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A UV index reading of 3 to 5 means moderate risk of harm from unprotected sun exposure. Stay in shade near midday when the sun is strongest. If outdoors, wear sun-protective clothing, a wide-brimmed hat, and UV-blocking sunglasses. Generously apply broad spectrum SPF 50+ sunscreen every 1.5 hours, even on cloudy days, and after swimming or ...
Halogen lamps with fused quartz envelopes are used as inexpensive UV light sources in the near UV range, from 400 to 300 nm, in some scientific instruments. Due to its black-body spectrum a filament light bulb is a very inefficient ultraviolet source, emitting only a fraction of a percent of its energy as UV, as explained by the black body ...
Shortwave radiation (SW) is thermal radiation in the optical spectrum, including visible (VIS), near-ultraviolet (UV), and near-infrared (NIR) spectra. There is no standard cut-off for the near-infrared range; therefore, the shortwave radiation range is also variously defined.
The latest TikTok tanning trend involves monitoring the UV index and timing sunbathing sessions to when it's high, but experts say that exposing yourself to strong ultraviolet rays is a bad idea.
Most stars are actually relatively cool objects emitting much of their electromagnetic radiation in the visible or near-infrared part of the spectrum. Ultraviolet radiation is the signature of hotter objects, typically in the early and late stages of their evolution. In the Earth's sky seen in ultraviolet light, most stars would fade in prominence.
Spots from two sequential cycles co-exist for several years during the years near solar minimum. Spots from sequential cycles can be distinguished by direction of their magnetic field and their latitude. The Wolf number sunspot index counts the average number of sunspots and groups of sunspots during specific intervals. The 11-year solar cycles ...
The amount of penetration of UV relative to altitude in Earth's ozone. Next in frequency comes ultraviolet (UV). In frequency (and thus energy), UV rays sit between the violet end of the visible spectrum and the X-ray range. The UV wavelength spectrum ranges from 399 nm to 10 nm and is divided into 3 sections: UVA, UVB, and UVC.
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