Weathering front

Vertical air motions affect both weather and the mixing processes of importance to air pollution. Upward vertical motions can be caused by lifting over terrain, lifting over weather fronts, and convergence toward low-pressure centers. Downward vertical motions can be caused by sinking to make up for divergence near high-pressure centers. One must know whether the atmosphere enhances or suppresses these vertical motions to... 

It is known that the line-source model employed can be rather sensitive to perturbations caused by outside influences such as the daily atmospheric temperature cycle or passing weather fronts (e.g. Austin, 1998 Gehlin, 1998 ... 

The oldest profile (CBAC 215) was preserved beneath Paleocene lake sediments. The least weathered saprock in this profile (59 m beneath the unconformity) has a REE pattern very similar to North American shale composite (NASC). The light REE show marked relative depletion in the upper part of the profile and enrichment near the weathering front. Cerium shows marked enrichment at depth (Fig. 2). 

Time variations in wind power are determined by passage of weather front systems. Typical passage of fronts over Denmark has a pattern exhibiting similar conditions over periods of a few days. This has implications for the amount of energy storage that would remove the mismatch between variable wind power production and demand. Lulls are followed by periods of high winds with delays of typically 3-6 days and very rarely over 12 days. 

When water, as in a pond or lake, is healed by warm air above it, it remains stable, does not move, and forms a warm layer of w ater on (op of a cold layer, Consider a deep lake (1 = 0.6 W/m K,c = 4.179 kJ/kg K) that is initially at a uniform temperature of 2°C and has its surface tempeiature suddenly increased to 20°C by a spring weather front. The temperature of the water 1 m below the surface 400 hours after this change is... 

Figure 3.6 Schematic representation of the downward advancement of the weathering front, showing the relative changes in abundances (shaded) of the major lateritic components, Si and Fe, during profile evolution.

This process comprises dissolution of alumino-silicate minerals, and is the basis for much of the discussion concerning the development of saprolites and associated weathering products. Although conditions at the weathering front may initially favour the formation of micaceous clays (e.g. chlorite, vermiculite) and smectite, small quantities of gibbsite may also be formed, and, eventually, kaolinite can come to dominate those free-draining profiles where there is an adequate water supply. 

Idnurm and Schmidt, 1986 Acton and Kettles, 1996). Elsewhere, magnetostratigraphy (the record of dated reversals in the Earth s magnetic field) has been applied to trace the timing of downward progression of the weathering front (e.g. Pillans, 1997 Theveniaut and Freyssinet, 1999). 

In certain cases, the desired manipulated variable for a particular process cannot be directly adjusted. Distillation columns can be particularly sensitive to sharp changes in ambient conditions due to weather fronts or thundershowers, since both of these cases can cause significant increases in the reflux subcooling. Equating the heat lost by the condensing vapor to the heat required by the subcooled reflux results in the following equation ... 

Air mass and weather front terminology were developed in Norway during World War I. Norwegian meteorologists were unable to get weather reports from the Atlantic theater of operations consequently, they developed a dense network of weather stations that led to impressive advances in atmospheric modeling that are still being used. 

Variable Vapour Return Line Pressures and Passing Atmospheric Weather Fronts... 

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