Which layer of the atmosphere prevents ultraviolet rays from reaching the…

Earth's atmosphere is divided into distinct layers by altitude and composition. Within the stratosphere lies the ozone layer — a band rich in ozone (O₃) molecules that absorbs the Sun's harmful high-energy ultraviolet radiation, chiefly UV-B and UV-C, through photochemical reactions that convert it into heat.

Because this ozone-rich shield sits specifically within the stratosphere, the stratosphere is the atmospheric layer that blocks most of this harmful ultraviolet radiation before it reaches the earth's surface.

Why the other layers do not fit

• Troposphere: the lowest layer, home to weather such as clouds, rain, and wind; it does not contain the concentrated ozone band that provides this protective shielding.

• Ionosphere: a layer of ionised particles far higher up, formed when the Sun's extreme-ultraviolet and X-ray radiation ionises its gases; it is valued for reflecting radio waves for long-distance communication, not for shielding the surface from UV-B/UV-C.

• Mesosphere: mostly transparent to incoming solar radiation; its hallmark feature is that meteoroids burn up here due to friction, and it is the coldest of all the atmospheric layers.