Which UV is almost never observed in nature due to atmospheric absorption?

Which UV is almost never observed in nature due to atmospheric absorption?

• A. UVA
• B. UVB
• C. None
• D. UVC

Answer: (D)

Short-wavelength ultraviolet light is largely blocked by Earth’s atmosphere. The ozone layer and other atmospheric gases absorb the highest-energy UV radiation, especially the UVC range (about 100–280 nm). By the time sunlight would reach the surface, UVC is effectively gone, so natural UVC exposure at ground level is essentially nonexistent. In contrast, UVA and UVB do reach the surface, with UVA penetrating deeply and UVB contributing to sunburn and vitamin D production. That’s why the UV almost never observed in nature due to atmospheric absorption is UVC.

Short-wavelength ultraviolet light is largely blocked by Earth’s atmosphere. The ozone layer and other atmospheric gases absorb the highest-energy UV radiation, especially the UVC range (about 100–280 nm). By the time sunlight would reach the surface, UVC is effectively gone, so natural UVC exposure at ground level is essentially nonexistent. In contrast, UVA and UVB do reach the surface, with UVA penetrating deeply and UVB contributing to sunburn and vitamin D production. That’s why the UV almost never observed in nature due to atmospheric absorption is UVC.