The claim that solar radiation intensity increases at higher altitudes due to a thinner atmospheric layer is a matter of basic physics and common knowledge regarding atmospheric science, requiring no citation.
The claim is a well-established physical fact about atmospheric attenuation and altitude. None of the retrieved papers specifically target or measure the direct relationship between altitude and total solar radiation intensity as their primary thesis, making them tangential. As a foundational piece of common knowledge regarding solar irradiance, it does not require academic citation, resulting in a COMMON_KNOWLEDGE verdict with empty index arrays.