Question

The ozone layer __________. a. is getting thicker b. helps keep Earth warm c. is a layer in the deep ocean d. screens out UV radiation

Short answer

The ozone layer screens out UV radiation (option d).

Step-by-step solution

Understanding the Ozone Layer

First, we need to understand what the ozone layer is. The ozone layer is a region of the Earth's stratosphere that contains a high concentration of ozone (O₃) molecules. It plays a crucial role in protecting life on Earth.

Evaluating the Options

Let's analyze the given options: - a. 'is getting thicker' implies a change in the ozone layer's state. While efforts are being made to repair the ozone hole, this option isn't about the current function or purpose. - b. 'helps keep Earth warm' is inaccurate as the ozone layer primarily deals with UV radiation rather than temperature regulation. - c. 'is a layer in the deep ocean' is incorrect as the ozone layer is in the stratosphere, not the ocean. - d. 'screens out UV radiation' describes the primary function of the ozone layer to protect life by absorbing the majority of the sun's harmful ultraviolet radiation.

Selecting the Best Option

Among the options, we know that the crucial purpose of the ozone layer is to absorb and block ultraviolet (UV) radiation from the sun. Therefore, the option that directly describes its main function is the correct choice.

Conclusion

Based on our evaluation, option d. 'screens out UV radiation' is the most accurate description of the role of the ozone layer.

Key concepts

Ultraviolet Radiation

Ultraviolet radiation, often abbreviated as UV radiation, is a type of energy emitted by the sun. It's invisible to the naked eye but plays a significant role in various natural processes. The sun emits various kinds of energy that reach the Earth, including visible light, infrared rays, and UV radiation. UV radiation itself is classified into three types based on its wavelength: UVA, UVB, and UVC.

The shorter the wavelength, the more harmful the UV radiation, with UVC being the most dangerous. However, UVC is absorbed by the ozone layer and does not reach the Earth's surface. UVB is primarily responsible for sunburn and can damage DNA in living organisms, leading to skin cancer. UVA, while less intense, penetrates deeper into the skin and contributes to aging and long-term skin damage.

• UVA: Long-wave, less intense but penetrates deep.
• UVB: Medium-wave, causes sunburn and DNA damage.
• UVC: Short-wave, extremely harmful but absorbed by the ozone layer.

The ozone layer plays a vital role by filtering out the most harmful UV radiation, specifically UVC and most UVB, allowing life on Earth to thrive.

Stratosphere

The stratosphere is a layer of Earth's atmosphere situated above the troposphere and below the mesosphere. It extends from about 10 to 50 kilometers above Earth's surface. Unlike the troposphere, where weather changes occur, the stratosphere is remarkably stable. Temperature in this layer increases with altitude, a phenomenon due to the absorption of ultraviolet radiation by ozone.

The rise in temperature with altitude differentiates the stratosphere from the troposphere, where temperature decreases with height. This unique thermal structure is crucial for the formation and stability of the ozone layer within the stratosphere. The presence of the ozone layer within the stratosphere serves an essential protective function.

Some noteworthy characteristics of the stratosphere include:

• Stable air flow with few weather disturbances.
• Temperature inversion due to ozone absorption of UV radiation.
• Home to the protective ozone layer.

Consequently, understanding the stratosphere's role helps clarify why the ozone layer's location is strategic for shielding Earth from harmful ultraviolet radiation.

Ozone (O₃) Molecules

Ozone molecules are composed of three oxygen atoms and are denoted chemically as O₃. These molecules are not evenly distributed in the atmosphere; instead, they are highly concentrated within the ozone layer located in the stratosphere. Ozone plays a critical role in shielding life on Earth by absorbing most of the sun's harmful ultraviolet (UV) radiation.

O₃ molecules are formed when oxygen molecules () are split by UV light, allowing single oxygen atoms to combine with  molecules, creating ozone. This cycle of formation and destruction of ozone molecules entails a balance that enables the ozone layer to function effectively as a protective shield. Here's a breakdown of how O₃ molecules operate:

• Formation: UV radiation splits  into individual oxygen atoms.
• Combination: These individual atoms merge with  molecules to form O₃.
• Protection: Ozone absorbs UV radiation, preventing it from reaching Earth's surface.

Maintaining the concentration of O₃ is crucial, as a depleted ozone layer would result in increased UV radiation exposure, posing significant risks to ecosystems and human health.