Solar irradiation sunlight

Exposure to solar irradiation (sunlight) may alter their chemical integrity and in due course some physical properties such as mechanical strength (e.g. brittleness) or color (e.g. fading) as well. Additives like industrial ultra violet (UV)-absorbers, hindered amine light stabilizers, radical scavengers and antioxidants are incorporated or applied in these products to effectively reduce or delay such radiation induced deteriorations. 

Sonnen-. of the sun, sun, solar, helio-. -auge, n. adularia. -bahn, /. ecliptic, -belichtung, /. exposure to sunlight, solar irradiation, insolation. 

DNA strongly absorbs UV radiation, especially mid-range UVB (290 to 320 nm) radiation. Two major DNA lesions are induced following UV exposure, pyrimidine dimers and 6-4 pyrimidine-pyrimidone photoproducts. Because the action spectrum (induction of a biological activity as a function of wavelength) for erythema closely matches the action spectrum for pyrimidine dimer formation, DNA is believed to be the chromophore for sunburn.6 Pyrimidine dimer formation, or more properly, the failure to adequately repair dimers after solar irradiation is also the primary cause of sunlight-induced skin cancer formation.7-8... 

For example, the solar photocurrent spectrum of a titania nanotube array photoanode calculated using relahon (3.6.23) is given in Fig. 3.25. The solar irradiance P (k) for the calculation is taken from Fig. 3.19. The total photocurrent that can be obtained from this electrode when exposed to global sunlight is... 

Earth s deserts receive 250-300 W/m2 of solar irradiance. If solar eneigy could be used with 10% efficiency, 4% of the sunlight falling on the deserts would provide all the energy used in the world in 2000. The solar cell17 described here has a conversion efficiency close to 7%. 

The handsheets impregnated with quinone model compounds were photolyzed in an Oriel 1000 W Solar Simulator. The Solar Simulator uses a xenon arc lamp to simulate the solar spectrum and was fitted with an air mass 1.5 global filter to model the average wavelength distribution of solar irradiation in the continental United States. An exhaust fan provided air circulation to minimize heating of the sample. The spectral distribution of the solar simulator is approximately equivalent to natural sunlight. 

Figure 9.1 Solar irradiance reaching the top of the Earth s atmosphere (AM(O) sunlight) and the sea level for different solar angles of 0°, 30°, 60° 85°, and 90°...

Fig. 17.7 Inactivation of E. coli by sunlight in a CPC photoreactor. The insert contains the UV (continuous line) and total (dashed line) solar irradiation measured during the period of the experiment. 25th (a) and 26th (b) September 2003, in Lausanne, Switzerland. Dark control for samples that corresponds to 0, 1, 2, and 3h of the illumination exposure. Conditions VT0T = 35 L, recirculation rate = 20.5 L min-1, illumination time = 3 h (a) and 5 h (b), natural pH. Type of water LLW. The bars show the SD of four samples...

AM (0) sunlight The solar irradiance in space just above the earth atmosphere (air mass, AM, zero). Also called extraterrestrial global irradiance. 

AM (1) sunlight The solar irradiance traversing the atmosphere when the sun is in a position perpendicular to the earth surface. Also called terrestrial global irradiance. 

As discussed earlier, the rate constant of the direct photoreaction can be calculated according to Equation 3.16, using the quantum yield and the sunlight intensity. Values for the average solar irradiance for clear skies at midday 7.k (photon cm-2 s 1 (2.5 nm) ) at 2.5-nm bandwidths over the relevant wavelength range of 297.5 to 320 nm as a function of season are available in the published literature only for 40°N (Leifer, 1988). On the other hand, day-average solar irradiance data are available for all latitudes (Zepp and Cline, 1977). The ratio of the 40°N values was used to estimate the midday irradiances for all other latitudes expressed for 2.5-nm bandwidths as U, in millieinstein cm-2 min 1 (2.5 nm)-1 Ux is therefore equivalent to 4 AA, in Equation 3.16, which now becomes... 

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