Under which layer of the Earth's atmosphere is the ozone layer found, which protects us from harmful ultraviolet rays?
Show answer & explanation
Correct answer: B
Explanation
Correct Answer
Stratosphere
Explanation
The ozone layer, which absorbs roughly 97% to 99% of the Sun's harmful, high-frequency ultraviolet (UV) radiation, is found within the Stratosphere. The stratosphere is the second major layer of Earth's atmosphere, located directly above the troposphere and right below the mesosphere.
The highest concentration of ozone ($O_3$) molecules is typically situated at an altitude between 15 and 35 kilometers above the Earth's surface, a region commonly referred to as the ozonosphere. In this layer, ozone is constantly formed and destroyed through a natural cycle driven by solar radiation, known as the Chapman mechanism. Ultraviolet light splits oxygen molecules ($O_2$) into individual atoms, which then combine with unbroken $O_2$ molecules to form ozone. By shielding the planet from dangerous UV-B and UV-C rays, this atmospheric blanket protects living organisms from severe consequences like skin cancers, cataracts, and cellular mutations.
Key Points
The troposphere is the lowest layer of the atmosphere where almost all human activity, weather phenomena, and cloud formations take place, but it contains only a tiny fraction of atmospheric ozone.
The mesosphere lies directly above the stratosphere, where temperatures drop drastically to the coldest levels in the entire atmosphere and most meteors burn up upon entry.
The exosphere represents the uppermost frontier of the atmosphere, gradually merging with the vacuum of outer space where air density is extremely low.
Important Questions and Answers
Question: Which international environmental treaty was signed in 1987 to phase out the production of ozone-depleting substances like Chlorofluorocarbons (CFCs)?
Answer: The Montreal Protocol was established to protect the ozone layer by regulating ozone-depleting chemicals.
Question: What is the specialized scientific unit used by meteorologists to measure the absolute thickness and concentration of the ozone layer?
Answer: The Dobson Unit (DU) is the standard unit of measurement for ozone column concentration.