Terrestrial Radiation - 8.2.1 | 8. SOLAR RADIATION, HEAT BALANCE AND TEMPERATURE | CBSE 11 Fundamental of Physical Geography
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Introduction to Terrestrial Radiation

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0:00
Teacher
Teacher

Today, we're going to talk about terrestrial radiation. Can anyone tell me what happens to the solar energy that the Earth absorbs?

Student 1
Student 1

Doesn't the Earth just keep it all?

Teacher
Teacher

Good question, Student_1! The Earth doesn't keep all the energy; instead, it radiates a significant part back into the atmosphere as long-wave radiation. This process is essential for maintaining our climate.

Student 2
Student 2

So how much of the solar energy does the Earth actually reflect?

Teacher
Teacher

About 35% of incoming solar radiation is reflected back into space - that's called albedo, which plays a crucial role in our climate. Remember, 'A low albedo means more heat retention!'

Student 3
Student 3

And what happens to the rest of the energy?

Teacher
Teacher

Great question! The remaining energy, which is 65%, is absorbed by the Earth's surface and the atmosphere, heating them up and contributing to the long-wave radiation emitted.

Student 4
Student 4

Why is that long-wave radiation important?

Teacher
Teacher

The long-wave radiation warms the atmosphere and plays a significant role in maintaining the Earth's temperature. It's part of the heat budget - a balance of the energy coming in versus the energy going out.

Teacher
Teacher

So, to recap, terrestrial radiation involves the Earth absorbing sunlight and re-emitting it as heat to the atmosphere, essential for climate stability.

Heat Budget and Albedo

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0:00
Teacher
Teacher

Let's dive deeper into the heat budget. Who can explain what is meant by the heat budget of the Earth?

Student 1
Student 1

Isn't it how much heat the Earth gains and loses?

Teacher
Teacher

Exactly, Student_1! The heat budget is essentially a balance. The insolation received from the Sun and the terrestrial radiation emitted back into space must be equal for the Earth to maintain a stable temperature.

Student 2
Student 2

How does albedo factor into that?

Teacher
Teacher

Albedo is critical – it determines how much solar energy is reflected. For example, ice and clouds have high albedo and reflect a lot of energy, while forests have low albedo. When more energy is reflected, less is available for heating, impacting the heat budget.

Student 3
Student 3

Can you give an example?

Teacher
Teacher

Sure! In polar regions, the high albedo due to ice leads to lower temperatures as more solar energy is reflected. This keeps polar areas colder than tropical regions with lower albedo and more absorbed energy.

Teacher
Teacher

So, remember, 'Albedo affects absorption, influencing heat detection!'

Long-wave Radiation and Greenhouse Effect

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0:00
Teacher
Teacher

Now let’s discuss long-wave radiation and the greenhouse effect. Why is long-wave radiation important?

Student 1
Student 1

Because it heats the atmosphere, right?

Teacher
Teacher

Correct! Long-wave radiation heats the atmosphere, and greenhouse gases, such as CO2 and methane, trap this heat. Can someone give me an example of greenhouse gases?

Student 2
Student 2

Carbon dioxide is one.

Teacher
Teacher

Exactly! And this process, known as the greenhouse effect, helps keep the Earth warm. Can anyone tell me why we need this effect?

Student 3
Student 3

To maintain life, it keeps the Earth’s temperatures from getting too cold.

Teacher
Teacher

Great point! However, an excess of these gases can lead to too much heat being trapped, causing global warming. So, always remember, 'A balanced greenhouse is key for life.'

Introduction & Overview

Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.

Quick Overview

Terrestrial radiation refers to the heat emitted by the Earth's surface, which is essential for maintaining temperature balance in the atmosphere.

Standard

This section explains terrestrial radiation, highlighting how the Earth absorbs solar energy and re-emits it as long-wave radiation, which warms the atmosphere. The concepts of heat budget, albedo, and atmospheric interactions are also discussed.

Detailed

Terrestrial Radiation Summary

Terrestrial radiation is a key concept that describes how the Earth, after being heated by incoming solar radiation, emits heat back into the atmosphere in the form of long-wave radiation. This process is crucial for maintaining the Earth's heat balance. Here's a breakdown of the main points covered:

  1. Insolation Reception: Earth receives solar energy in short-wave forms, where approximately 65% of this energy is absorbed (51 units by the surface, 14 units by the atmosphere), and 35% is reflected back into space.
  2. Heat Emission: The Earth radiates energy as terrestrial radiation (51 units), with portions absorbed by atmospheric gases (like CO2) significantly impacting atmospheric temperatures.
  3. Heat Budget: The balance of incoming solar radiation and outgoing terrestrial radiation ensures that the Earth's average temperature remains stable. Albedo, which is the reflectivity of surfaces, plays an important role in this process.
  4. Long-Wave Radiation: The long-wave radiation emitted by the Earth is essential for heating the atmosphere, primarily due to its absorption by greenhouse gases.
  5. Global Impact: The heat from tropics is redistributed poleward, preventing extremes in temperature variations across different regions. The resulting balance maintains temperatures within a relatively stable range globally.

This section emphasizes the importance of terrestrial radiation within energy transfer processes and climate dynamics.

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Definitions & Key Concepts

Learn essential terms and foundational ideas that form the basis of the topic.

Key Concepts

  • Terrestrial Radiation: The process of the Earth's surface re-emitting absorbed solar energy as heat.

  • Heat Budget: The balance of incoming and outgoing energy that maintains stable global temperatures.

  • Albedo: The reflectivity of surfaces affecting how much solar energy is absorbed or reflected.

  • Long-wave Radiation: Energy released by the Earth that warms the atmosphere and is affected by greenhouse gases.

Examples & Real-Life Applications

See how the concepts apply in real-world scenarios to understand their practical implications.

Examples

  • In tropical regions with low albedo, more solar energy is absorbed leading to warmer temperatures compared to polar regions that reflect more sunlight.

  • A local area with many trees and less concrete will have a lower albedo, absorbing more heat and creating a warmer microclimate.

Memory Aids

Use mnemonics, acronyms, or visual cues to help remember key information more easily.

🎡 Rhymes Time

  • 'The Earth gets heat, but it must share, Through long waves it shines, warming the air.'

πŸ“– Fascinating Stories

  • Once upon a time, the Earth absorbed the sun’s warmth, but to keep balance, it decided to share its heat through a cozy blanket of long-wave rays with the atmosphere, ensuring harmony.

🧠 Other Memory Gems

  • Remember: A - Albedo, R - Reflectivity, H - Heat budget, G - Greenhouse gases. 'All Radiate Heat, Good for Earth!'

🎯 Super Acronyms

Remember 'HEAT' - 'Heat Emitted After Transfer' to recall terrestrial radiation process.

Flash Cards

Review key concepts with flashcards.

Glossary of Terms

Review the Definitions for terms.

  • Term: Terrestrial Radiation

    Definition:

    The heat emitted by the Earth's surface after absorbing solar energy.

  • Term: Insolation

    Definition:

    Incoming solar radiation received by the Earth.

  • Term: Albedo

    Definition:

    The percentage of solar energy reflected back into space.

  • Term: Heat Budget

    Definition:

    The balance between incoming solar radiation and outgoing terrestrial radiation.

  • Term: Longwave Radiation

    Definition:

    Energy emitted from the Earth to the atmosphere in long wavelengths.