Question

Which of the following statement is correct? (a) The region which is greatly affected by air pollution is troposphere. (b) The region which contains water vapour is troposphere. (c) Ozone layer is present in stratosphere. (d) All the above.

Short answer

All the above.

Step-by-step solution

Understanding Troposphere

The troposphere is the lowest layer of Earth's atmosphere and is where most weather events occur. It contains approximately 75% of the atmosphere's mass and is greatly affected by air pollution. It also contains water vapor.

Understanding Stratosphere

The stratosphere is the layer above the troposphere and contains the ozone layer, which absorbs and scatters ultraviolet solar radiation. The presence of the ozone layer is a key feature of the stratosphere.

Evaluating Statements

Now, let's evaluate each statement:(a) The region which is greatly affected by air pollution is troposphere. (True)(b) The region which contains water vapour is troposphere. (True)(c) Ozone layer is present in stratosphere. (True)

Conclusion

Since all three statements (a), (b), and (c) are true, the correct answer is (d) All the above.

Key concepts

Troposphere

The troposphere is the closest atmospheric layer to Earth’s surface. It extends from the ground up to about 8-15 kilometers high, depending on where you are on the planet.
One of its key characteristics is that it houses most of our weather events, such as rain, snow, and storms. This is because it contains most of the atmosphere's water vapor.
Additionally, the troposphere contains about 75% of the atmosphere’s mass. This dense layer of air makes it particularly susceptible to air pollution. Pollutants from factories, vehicles, and other sources get trapped here, affecting air quality and human health.
Furthermore, the temperature decreases as you go higher in the troposphere, making it cooler at the top than at the bottom.

Stratosphere

Sitting just above the troposphere, the stratosphere extends from about 15 to 50 kilometers above Earth's surface. Unlike the troposphere, this layer is relatively stable with less turbulence, making it ideal for high-altitude flights for airplanes.
A key feature of the stratosphere is the ozone layer. This layer absorbs and scatters the sun’s harmful ultraviolet (UV) radiation, protecting all living organisms below.
Temperatures in the stratosphere actually increase with height, which is the opposite of what happens in the troposphere. This temperature pattern helps create a separation, known as the tropopause, between these two layers.

Ozone Layer

The ozone layer is a special part of the stratosphere and is crucial for life on Earth. It contains a high concentration of ozone (O₃) molecules that absorb the majority of the sun’s harmful ultraviolet (UV) radiation.
Without the ozone layer, these UV rays would reach the Earth's surface, leading to skin cancers, cataracts, and other health issues in living beings. It also protects ecosystems and wildlife from excessive UV exposure.
It’s important to note that human activities have led to the depletion of the ozone layer. Chemicals like chlorofluorocarbons (CFCs) used in refrigeration and aerosols break down ozone molecules. Efforts such as the Montreal Protocol aim to reduce and eventually eliminate these harmful substances.

Air Pollution

Air pollution refers to harmful substances in the atmosphere that can pose risks to health and the environment. The troposphere is the layer most impacted by air pollution due to its proximity to human activities.
Common pollutants include:

• Particulate matter (PM)
• Nitrogen oxides (NOx)
• Sulfur dioxide (SO₂)
• Volatile organic compounds (VOCs)
• Carbon monoxide (CO)

These pollutants come from various sources like industrial processes, vehicles, agricultural activities, and natural events like wildfires.
Air pollution can lead to serious health problems, including respiratory and cardiovascular diseases. It also affects the environment by contributing to acid rain, harming wildlife, and reducing visibility. Implementing policies to reduce emissions and enhance air quality is essential to mitigate these impacts.