Introduction

DS1.1 All parts of Earth interact

How energy from the sun interacts with Earth plays an important role in the creation of Earth’s climates and biomes. The different ways energy is moved around Earth create the weather patterns that we see.

This section will teach you what a biome is and why it is important to the diversity of life on Earth. You will learn the different parts within the biosphere and how they interact. You will study in detail the movement of the sun’s energy and the relationship between that energy and the different parts of Earth. Finally, you will study each type of biome found on Earth and their interactions.

  Targets

By the end of this section, you will be able to

DS1.2 The biosphere

1. describe the major characteristics of the three parts of the biosphere: the atmosphere, the hydrosphere, and the lithosphere
   

DS1.3 The sun

2. identify the sun as the source of all energy on Earth and analyze, in general terms, how that energy interacts with Earth
   

DS1.4 Arctic living

3. describe a biome as an open system and explain how climate affects the lives of people and other species
   

DS1.5 Cause of the seasons

4. describe the relationship between solar energy and the seasons and explain how thermal energy movement through the atmosphere and hydrosphere affects climate

DS1.6 Comparing biomes

5. relate the characteristics of two major biomes to radiant energy and climate

  Introduction

D1.1 Earth’s energy comes from the sun

This lesson will take you on a journey, starting with the sun and ending here on Earth. During this journey, you will learn where all of Earth’s energy comes from and what different parts of the earth do with that energy. We will also look at Earth’s biosphere and its three components. This lesson will give you the knowledge base you need to understand how climates, seasons, and biomes are formed.

  Targets

• describe the major characteristics of the biosphere, atmosphere, hydrosphere, and lithosphere
• identify the sun as the source of all energy on Earth
• explain the net radiation budget of Earth

  Watch This

  The Biosphere

DS1.2 The biosphere

Earth is a unique planet because, as far as we know, Earth is the only planet where living things survive. The biosphere makes this possible. It is a thin layer of air, land, and water on or near the earth’s surface. This thin layer is where all life on Earth exists as well as the environments where that life lives. Anything outside of the biosphere is considered to be uninhabitable. This means that nothing living can survive outside of the biosphere.

Each part of the biosphere—the air, land, and water—has a specific name and characteristics.

The Atmosphere

D1.2 Parts of the atmosphere

The atmosphere is the name given to the layer of air found in the biosphere. The atmosphere is a mix of nitrogen, oxygen, and small amounts of other gases. This layer takes up the space from the earth’s surface to approximately 800 km above the earth’s surface. The atmosphere itself can be split into four layers: the thermosphere, mesosphere, stratosphere and troposphere. Image D1.2 shows a fifth layer that we will not study in this course. The majority of the gases found in the atmosphere are concentrated in the stratosphere and troposphere.

Have you ever heard the term “thin air”? This expression is used to describe air where there is less oxygen present. As you get farther up in the atmosphere, the concentration of oxygen becomes less and less. Even within the stratosphere and troposphere, humans can sense a noticeable difference in the makeup of the air as they get farther from the earth’s surface. This is because humans find it more difficult to breathe as they get farther from the earth’s surface.

Organisms living in the atmosphere are generally found in the troposphere, as this is the layer closest to Earth’s surface. There have been clumps of microorganisms found in the stratosphere, but nothing living has been found in the mesosphere or thermosphere.

D1.3 Mount Everest is the tallest mountain on Earth

  Did You Know?

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D1.4 Machu Picchu, 2430 metres above sea level

If we travel too far up into the atmosphere, we can actually become quite sick. This sickness is caused by low amounts of oxygen in the air and can occur any time you are 2 438 metres or higher above sea level. People who are planning to travel to or exercise in areas of high altitude need to train and prepare their bodies.

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The atmosphere is mostly made of nitrogen (N₂) and oxygen (O₂). They make up 78% and 21%, respectively. The remaining 1% of the atmosphere is made up of many other gases, including but not limited to argon (Ar), carbon dioxide (CO₂), methane (CH₄), neon (Ne), and helium (He). 

©Wikimedia Commons
D1.5 Gases in the atmosphere

The Hydrosphere

D1.6 The Hydrosphere

The hydrosphere is the name given to the water found in the biosphere. The water in the hydrosphere can be found as a liquid, as water vapour, or as ice. This water is generally found on or near Earth’s surface and includes oceans, lakes, rivers, streams, underground reservoirs, clouds, humidity, and moisture in the air. Interestingly, about 97% of the water found on Earth is in the form of salt water. This is interesting because most living organisms require fresh water to survive.

Some scientists consider the frozen water on Earth to be an additional category of water called the cryosphere.

Since Earth is 70% water and only 30% land, the hydrosphere is a large part of the biosphere. Most of the organisms on Earth require water to survive and so the hydrosphere is tied very closely to life on Earth. Many organisms, from algae to whales, live in one form of the hydrosphere or another. The hydrosphere also plays an important role in how the sun’s energy is distributed.

D1.7 Earth is 70% water

The Lithosphere

D1.8 The Lithosphere

The lithosphere is the name given to the land found in the biosphere. It is made of rocks, minerals, and elements, and many organisms call the lithosphere home. The lithosphere contains Earth’s crust that forms the land and the bottom of the sea. Remember, the earth itself is made of many different layers from the center of the earth to the surface of the earth. These layers are called the mantle and the core. The lithosphere includes the top layer of the earth’s mantle as well as the crust.

Atmospheric dust can also be part of the lithosphere. Atmospheric dust is solid particles that can be non-living matter from Earth’s crust or living particles such as microorganisms and pollen. Only the non-living particles are considered part of the lithosphere.

  Digging Deeper

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Earth’s mantle makes up a very large portion of the planet. It is an amazing 2 900 km thick and makes up 84% of Earth’s total volume. Go to the following link for more information on this topic. https://www.nationalgeographic.org/encyclopedia/mantle/

Learn More

D1.9 Earth’s structure

  The Components of the Biosphere Interact

D1.10 All the parts of the biosphere interact

It is important to note and to understand that the three components (and each component of those three components) are constantly interacting with one another. It is through this interaction that the atmosphere, hydrosphere, and lithosphere form the biosphere. Each component is not found separate from the other components, but rather, all the components tend to be mixed together. For example, water vapour is found in the atmosphere, and a really muddy river or lake is a mixture of both the lithosphere and the hydrosphere.

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  Practice Questions

1. Complete the following chart:
   
   

   Part of the Biosphere	What It Contains	How It Supports Life	One Other Fact from Your Readings
   atmosphere
   lithosphere
   hydrosphere

   
   
   Check your work.
   

   Part of the Biosphere	What It Contains	How It Supports Life	One Other Fact from Your Readings
   atmosphere	It is the air above the earth’s surface,  which includes the thermosphere, mesosphere, stratosphere, and troposphere. It contains nitrogen and oxygen as well as other gases.	It provides the oxygen that living organisms need to survive and contains the warmth needed for survival.	Most of the gases and all of life are found in the stratosphere and troposphere (mostly troposphere). They ozone layer is found in the stratosphere.
   lithosphere	It is Earth’s crust (land and the bottom of the sea) and the top layer of the mantel. It also contains the non-living particles in the atmospheric dust found in the atmosphere.	It provides land for organisms to live on and feed off of.	It extends 100 km below Earth’s crust, into the mantle. It is mainly warmed by solar energy but also by Earth’s core.
   hydrosphere	It contains water in all three states (vapour, liquid, and ice) and includes clouds in the atmosphere and underground reservoirs.	It provides water for organisms to live in or drink.	97% of the water on Earth is salt water. The remaining 3% includes all the rivers, lakes, streams, snow, ice, and glaciers. It is mostly warmed by the sun but also by Earth’s core.

   
   

2. In your own words, define the term “biosphere.”
   
   
   Check your work.
   

   Your answer should be a variation of the following: The biosphere contains all the living things on Earth and the environment that supports them. It includes all the air, land, and water on Earth.
   
   
   

  The Sun

D1.11 Abstract of waves

Solar energy travels to Earth by electromagnetic waves and is then used in many different ways. About a quarter of the solar energy received by Earth is reflected back into space. Of the solar energy that is absorbed by Earth, a small portion gets converted to food energy through photosynthesis and the rest of it is converted to thermal energy. Remember from Unit C,  thermal energy is heat or the energy a substance has due to the kinetic energy (movement) of its particles. The more kinetic energy the particles have, the warmer the substance is.

Different regions on Earth receive different amounts of solar energy due to their location on Earth and the angle Earth sits at. We will study this in more detail in Lesson 3.

Recall from Unit C that there are many different forms of energy on Earth. All of these forms of energy can be traced back to the sun. The sun’s energy that reaches Earth is known as radiant energy. This type of energy is transmitted as electromagnetic waves. This means that the energy travels from one point to another through almost any material in waves that we cannot see.

D1.13 Temperatures rise

  Digging Deeper

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D1.12 The electromagnetic spectrum

There are many forms of electromagnetic waves, including infrared radiation, microwaves, X-rays, ultraviolet rays, and more. All of these forms put together create the electromagnetic spectrum. Go to the following link for more information about this spectrum.

Learn More

Did You Know?

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D1.14 Solar panel farm

The sun provides 100 000 times more energy than all other sources of energy combined! That is a lot of energy.

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  Practice Questions

1. How is solar energy used once it reaches Earth?
   
   
   Check your work.
   

   Most of the solar energy is converted to thermal energy once it reaches Earth. A small amount of it is converted to food energy through photosynthesis.
   
   
   
2. What is the source of all energy on Earth?
   
   
   Check your work.
   

   The sun!
   
   
   

  Net Radiation Budget

D1.15 Solar energy is reflected and absorbed

When solar energy reaches Earth, it can either be reflected or absorbed by the particles of matter.

Solar energy is short wave radiant energy.  As it passes through the atmosphere it can be reflected by clouds and bounced back into space.  A small amount may be absorbed by dust and converted into thermal energy. 
some is used by plants for photosynthesis.  As solar energy arrives at the surface, some is reflected by snow and water back into space, but about half is absorbed.

Solar energy absorbed at the Earths surface heats the the surface.  In other words, increases the amount of kinetic energy (motion) of the particles that make up the Earth.  Any warm matter will radiate infrared radiation.  Infrared radiation is long wave radiation that interacts with gases in the atmosphere differently that solar radiation does.  Greenhouse gases, like carbon dioxide, water vapour and methane, can absorb infrared radiation and gain kinetic energy.  These warm molecules then emit radiation in all directions.  Overall, half will radiate upwards into space and be lost from Earth, but half will radiate downwards and send energy back to Earth.

So Earths atmosphere does not much affect solar radiation arriving on Earth, but it does affect infrared radiation leaving it.

Solar radiation and the infrared radiation sent back to earth by greenhouse gases is incoming radiation.  Solar radiation reflected by clouds and snow, and Infrared radiation escaping to space are outgoing radiation.  The net radiation budget is the difference between the amount of incoming solar radiation and outgoing radiation emitted from the biosphere. The incoming solar energy includes all the solar energy that reaches Earth’s surface, while the outgoing radiation includes the energy that has been re-emitted by the earth’s surface and atmosphere.

Some of this outgoing radiation will be reabsorbed by the gases in the atmosphere and will become part of the incoming solar energy again.

© NASA, via Wikimedia Commons 
D1.16 Net radiation budget of Earth

Figure D1.16 shows how different parts of the biosphere affect the net radiation budget. You will notice that these percentages are slightly different than the ones in your textbook, because this is a more up-to-date image.

When solar energy enters Earth’s atmosphere,

• 48% of it is absorbed by the surface
• 23% of it is absorbed by the atmosphere
• 29% of it is reflected back into space
• 23% of this is reflected by the clouds and atmosphere.
• 6% is reflected by Earth’s surface.

On average, all the incoming radiation is eventually re-emitted back into space and becomes part of the outgoing radiation.

When this thermal energy is emitted,

• 70% is re-emitted from the atmosphere and Earth’s surface
• 9% is re-emitted by clouds.
• 50% is re-emitted by the atmosphere.
• 11% is re-emitted by Earth’s surface.
• 25% is emitted by phase changes in the hydrosphere (water changing from liquid to solid to gas)
• 5% is emitted by global winds

The net radiation budget for Earth is always very close to zero. Incoming radiation always closely matches the outgoing radiation. This helps keep Earth’s overall temperature stable and unchanging. Net radiation budgets that are not zero mean that the average amount of energy on Earth is changing, and that means climate change.

Changes in climate are natural.  Species evolve or become extinct as climate changes.  Human civilization is based on the relatively mild climate that we now enjoy.  We fear that if climate change is too rapid for our civilization to adapt to, many people would suffer as our human systems, like agriculture, struggle to adapt.

It is important to note while Earth as a whole has a net radiation budget of zero, different regions of Earth will not. These differences in regions will equal out to create an overall net radiation budget of zero.

  Did You Know?

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D1.17 Atmospheric dust off Africa

The most common theory around the extinction of the dinosaurs says that a large asteroid collided with Earth. This collision sent a large amount of dust into the atmosphere, severely altering the climate. The dust blocked the sun for weeks, possibly months, killing plants and disrupting the food chain. What would be the effect on the global temperature if sunlight was blocked and prevented from reaching the earth’s surface?

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  Practice Questions

1. What value should Earth’s net radiation budget have? What happens if that value changes?
   
   
   Check your work.
   

   Earth’s net radiation budget should have a value of zero. If that value changes from zero, then the global temperature of Earth will either increase (when the value is positive, there is more incoming radiation) or decrease (when the value is negative, there is less incoming radiation) until the net radiation budget becomes zero again.
   
   
   
2. What happens to solar energy that is absorbed by the biosphere? What happens to the solar energy that is reflected by the biosphere?
   
   
   Check your work.
   

   Solar energy that is absorbed by the biosphere will either be converted into food energy through photosynthesis or it will be converted into thermal energy (which is the kinetic energy of the substance’s particles). It will also be re-emitted as thermal energy.
   
   Solar energy that is reflected by particles in the biosphere will be either absorbed by other particles in the biosphere or reflected back into space.
   

3. Which part of the biosphere re-emits the most thermal energy back into space?
   
   
   Check your work.
   

   The atmosphere re-emits the most thermal energy back into space. It re-emits 50% of all the thermal energy being re-emitted.
   
   
   

  Conclusion

© NASA, via Wikimedia Commons
D1.16 Net radiation budget of Earth

All energy on Earth originates with the sun. Once that energy reaches Earth, it can be absorbed by particles in the biosphere to be used in photosynthesis or converted into thermal energy or it can be reflected back into space. No matter what happens with the energy when it first reaches Earth, it is eventually re-emitted or reflected back into space. The amount of energy that reaches Earth is always equal to the amount of energy that is sent back into space.

The biosphere itself consists of all living things found on Earth as well as their environments. The biosphere can be split into the atmosphere, hydrosphere, and lithosphere. While we can classify different parts of the biosphere into those three parts, it is important to remember that all three parts of the biosphere are constantly interacting and mixing together. Parts of the hydrosphere are found in the lithosphere and in the atmosphere, and parts of the lithosphere can be found in the atmosphere and the hydrosphere.

In the next lesson, we will start to look at how solar energy is used to create climate and biomes within the biosphere.

D1.18 All parts of the biosphere interact

  Interactive Activity

Molecules and Light © PhET

This simulation will help you understand the absorption and reflection of solar radiation by different gases in the atmosphere. This simulation will focus on infrared radiation—the part of solar radiation that is converted to thermal energy.

• Procedure
  
• Analysis

1. Click on the play icon to open the simulation. The simulation can also be found at https://phet.colorado.edu/sims/html/molecules-and-light/latest/molecules-and-light_en.html
2. Make sure the flashlight is set to infrared (the rest should be greyed out) and carbon monoxide is highlighted.
3. Set up an observation table in your notes similar to the one below.
   
   

   Gas	Reflected	Absorbed

   
   

4. Turn on the flashlight by moving the slider to the right.
5. Observe what happens to the particles of gas and the infrared light. What does it mean when the particles start to move?
   
   
   Check your work.
   

   The particles have absorbed the infrared radiation and converted it to thermal energy. Remember, thermal energy is the kinetic energy of particles; the more the particles move, the hotter they are.
   

© pHet
D1.19 Flashlight

6. What is happening when the infrared radiation changes direction?
   
   
   Check your work.
   

   The infrared radiation is being reflected.
7. Record carbon monoxide in your chart and check off if the radiation was reflected, absorbed, or both.
8. Change the gas to nitrogen and observe what happens. Record your observations in your chart.
9. Complete step 8 for each gas in the list.
10. Please return to the top of this page and click on analysis to complete the analysis questions.
    

Here is a completed observation chart.

Check your work.

Gas	Reflected	Absorbed
carbon monoxide (CO)	yes	yes
nitrogen (N2)	no	no
oxygen (O2)	no	no
carbon dioxide (CO2)	yes	yes
water (H2O)	yes	yes
nitrogen dioxide (NO2)	yes	yes
ozone (O3)	yes	yes

1. Which gases did not react to the infrared light?
   
   
   Check your work.
   

   nitrogen and oxygen
2. Why is this significant?
   
   
   Check your work.
   

   Our atmosphere is mostly made up of nitrogen and oxygen. Since infrared radiation is the radiation that is converted to thermal energy, this shows that without clouds (water vapour), atmospheric dust, and other items or substances in the atmosphere, all the heat would reach Earth’s surface and all of the thermal energy emitted from Earth’s surface would be lost back to space. It also shows the importance of the other gases found in our atmosphere, even though they are present in very small amounts. These gases help to capture some of the infrared radiation coming in from space and being re-emitted by Earth, playing a big part in keeping Earth’s temperature stable.
3. According to the net radiation budget, 48% of the incoming solar radiation is absorbed by Earth’s surface. Explain what this does to the particles that make up Earth and how this helps to keep Earth’s surface warm.
   
   
   Check your work.
   

   You will use this answer in your Formative Assessment D1.

4.1 Assignment

Unit 4 Formative Assessment Lesson 1