Atmosphere lower regions

G. Mitri and co-workers calculated the minimum area of hydrocarbon lakes which would be necessary to preserve the relative methane humidity in the lower regions of the atmosphere. The result was surprising the calculations indicated that only between 0.002 and 0.2% of the total surface area of Titan would be required (Mitri et al., 2007). 

Notice how the temperature of the atmosphere changes with altitude. Close to the surface of the Earth, the temperature is about 20°C. The temperature falls to about — 55°C at 15 km and then rises again at higher altitudes. One reason that the stratosphere is warmer than lower regions of the atmosphere is the fact that solar radiation causes different chemical reactions at different altitudes. For example, these reactions result in a relatively stable concentration of ozone we call the ozone layer in the stratosphere. The reactions that produce ozone also release energy and, as a result, the temperature rises with altitude. 

The continuous vaporization of cosmic dust in the upper atmosphere leads to permanent metal atom layers at altitudes between 90-100 km. As pointed out in the introduction, the metals play an important role in the lower regions of the ionospheric region (see Fig. 2). The first manifestation of upper atmospheric metals was noticed early this century, when coarse spectra of the night sky revealed a line at 589.2 nm. In 1929, Slipher suggested that this emission line was due to sodium.Later studies refined the measurement to 589.3 nm, and tne identification of the Na-D emission line was definitely made. Shortly after, the first association of the Na-D line emissions in the nightglow with meteors entering the Earth s atmosphere was made by a number of authors.The actual chemical mechanism that can lead to optical emission of the Na-D line was first suggested by Chapman" ... 

Two additional processes besides carbon chemistry keep the atmospheric CO2 lower than it otherwise would be. One process is referred to as the solubility pump and the other as the biological pump. The solubility pump is based on the fact that CO2 is more soluble in cold waters. In the ocean, CO2 is —2 times more soluble in the cold mid-depth and deep waters than it is in the warm surface waters near the equator. Because sinking of cold surface waters in Arctic and Antarctic regions forms these mid-depth and deep waters, the formation of these waters with high CO2 keeps the CO2 concentration of the atmosphere lower than the average concentration of surface waters. 

The bar is a unit for measuring pressure, equal to the pressure exerted by Earth s atmosphere at sea level. The bar is commonly used to express positions within the atmosphere of Jupiter, Saturn, and some other planets. Low values, such as 0.1 bar, represent upper regions of the atmosphere, while high values, such as 100 bar, represent lower regions. The higher the bar value for a measurement, the deeper the level of the atmosphere represented.)... 

The Sandia code CONTAIN is a lumped parameter code with mechanistical models for simulating the physical and chemical conditions in the nuclear containment to predict hydrogen and steam concentration distribution as well as the consumption of H2 by respective combustion. Assuming a core meltdown accident and no vessel breach, i.e., no corrosion/concrete interaction, the code has predicted a thermally stratified containment atmosphere with relatively low temperatures in the central and lower regions which would permit steam condensation. Concerning H2 deflagration, CONTAIN predicts respective bums, if sprays are used for steam removal [56],... 

At 80 km, T — 200 K, at which 1.4 X 10 cm molecule s. The exponential term in (3.64) is <0.01 for r > 1.8 X 10 s (50 h). Thus the time needed for O to establish a steady-state concentration is much longer than that over which the solar intensity varies, and O is never in steady state at this altitude in the atmosphere. The reason why, at this altitude, 0( D) achieves a steady state and O does not, is based on the relative rates of the removal reactions. That for 0( D) is sufficiently fast that for O is too slow to keep up with the formation step. In the lower regions of the atmosphere, where the pressure is large, and hence the concentration of third bodies, M, is large, removal reactions for both O and 0( D) are, under all conditions, sufficiently fast that steady states are rapidly established for both species. 

The stratosphere is a layer of the Earth s atmosphere between 12 and 50 kilometres above the surface. The lower regions of the stratosphere (the ozone layer) contain around 90% of the atmospheric ozone at a concentration of less than 10 ppm. Ozone levels are maintained through a cycle of synthesis and breakdown reactions involving free radicals generated by the action of energy from UV-C and UV-B radiation (Table 14.8). 

The APIOOO does not need a containment spray system to cool the containment atmosphere, because this function is performed by the passive containment cooling system. The principal means of post-accident isotope control for the APIOOO relies on natural forces, like natural convection, condensation and conduction, to transfer decay heat from the lower regions of the containment to the containment walls, which are cooled (there is also a containment spray utilising the fire protection system (see Section 8.4.3.10), as a backup for this function. The resulting steam condenses onto the containment wall, and then returns to IRWST or to the containment sump by gravity. Through analysis and testing, it has been shown that the soluble and suspended isotopes move with the water, and thus finish up in the water in the IRWST or the lower portions of the containment. 

Fig. 5.3 Atmospheric ozone depletion (%) on August 1 of the same year as the Scenario II nuclear war. Negative values indicate ozone increases and show the opposite effects of NOx injections on ozone in the upper and lower regions of the atmosphere...

The term aquifer is used to denote an extensive region of saturated material. There are many types of aquifers. The primary distinction between types involves the boundaries that define the aquifer. An unconfined aquifer, also known as a phraetic or water table aquifer, is assumed to have an upper boundary of saturated soil at a pressure of zero gauge, or atmospheric pressure. A confined aquifer has a low permeabiUty upper boundary that maintains the interstitial water within the aquifer at pressures greater than atmospheric. For both types of aquifers, the lower boundary is frequendy a low permeabihty soil or rock formation. Further distinctions exist. An artesian aquifer is a confined aquifer for which the interstitial water pressure is sufficient to allow the aquifer water entering the monitoring well to rise above the local ground surface. Figure 1 identifies the primary types of aquifers. 

Effect of Pressure. The effect of pressure in VPO has not been extensively studied but is informative. The NTC region and cool flame phenomena are associated with low pressures, usually not far from atmospheric. As pressure is increased, the production of olefins is suppressed and the NTC region disappears (96,97). The reaction rate also increases significantly and, therefore, essentially complete oxygen conversion can be attained at lower temperatures. The product distribution shifts toward oxygenated materials that retain the carbon skeleton of the parent hydrocarbon. 

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