Atmospheric factors

Stanners have designed a test rig (Fig. 19.12) which provides results that can be correlated with actual atmospheric exposure data. The rig has been designed to investigate a wide range of alloying elements in a development programme on slow-weathering steels for which it was essential to have a rapid, reliable and reproducible test that incorporated the specific atmospheric factors responsible for rust formation. 

In many cases it will not be acceptable to relieve a two-phase reacting mixture direct to the atmosphere. Factors to be considered121 include ... 

In the UV, the atmospheric factors to be considered are total ozone amount, aerosol optical thickness and the atmospheric pressure. 

Since 1992 the two Italian stations of Rome, urban site (latitude 41.9° N, longitude 12.5° E, altitude 60 m), and Ispra, semi-rural site (latitude 45.8° N, longitude 8.6° E, altitude 240 m), collect regular continuous measurements of spectral UV (290-325 nm) irradiance by means of Brewer Spectrophotometry. The measured data are compared with the output of the STAR model (System for Transfer of Atmospheric Radiation) [1], STAR is a multiple scattering radiative transfer model which considers all atmospheric factors modulating UV radiation at ground (ozone, aerosol, clouds, pollutants, albedo, pressure, temperature, humidity) [2], The model involves combination of a radiative transfer code, an initialisation procedure and an integration scheme. 

H. Guttman, Effect of Atmospheric Factors on the Corrosion of Rolled Zinc, Metal Corrosion in the Atmosphere, STP 435, ASTM, Philadelphia, PA, 1968, pp. 223-239. 

The summer minimum at an altitude between 20 and 25 km. is probably caused by a higher reaching turbulence which brings more ozone down than can be produced photochemically. It is striking that between 25 and 30 km. there is no seasonal variation. Obviously photochemical and atmospheric factors have no great influence in this region or they compensate each other. 

Shaw, T. R. In "Atmospheric Factors Affecting the Corrosion of Engineering Metals" ASTM SPP 646, 1978. 

Guttman, H. (1968) Effects of atmospheric factors on rolled zinc. Atmospheric Corrosion of Metals, ASTM STP 767, American Society for Testing and Materials, 286-308. 

The aim of this section is to discuss the modifications of the atmospheric composition which can be related to the variations of the radiation balance and temperature observed in this century. We shall first deal with the relation between short-range modifications of atmospheric (stratospheric and tropospheric) composition and the transfer of incoming radiation. After this discussion, atmospheric factors influencing the absorption of infrared radiation emitted by the Earth s surface will be presented briefly. 

Figure 4-13a. Geometry for calculating the path length in a spherical atmosphere. Factor po(z0 = cosy is given by the ratio between the...

Resistance to changing weather conditions and atmospheric factors... 

Measurements of radon in soil are expressed in terms of levels in soil-gas. However, these measurements do not directly relate to rates of radon released to the atmosphere. Factors which affect radon soil-gas levels include radium content, soil porosity, moisture content, and density. Technically, measurement of soil-gas is difficult and there are few studies which report such data. 

Other atmospheric factors such as gaseous impurities in the air (e.g. sulfur dioxide, ammonia, carbon monoxide, ozone, carbon dioxide, halogen compounds, or formaldehyde) and solid impurities in the atmosphere (airborne dust, sand, and soot) result in an acceleration of aging processes in polymers. Whereas the effects of the gaseous impurities on polymers are mainly chemical in nature, the solid particles mostly cause abrasive damage to the plastic surface. 

Atmospheric factors PSF that influences actions due to weather. High winds, rain, snow or sleet can affect manual dexterity and make egress paths hazardous when traversing shppery sections. Extremely high winds negatively impact hearing and flexihihty of movement (DiMattia 2005). 

W. Ailor, in Atmospheric Factors Affecting the Corrosion of Engineering Metals, S. Coburn, editor, STP 646, American Society for Testing and Materials, Philadelphia, 1978, p. 129. 

Pourbaix diagram [3] maps out possible stable equilibrium phases of an aqueous electrochemical system and indicates that piue iron is passive at pH values from 9 to 12.5 to form iron hydroxide. Considering the interplay of atmospheric factors this diagram was used as guide to the steel dissolution process to form passivity on WS in laboratory. The passive films formed on pure iron are not so stable and consequently the passivation state of iron is not maintained for prolonged time periods [147, 148]. The mst layers of steels play a role as a barrier against corrosion, and their growth rate is decreased to a rate similar to that of the passive films, when suitable elements are added to the steel [149, 150]. 

German, G. (1978). Corrosion prevention with thermal-sprayed zinc and aluminum coatings. Proc. Anniversary Symposium, Atmospheric Factors Affecting the Corrosion of Engineering Metals, ASTM STP 646. ASTM, Philadelphia, pp. 74-82. 

Physical Causes - Heat, Cold and Other Atmospheric Factors... 

Important points concerning the atmospheric factors can be summarized as follows ... 

Paint coated materials are exposed primarily to the natural atmosphere. Consequently, paint adhesion is influenced by atmospheric factors, particularly moisture and water. All organic polymers and organic coatings are permeable to water. They differ only in the degree of permeability. Table 12.1 provides typical values for the permeability and the diffusion coefficient for water in a number of different polymers. 

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