Atmospheres Surface pressure

The planet Mars is smaller than the Earth its diameter is 6,762 km, compared with the Earth s 12,760 km. Our neighbour planet has only a very thin atmosphere (surface pressure 0.005-0.010 atm), so its surface can easily be observed. The atmosphere consists of the following (volume percentages given) ... 

Radok U, Allison 1, Wendler G (1996) Atmospheric surface pressure over the interior of Antarctica. Antarct Sci 8 209-217... 

The atmospheric surface pressure on Venus is 90 bar and is composed of 96% carbon dioxide and approximately 4% various other gases. Given a surface temperature of730 K, what is the mass of carbon dioxide present per cubic centimeter at the surface ... 

The triple point is at a temperature of 273.16 K (0.01 °C1 by convention, and at a pressure of 611.73 Pa. This pressure is quite low, about /lee of the normal sea level barometric pressure of 101,325 Pa. The atmospheric surface pressure on planet Mars is remarkably close to the triple point pressure, and the zero-elevation or "sea level" of Mars is defined by the height at which the atmospheric pressure corresponds to the triple point of water. 

The planet Pluto as well as many satellites in the outer Solar System, such as Charon, Triton, and others belong to the group of relatively small objects with significant amounts of ices on the surface (see also Schmitt et al, 1998). The atmospheric surface pressure is then controlled by the surface temperature, the vapor pressure of the frozen volatiles, and the escape rate of the gases. Even Mars, with its CO2 polar caps, may be included in this group. Pluto and Charon are discussed together with comets and asteroids in Chapter 7. 

Fig. 9.2.5 Calculated Martian atmospheric surface pressure as a function of latitude and local time during global dust storm conditions. A tidal model with measured atmospheric temperature fields as input was used to obtain the results shown (Pirraglia Conrath, 1974).

At times when the surface pressure gradient is weak, resulting in light winds in the atmosphere s lowest layers, and there is a closed high-preSsure system aloft, there is potential for the buildup of air pollutant concentrations. This is especially true if the system is slow-moving so that light winds remain in the same vicinity for several days. With light winds there will be little dilution of pollutants at the source and not much advection of the polluted air away from source areas. 

FIG. 28 Normalized steady-state diffusion-limited current vs. UME-interface separation for the reduction of oxygen at an UME approaching an air-water interface with 1-octadecanol monolayer coverage (O)- From top to bottom, the curves correspond to an uncompressed monolayer and surface pressures of 5, 10, 20, 30, 40, and 50 mN m . The solid lines represent the theoretical behavior for reversible transfer in an aerated atmosphere, with zero-order rate constants for oxygen transfer from air to water, h / Q mol cm s of 6.7, 3.7, 3.3, 2.5, 1.8, 1.7, and 1.3. (Reprinted from Ref. 19. Copyright 1998 American Chemical Society.)... 

The boundary conditions are that (1) at the moving boundary ( ) the solution is saturated with salt with a corresponding concentration of water (Cs) and (2) at the disk/atmosphere surface the concentration of water is governed by the equilibrium vapor pressure in the chamber to give a water concentration of C0. 

Because of the weight of the column of gases above any point on the earth s surface, the atmosphere exerts pressure at every point on the earth s surface. This pressure, which is variously known as atmospheric, barometric, or air pressure, varies according to the altitude above sea level and the weather conditions (see Textbox 70). 

Fig. 2.6 The main components of a typical weakly reducing primeval atmosphere as a function of the altitude above the Earth s surface. The mole fraction refers to the mixing ratio of the atmospheric mixture at an assumed surface pressure of one atmosphere. After Kasting (1993)... 

As the planet acquires a volatile molecule inventory it begins to develop an atmosphere, and in the case of the Earth this also includes the extensive circulation of water in the hydrosphere. The weight of the volatiles trapped in the atmosphere of a planet leads to a mean surface pressure, po, given by ... 

In order to calculate the partial pressure of carbon dioxide, it is necessary to figure the total dissolved carbon and alkalinity as well. I consider three reservoirs—atmosphere, surface sea, and deep sea—as illustrated in Figure 5-1. I distinguish between the concentrations in the surface and deep reservoirs by using a terminal letter. v for the surface reservoir and d for the deep reservoir. 

Figure 9. VIS Multiplot of absorbance of a monolayer of diacetylene lipid (5) vs. polymerization time. Constant surface pressure 10 mN m l 20°C N2 atmosphere.

The most useful type of standard state is one defined in terms of a small number of molecules per unit area of adsorbent surface. In an attempt to have a definition analogous to that for three-dimensional matter—one atmosphere at any temperature—Kemball and Rideal (12) defined a standard state with an area per molecule of 22.53T A.2 where T is the absolute temperature. This corresponds to the same volume per molecule as the three-dimensional state if the thickness of the surface layer is 6A. In terms of surface pressure it corresponds to 0.0608 dynes/cm. for a perfect two-dimensional gas at all temperatures, and as such the definition may be extended to cover condensed films. 

The hypothesis that liquids in contact with charcoal were actually compressed on the surface of the solid was originally suggested by Lagergren Bihang till k. Svenska Vet. Akad. Handl. 24, ii. 4, 1898) who assumed the existence of surface pressures of the order of 10,000 atmospheres. Lamb and Coolidge (J.A.G.S. XLII. 1146,1920) considered that the net heat of adsorption was due to compression alone and that with charcoal the compressive force was substantially the same for all liquids, viz. 37,000 atmospheres. A similar conclusion was arrived at by Harkins and Ewing. 

Fig. VIII—13. Temperature profile of the atmosphere of Venus. The surface corresponds to 6055 km from the center of Venus. (M) is the number of molecules per cm3. The surface pressure is 88 bars and the temperature is 750°K. Venus is covered with dense clouds (probably sulfuric acid droplets). After McEwan and Phillips (20), reprinted by permission of Edward Arnold Ltd.

Geopressured Zones. A test well in a geopressure zone was drilled some years ago in Tigre Lagoon in the coastal marshes of southern Louisiana Known as Edna Delcambre 1, this well produced at a rate of np to 10,000 barrels of water per day from a sandstone aquifer some 12,600 feet (3840 meters) below the surface. Pressure at that depth is nearly 11,000 pounds per square inch (748 atmospheres) and the temperature is 116°C. Quite an elaborate manifold system is requited to collect the gas. The water is disposed by forcing it by... 

The activities of Mg++ and Ca++ obtained from the model of sea water proposed by Garrels and Thompson have recently been confirmed by use of specific Ca++ and Mg++ ion electrodes, and for Mg++ by solubility techniques and ultrasonic absorption studies of synthetic and natural sea water. The importance of ion activities to the chemistry of sea water is amply demonstrated by consideration of CaC03 (calcite) in sea water. The total molality of Ca++ in surface sea water is about 10 and that of COf is 3.7 x 1C-4 therefore the ion product is 3.7 x 10 . This value is nearly 600 times greater than the equilibrium ion activity product of CaCO of 4.6 x 10-g at 25°C and one atmosphere total pressure. However, the activities of the free 10ns Ca++ and COj = in surface sea water are about 2.3 x 10-3 and 7.4 x 10-S, respectively thus the ion activity product is 17 x 10 which is only 3,7 rimes greater than the equilibrium ion activity product of calcite. Thus, by considering activities of sea water constituents rather than concentrations, we are better able to evaluate chemical equilibria in sea water an obvious restatement of simple chemical theory but an often neglected concept in sea water chemistry. 

Specific surface ranges from 1 to 1000 square meters/gram. It is most often measured by adsorption of nitrogen at Its atmospheric saturation pressure (-195.8 C), with analysis of the data by the BET adsorption equation (problem P6.01.02). Pore diameters of common catalysts range from 10 to 200 Angstroms (10-8 cm) problem P6.01.01 discusses such data. Porosity of a bed of... 

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