Which gas is primarily found in the upper atmosphere and plays a vital role in protecting the Earth?

The gas that is primarily found in the upper atmosphere and plays a critical role in protecting the Earth is ozone. Ozone resides in the stratosphere, forming a layer that absorbs the majority of the sun's harmful ultraviolet (UV) radiation. This protective layer is essential for life on Earth, as excessive UV radiation can lead to skin cancer, cataracts, and other adverse effects on wildlife and ecosystems.

Ozone's presence in the upper atmosphere is particularly significant because it acts as a shield, allowing only a fraction of UV rays to reach the surface. Without this protective layer, life as we know it would be severely threatened. In contrast, while gases like carbon dioxide and oxygen are present in the atmosphere, they do not provide the same degree of protection from UV radiation. Nitrogen, although abundant, is inert and does not play a direct role in shielding the planet from harmful solar radiation.