Vertical West Research Articles

UV Index experimental values on vertical surfaces

UV erythemal irradiance (UVER) has been studied on a horizontal plane and on vertical surfaces with different orientations in Valencia, Spain. The evolution of the solar noon value and the maximum daily value over a year has been analysed from the instantaneous UVER taken every five minutes on the horizontal plane and on vertical surfaces with north, south, east and west orientations. The annual evolution of these values shows a sinusoidal form for all planes except for the vertical south plane with maxima in spring and autumn. The UV Index (UVI) on these planes was also determined. The percentage of coincidence of the UVI at solar noon and of the maximum daily UVER values, considering differences of 1 or 0 units, is 87% on the horizontal plane, 100% on the vertical north plane, 92% on the vertical south plane, 77% on the vertical east plane and 75% on the vertical west plane. We have compared the UVI of the vertical plane with the horizontal one by means of linear regressions. All planes show very good correlations except for the vertical south plane, which shows no correlation with the horizontal plane for the middle days of the year due to its particular geometry with respect to the Sun's apparent path. Finally, the annual cumulative UVER doses related to each phototype for the horizontal and vertical planes were calculated. It was noticed that the dose over a year on the horizontal plane doubles the dose on the vertical south plane, which is the one that receives the maximum dose. Copyright © 2011 Royal Meteorological Society

The insolation on vertical surface having different directions in the Kingdom of Bahrain

The daily total global ( H T) and diffuse ( H DIF) solar radiation, measured at Bahrain International Airport, Kingdom of Bahrain, (latitude 26° 13″N and longitude 50° 39″E), had been recorded, analyzed, and studied. The mean hourly values of H T and H DIF on horizontal and vertical surfaces (facing North, South, East and West) have been averaged to daily and monthly radiation. The monthly average global solar radiation on a horizontal, vertical north, vertical east, vertical south and vertical west was 22.5, 4.0, 9.4, 11.9 and 11.3MJ/m 2, respectively. The monthly average of the diffuse ( H DIF) and direct ( H DIR) insolation was found 6.9 and 15.4MJ/m 2, respectively. The direct radiation represents, on average, 69.4% of the total insolation while the diffuse represents 30.6% of it. In comparing these values with previously measured total direct and diffuse in 1996 at the University of Bahrain, Isa Town campus, Kingdom of Bahrain (latitude 26° 20″N and longitude 50° 5″E), we found that the previous records give less percentage of H DIR/ H than the recent ones by 10.7%, while the opposite is true for H DIF/ H, as the recent is larger by 24.5%. This might be attributed either to the difference in the accuracy of the sensors or to the reduction in the atmospheric pollution, bearing in mind that the distance between the two places does not exceed 50 km. The total insolation incident on vertical west-facing surface was found to, on average, be larger than east facing by 20.2%, and as much as by 50.8% in January and larger by only 11.9% in July.

Internal structure and emplacement of the Papoose Flat pluton: An integrated structural, petrographic, and magnetic susceptibility study

The Papoose Flat pluton of eastern California is commonly cited in the geologic literature as a classic example of a “forcibly” emplaced pluton, although the relative importance attributed to magmatic versus tectonic processes in controlling the structural evolution of the pluton has been controversial. Reexamination of this Late Cretaceous (83 Ma) pluton, using a combination of new structural, petrographic, microstructural, and anisotropy of magnetic susceptibility (AMS) data on the pluton–wall-rock system, has shown that the pluton is an inclined and internally zoned tabular structure, assembled by forcible intrusion of successive pulses of magma at a crustal depth of 12–15 km. Initial pluton formation involved magma ascent in a vertical west- northwest–striking feeder dike, which was arrested at a stratigraphically controlled mechanical discontinuity in the overlying Cambrian metasedimentary rocks, leading to formation of a southwest-dipping sill. Subsequent sill inflation, accompanied by horizontal infilling from the feeder dike at the base of the sill, resulted in deformation and vertical translation of previously emplaced magma pulses and local raising of the sill roof, facilitated by thermal weakening as the wall-rock temperatures progressively rose during emplacement of successive magma pulses. Cooling from the roof of the pluton downward resulted in cessation of vertical inflation on the west side of the pluton and promoted lateral expansion toward the northeast and floor depression below the eastern part of the pluton. We have been unable to document any regional-scale structures (e.g., of equivalence to similar-age synplutonic strike-slip shear zones in the Sierra Nevada batholith to the west) that may have controlled emplacement of the Papoose Flat pluton. However, this fact does not preclude the likelihood that the country rocks were subjected to a regional deviatoric stress field at this time; indeed, tectonic overpressuring was probably essential for producing sufficiently high magma pressures for laccolith formation at this midcrustal level. Simple thermal modeling, using microstructural and thermobarometric data, indicates that the total duration of emplacement of the pluton did not exceed 30 000 yr. This rapid emplacement rate may explain why the pluton appears to be anorogenic even though it was emplaced during a period of regional- scale deformation.