The atmospheric green house effect is produced mainly by the absorption and re-emission of :

Question

Accepted Answer

The atmospheric greenhouse effect is primarily caused by the absorption and re-emission of infra-red radiations by the atmosphere. This process is crucial in maintaining the Earth's temperature and making it habitable. Here's a detailed explanation supporting Option 2 as the correct answer:

1. **Explanation for Option 2 (Correct Answer):**
   - The Earth's surface absorbs energy from the sun, primarily in the form of visible light. This energy is then re-emitted as infra-red radiation (heat). Greenhouse gases in the atmosphere, such as carbon dioxide, methane, and water vapor, absorb this infra-red radiation and re-emit it in all directions, including back towards the Earth's surface. This process traps heat in the atmosphere, leading to the warming effect known as the greenhouse effect. Without this natural greenhouse effect, the Earth's average temperature would be significantly lower, making it inhospitable for most current life forms.

2. **Why Option 1 is Incorrect:**
   - Visible light is not absorbed and re-emitted by the atmosphere in a way that contributes to the greenhouse effect. Instead, visible light passes through the atmosphere and is absorbed by the Earth's surface. The greenhouse effect is specifically related to the absorption and re-emission of infra-red radiation, not visible light.

3. **Why Option 3 is Incorrect:**
   - Ultra-violet rays are mostly absorbed by the ozone layer in the stratosphere and do not significantly interact with the ground in a way that contributes to the greenhouse effect. The greenhouse effect is concerned with infra-red radiation, not ultra-violet rays.

4. **Why Option 4 is Incorrect:**
   - While the atmosphere does absorb some ultra-violet radiation, this process is not related to the greenhouse effect. The absorption of ultra-violet radiation by the atmosphere primarily involves the ozone layer, which protects life on Earth from harmful UV radiation but does not contribute to the warming effect associated with the greenhouse effect. The greenhouse effect is specifically due to the absorption and re-emission of infra-red radiation.

In summary, the greenhouse effect is a result of infra-red radiation being absorbed and re-emitted by greenhouse gases in the atmosphere, making Option 2 the correct answer.