In Earth atmosphere, the natural ozone layer that absorbs most of the Sun harmful ultraviolet radiation is mainly concentrated in which atmospheric layer?

Introduction / Context:
Ozone in the atmosphere plays a crucial protective role by absorbing a significant portion of the Sun harmful ultraviolet radiation, particularly UV-B. This region of enhanced ozone concentration is commonly called the ozone layer. Knowing where this layer is located within the structure of Earth atmosphere is important in environmental science, climate studies, and general knowledge. The atmosphere is divided into several layers, and this question asks you to identify the specific layer where ozone is most concentrated.

Given Data / Assumptions:

• Earth atmosphere is divided into layers such as the troposphere, stratosphere, mesosphere, thermosphere, and ionosphere (which overlaps some of these layers).
• Ozone is present in small amounts throughout the atmosphere but is highly concentrated in a specific region known as the ozone layer.
• The ozone layer is responsible for absorbing much of the Sun ultraviolet radiation.
• The question is about where this concentration is highest, not about ground level ozone pollution.

Concept / Approach:
The ozone layer is located primarily in the stratosphere, roughly between 15 and 35 kilometres above Earth surface. Within this region, the concentration of ozone is much higher than in other atmospheric layers, although still small in absolute terms. Ozone forms and decomposes through photochemical reactions involving oxygen molecules and ultraviolet light. While small amounts of ozone can exist in the troposphere, especially as a pollutant near the ground, the natural protective ozone layer that shields life from ultraviolet radiation is a feature of the stratosphere.

Step-by-Step Solution:
Step 1: Recall the basic order of atmospheric layers from the ground upwards: troposphere, stratosphere, mesosphere, thermosphere, and exosphere, with the ionosphere overlapping parts of the upper layers. Step 2: Remember that most weather phenomena occur in the troposphere and that commercial jets often fly at the lower stratosphere. Step 3: Identify that the maximum concentration of ozone, known as the ozone layer, lies in the stratosphere, typically between about 15 and 35 kilometres altitude. Step 4: Recognise that this stratospheric ozone strongly absorbs ultraviolet radiation and thus protects living organisms on the surface. Step 5: Conclude that among the given options, stratosphere is the correct atmospheric layer for the natural ozone layer.

Verification / Alternative check:
Environmental science texts and climate reports consistently show graphs of ozone concentration versus altitude, with a pronounced peak in the stratosphere. International agreements such as the Montreal Protocol were specifically concerned with protecting stratospheric ozone from depletion by chlorofluorocarbons. Although the ionosphere is associated with charged particles and radio communication, it is not the region defined by maximum ozone concentration. The mesosphere and thermosphere are too high and contain very little ozone. These cross checks confirm that the ozone layer is primarily a stratospheric feature.

Why Other Options Are Wrong:
The troposphere is the lowest layer where weather occurs and where we live; it contains only small amounts of ozone, often as a pollutant near ground level, not the protective ozone layer. The ionosphere is a region of ionised gases that overlaps the mesosphere, thermosphere, and exosphere but is defined by charged particles rather than ozone. The mesosphere is higher than the stratosphere and has very low ozone content. The thermosphere is even higher and is dominated by highly energetic particles and ionisation, not by ozone. Therefore, none of these layers match the main ozone concentration region.

Common Pitfalls:
Some students confuse the troposphere and stratosphere because they are adjacent layers, leading them to choose the wrong one. Others might pick the ionosphere because they associate it with radiation from the Sun, forgetting that its key feature is ionisation, not ozone. To avoid these mistakes, remember a simple phrase such as "Ozone shield in the stratosphere" to connect the ozone layer with the correct atmospheric layer.

Final Answer:
The natural ozone layer is mainly concentrated in the stratosphere of Earth atmosphere.