Photochem Photobiol. 2011 Nov-Dec;87(6):1474-5. doi: 10.1111/j.1751-1097.2011.00980.x. Epub 2011 Aug 25.
The objective of this communication is to present the calculated ratio between UVA and UVB irradiance from sunrise to sunset and under a number of weather conditions. UVA plays an important role in the sun spectrum and a lot of attention has been paid lately regarding the protection of people from UVA. Solar spectra were collected in Kuwait City located at 29.3° North latitude (similar to that of Houston, TX) over a period of 8 months and under various weather conditions. Spectra were collected from 260 nm to 400 nm in 2 nm increments for solar elevation angles from 10° to 90° using a calibrated Optronics Laboratories OL-742 Spectroradiometer. The measurements reported in this study the ratio of UVA (320-400 nm) to UVB (280-320 nm) in solar terrestrial radiation remains essentially constant and equal to 20 for the part of the day when the solar elevation is greater than 60°. Consequently the value of the ratio of solar UVA/UVB should be considered as equal to 20 for studies in photobiology and photomedicine. When the wavelength limiting the range of UVA and UVB is 315 nm (i.e. UVB: 280-315 nm and UVA: 315-400 nm) the ratio of UVA to UVB becomes equal to 41.
本通讯的目的是介绍从日出到日落以及在多种天气条件下计算的 UVA 和 UVB 辐照度比值。UVA 在太阳光谱中起着重要作用，最近人们非常关注保护人们免受 UVA 的伤害。在科威特市（位于北纬 29.3°，与德克萨斯州休斯顿相似），在 8 个月的时间内，在各种天气条件下收集了太阳光谱。使用经过校准的 Optronics Laboratories OL-742 分光辐射计，从 260nm 到 400nm 以 2nm 的增量收集了太阳仰角从 10°到 90°的光谱。本研究报告的测量值表明，在太阳仰角大于 60°的白天，太阳日地辐射中 UVA（320-400nm）与 UVB（280-320nm）的比值基本保持不变，等于 20。因此，在光生物学和光医学研究中，太阳 UVA/UVB 的比值应视为 20。当 UVA 和 UVB 的波长限制范围为 315nm 时（即 UVB：280-315nm，UVA：315-400nm），UVA 与 UVB 的比值等于 41。
