The increasing amount of carbon dioxide in the air is slowly raising the temperature of the atmosphere, because it absorbs
the infrared part of the solar radiation
Understanding Carbon Dioxide and Atmospheric Warming
The question asks why the increasing amount of carbon dioxide in the air is causing the temperature of the atmosphere to rise. This phenomenon is primarily due to the way carbon dioxide interacts with energy radiated by the Earth.
The Role of Carbon Dioxide in the Atmosphere
Carbon dioxide (\( \text{CO}_2 \)) is a trace gas in the Earth's atmosphere, but it plays a crucial role in regulating the planet's temperature. It is one of the key greenhouse gases. Greenhouse gases are atmospheric gases that absorb and emit radiant energy within the thermal infrared range.
Analyzing the Interaction with Radiation
Let's look at how carbon dioxide interacts with different types of radiation mentioned in the options:
- Water vapour absorption: While water vapour is also a greenhouse gas and absorbs heat, the question specifically asks about carbon dioxide's effect. Carbon dioxide's warming effect is distinct and significant, even considering water vapour. Carbon dioxide does not absorb water vapour; it absorbs radiation.
- Ultraviolet part of solar radiation: The Earth's atmosphere, particularly the ozone layer, absorbs most of the harmful ultraviolet (UV) radiation from the sun. Carbon dioxide is not a primary absorber of UV radiation.
- All the solar radiations: Solar radiation includes various parts of the electromagnetic spectrum, such as visible light, ultraviolet, and infrared. Carbon dioxide does not absorb all parts of solar radiation. Visible light, for example, passes through carbon dioxide largely unimpeded, which is why the sun's light reaches the Earth's surface.
- Infrared part of the solar radiation: The sun emits radiation across a spectrum, including some infrared. However, the most significant interaction of greenhouse gases like carbon dioxide is with the infrared radiation emitted by the Earth's surface after it has been warmed by the sun. The Earth absorbs solar radiation (mostly visible light) and then re-emits energy as infrared radiation (heat). Carbon dioxide molecules are very effective at absorbing this outgoing infrared radiation.
The Greenhouse Effect Explained
Here’s a simplified explanation of the greenhouse effect involving carbon dioxide:
- Solar radiation from the sun reaches the Earth.
- The Earth's surface absorbs much of this solar radiation and warms up.
- The warmed Earth's surface then emits energy back out into space in the form of infrared radiation.
- Greenhouse gases, like carbon dioxide, methane, and water vapour, in the atmosphere absorb this outgoing infrared radiation.
- These greenhouse gases then re-emit the infrared radiation in all directions, including back towards the Earth's surface.
- This re-emission of infrared radiation back towards the Earth's surface traps heat, causing the atmosphere and the Earth's surface to warm up. This is similar to how a greenhouse traps heat.
The increasing amount of carbon dioxide in the atmosphere means more of the outgoing infrared radiation is absorbed and re-emitted back towards the Earth, leading to a gradual increase in the average temperature of the atmosphere. Therefore, carbon dioxide warms the atmosphere because it absorbs the infrared part of the radiation emitted by the Earth.
| Gas | Primarily Absorbs | Effect on Temperature |
|---|---|---|
| Oxygen (\( \text{O}_2 \)) and Nitrogen (\( \text{N}_2 \)) | Very little radiation in IR range | Minor direct warming |
| Ozone (\( \text{O}_3 \)) | Ultraviolet (UV) and some Infrared (IR) | Warms stratosphere (UV), contributes to greenhouse effect (IR) |
| Water Vapour (\( \text{H}_2\text{O} \)) | Infrared (IR) | Strong greenhouse gas |
| Carbon Dioxide (\( \text{CO}_2 \)) | Infrared (IR) | Significant greenhouse gas, increasing concentration causes warming |
Based on this understanding, the increasing amount of carbon dioxide in the air raises the temperature of the atmosphere because it absorbs the infrared part of the radiation, specifically the outgoing infrared radiation emitted by the Earth.
Revision Table: Key Concepts
| Term | Definition/Relevance |
|---|---|
| Carbon Dioxide (\( \text{CO}_2 \)) | Greenhouse gas, absorbs infrared radiation. |
| Atmosphere | Layer of gases surrounding Earth, traps heat via greenhouse effect. |
| Infrared Radiation | Heat radiation emitted by Earth, absorbed by greenhouse gases. |
| Greenhouse Effect | Process where gases trap heat in atmosphere, warming the planet. |
Additional Information: Climate Change and Greenhouse Gases
The increase in atmospheric carbon dioxide is largely due to human activities, primarily the burning of fossil fuels (coal, oil, and natural gas), as well as deforestation and industrial processes. This increased concentration of \( \text{CO}_2 \) enhances the natural greenhouse effect, leading to a phenomenon known as global warming or climate change.
Other important greenhouse gases include methane (\( \text{CH}_4 \)), nitrous oxide (\( \text{N}_2\text{O} \)), and fluorinated gases. While carbon dioxide is not the most potent greenhouse gas per molecule, it is the most significant contributor to climate change because of the large quantities emitted and its long lifetime in the atmosphere.
Understanding which types of radiation different gases absorb is fundamental to understanding atmospheric science and climate change.
Important Questions from Atmosphere
In the cities of our country, which among the following atmospheric gases are normally considered in calculating the value of Air Quality Index?
1. Carbon dioxide
2. Carbon monoxide
3. Nitrogen dioxide
4. Sulfur dioxide
5. Methane
Select the correct answer using the code given below.
A layer in the Earth's atmosphere called Ionosphere facilitates radio communication. Why?
1) The presence of ozone causes the reflection of radio waves to Earth.
2) Radio waves have a very long wavelength.
Which of the statements given above is/are correct?
The jet aircrafts fly very easily and smoothly in the lower stratosphere. What could be the appropriate explanation?
1) There are no clouds or water vapour in the lower stratosphere.
2) There are no vertical winds in the lower stratosphere.
Which of the statements given above is/are correct in this context?
Which one of the following is associated with the issue of control and phasing out of the use of ozone-depleting substances?
Which of the following statements with reference to Surface inversion of temperature is/are correct? 1. It causes instability in the lower layers of the atmosphere. 2. This inversion commonly lasts for a few hours until the Sun comes up.
