convection of hot, wet (containing condensable vapour) air produces weather and precipitation. This initiates the water cycle in the atmosphere. Similar calculations may be performed for all gases, and cloud layers may be predicted in all atmospheres. 

In turn, the concentration of C02 in the atmosphere depends on the mass of the biosphere and its rate of decay after death, and on the carbonic-anhydrase concentrations in the sea surface. In future predictions of the rate of increase of C02 partial pressure in the atmosphere due to burning fossil fuels, it will be important to include the interaction of the atmospheric C02 with the bio-organic reservoir and the catalyzation of its absorption into the sea by means of the action of carbonic-anhydrase dissolved in sea water, considerations which have not been taken into account in past computations. 

FIGURE 4.2. Partial pressure of H2S measured in ppm on a volumetric basis in the atmosphere in equilibrium with a water phase of sulfide [cf. Equations (4.8) and (4.12)]. The curves show the equilibrium partial pressure in the atmosphere per unit concentration in the water phase. 

For gases and vapors, the amount absorbed is highly dependent on the partial pressure of the gas and the solubility of the gas in blood. Let s take the simple case of a gas that is not metabolized and is excreted by exhalation (e.g., an anesthetic gas or a Halon-type fire-extinguishing agent). At any given concentration (or partial pressure) in the atmosphere, the concentration in the blood will reach a steady state in the blood. Accordingly, prolonged exposure does not lead to continual buildup. 

Bunsen solubility coefficient (a ) The term that relates the concentration of a gas in seawater to its partial pressure in the atmosphere. It is dependent on temperature and salinity. 

Table 3.7 Henry s law constants for important gases in submerged soils at 25 °C and typical partial pressures in the atmosphere ...

Eriksson (1963) found that a 1 % increase in alkalinity causes a 2.26% decrease in C02 partial pressure in the atmosphere and a 98% reduction of total C02 supply in the hydrosphere. Under conditions where there is no external input of Ca into the hydrosphere, a 1% increase in alkalinity causes an increase in the rate of CaC03 deposition (i.e., total alkalinity decreases by 0.92%). Thus, a 1% increase in water alkalinity is equivalent to a 0.5 increase in pH. 

The connection between the equilibrium condition of C02 exchange and pH on the atmosphere-ocean border is such that when the C02 pressure in the atmosphere... 

Pa PACE PAGES PAHO PALE PAR PARCS PBL PCM PDV PhA PIK PIRA PIRATA POC POLDER Partial pressure in the atmosphere Permafrost And Climate in Europe Pilot Analysis of Global EcoSystems Pan American Health Organization Paleoclimates of Arctic Lakes and Estuaries Photosynthetic Active Radiation Paleoenvironmental ARCtic Science Planetary Boundary Layer Parallel Climate Model Pacific Decadal Variability Phytogenic Aerosol Potsdam-Institut fur Klimafolgenforschung Petroleum Industry Research Associates Pilot Research moored Array in the Tropical Atlantic Permanganate Oxidizable Carbon POLarization and Directionality of the Earth s Reflectances Princeton Ocean Model... 

Wid you realize that air turbulence is caused by the behaviour of gases Turbulence can be caused by changes in air pressure in the atmosphere. Airplanes are designed, however, to adjust to the behaviour of atmospheric gases. The combustion in the engines, the shape of the airplane, and the air mixture that passengers breathe are all designed to take gas behaviour into account. 

The amount of a given gas in water depends on its ability to react chemically with water molecules or to dissolve as a free molecule, on its partial pressure in the atmosphere, and on its vapor pressure it also depends on both temperature and the amount of dissolved salts. 

There are two species in this grouping— ammonia (NH3) and ammonium (NH4) with one valence state (—III) (Table 1). The primary species emitted to the atmosphere is NH3 produced during organic matter decomposition and emitted when the partial pressure in the soil, water, or plant is greater than the partial pressure in the atmosphere. It is the most common atmospheric gaseous base and, once in the atmosphere, can be converted to an aerosol in an acid-base reaction with a gas (e.g., HNO3) or aerosol (e.g., H2SO4) ... 

The active volcanoes of the Jovian moon lo release large quantities of sulfur and other materials (Spencer and Schneider, 1996) that recover the surface at a rapid rate and maintain a tenuous atmosphere. This sulfur is largely as sulfur dioxide, which is also found as condensate that covers some three-quarters of the surface. However, sulfur is also found as elemental sulfur, with perhaps traces of hydrogen sulfide (Russell and Kivelson, 2001 Zolotov and Fegley, 1998). Low pressures in the atmosphere of lo mean that sulfur can remain in seemingly exotic forms such as sulfur monoxide (SO), which has been calculated to have an SO/SO2 ratio of 3-10% (Zolotov and Fegley, 1998). Others suggest that OSOSO, and its cation, are likely present in the lo s atmosphere (Cacace et al., 2001). 

As discussed earlier, water has a direct influence on the resistance of microorganisms to dry-heat destruction. The destruction rate of spores is a function of the quantity of water in the cell at the time of heating. This water content is only constant under certain conditions and in most conditions, the moisture content of the cell can change so that the secondary variables cause confusion in analysis of results. The water vapor pressure in the atmosphere surrounding the cell determines the movement of water to or from microorganisms on surfaces. Research found that when the humidity in air passing over spores was increased from 0-0.2, the D value also increased by a factor of 100. Spores of intermediate moisture content with an RH between 0.1 and... 

In the case of oxides with variable valence state, the degree of densification may depend further on partial oxygen pressure in the atmosphere. For instance, spinel MgCr204 requires for its densification an O2 pressure lower than 10 Pa (Anderson, 1974). Maximum densities are attained at an oxygen pressure beyond which the spinel becomes unstable and volatilizes. 

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