Lesson 5 Thermal Energy and Climate

  Introduction

D5.1 Clouds over coastal mountains in BC

In this lesson, we will look at how thermal energy is transferred through the atmosphere and the hydrosphere. We will discuss how thermal energy travels from areas of high thermal energy to areas of low thermal energy and how this movement helps to create climates. These factors help to even out the amount of thermal energy each area of Earth retains.

This lesson will also review the biomes we have studied and look at how these new factors help to create them. We will also look at the topography (for example, how close the biome is to mountains or large bodies of water) and how it affects the climate of each biome.

Once these factors have been studied, this course will have covered the main factors that create climates and biomes on Earth. Now that we have studied how climate is created, we can start to look at climate change.

  Targets

• describe how thermal energy is transferred through the atmosphere and through the hydrosphere from areas of high thermal energy to areas of low thermal energy
• describe how radiant energy, climatic factors, and topography affect the biomes

  Watch This

  Thermal Energy and the Atmosphere

D5.2 Wind blowing the seeds off a dandelion

Remember, thermal energy transfer is the movement of thermal energy from areas of high thermal energy to areas of low thermal energy. In the previous section, we discussed how the closer to the equator a location is, the more insolation or radiant energy from the sun that location will receive. The farther a location is from the equator, the less insolation that location will receive. In fact, each pole receives very little insolation compared with the equator. So how does life survive at these poles? They must be very cold, right?

In fact, Earth does a great job of evening out these levels of insolation. The equator and each of the poles will never be equal, but the excess thermal energy is shared. The thermal energy that gathers at the equator due to the high amount of insolation is transferred through the atmosphere to areas that are cooler. Here are the factors that transfer the thermal energy through the atmosphere.

Coriolis Effect

D5.3 North–south convection currents

Wind on Earth is caused by convection. Remember, convection is the movement of hot and cold fluids as a current. Please watch this video for a review of convection.

As the cool air warms up, it becomes less dense and begins to rise, moving away from the surface of Earth toward space. As the hot air begins to cool, it becomes denser and begins to sink back down toward Earth’s surface. The hot air at the equator cools as it moves up toward space and away from the equator; after which it starts to sink. As it sinks, it pushes the cold air along, replacing the warm air that rose. As the cold air is pushed down toward Earth’s surface and the equator, it warms up and begins to rise away from Earth’s surface again. This pushes the air in front of it away from Earth’s surface and toward the poles, continuing the cycle.

If the Earth were not spinning, this would create a continuous convection current going from each pole to the equator. Image D5.3 shows these convection currents in each hemisphere. It is important to note the air moves in both altitude and latitude.

Air pressure also plays a part in these winds. Air pressure is the pressure caused by a large mass of air above any location on Earth. The more cold air above a location, the greater the air pressure, as cold air is denser and so has more mass, causing it to fall toward Earth’s surface. The greater air pressure then pushes the air away from that location back toward the equator. At the equator, the warm air rises toward space, causing very low air pressure, providing a space for the cold air being pushed in from the high pressure. The movement of the cold air pushes the warm air toward the poles.

The Coriolis effect occurs because the Earth is spinning. This effect causes the winds to be pushed in a more westerly direction, rather than directly north and south. Air or wind in the Northern Hemisphere is deflected right and left in the Southern Hemisphere. If you have a wind travelling from the North Pole toward the equator, the Earth would be spinning beneath the wind. If you are heading south from the North Pole, Earth is spinning to the left, beneath you, so you would end up to the right (or west) of your original goal.

If you are travelling from the South Pole toward the equator, the Earth is spinning to the right, beneath you. This means that you would end up to the left (or west) of your original goal. In both cases, the wind is being deflected toward the west; in the Northern Hemisphere, the winds are traveling south, so west is to the right, while in the Southern Hemisphere, the winds are travelling north, so west is to the left. Image D5.5 shows the Coriolis effect and how it deflects the winds in the Northern and Southern Hemispheres.  

D5.5 Coriolis effect 

  Digging Deeper

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D5.4 Sun vs. snow

Air pressure has a large effect on our weather. A warm, sunny day is generally seen when there are higher air pressures, and cold, rainy, cloudy or snowy days are seen when there are lower air pressures. Go to the following link to find out why. https://weatherworksinc.com/news/high-low-pressure

Learn More

  Read This

Please read pages 372 and 373 in your Science 10 textbook. Make sure you take notes on your readings to study from later. You should focus on what the Coriolis effect is and how it works. Remember, if you have any questions or you do not understand something, ask your teacher!

Global Wind Patterns

D5.6 Thermal transfer occurs from hot areas to cold areas

The convection currents and the Coriolis effect we just discussed form the global wind patterns. These patterns transfer thermal energy from areas where there is lots of thermal energy (such as the equator) to areas with less thermal energy (such as the North and South Poles).

At the equator, the winds tend to blow from the northeast if you are in the Northern Hemisphere or southeast if you are in the Southern Hemisphere. These winds are called the trade winds and are caused by the convection currents and the Coriolis effect.

Between the latitudes of 30˚ N and 60˚ N (Location A on image D5.7) or 30˚ S and 60˚ S (Location B on image D5.7), some of the air begins to sink because it has cooled and become denser. As it sinks, it starts to move back toward the equator, while the air that has not cooled enough yet, continues away from the equator. As the warm air continues away from the equator, it is pushed west due to the Coriolis effect. This leaves a hole for the cold air from the north to rush in. As the cold air moves into the hole created by the warm air, it is deflected east. Due to the pressure difference, the wind that heads east is much stronger than the wind heading west, so overall, the winds at these latitudes tend to head east and are called westerlies (because the blow from the west).

A similar phenomenon happens a bit farther from the equator, except the winds head west and blow from the east. At 60˚ N and 60˚ S (the Arctic and Antarctic circles), any warm air left is cooled, sinks down, and begins to travel back toward the equator. Due to the Coriolis effect, this wind travelling back to the equator is pushed west (coming from the east). These winds are called easterlies because they blow from the east.

Image D5.7 shows these three different winds in different colours. The colours orange and purple show the trade winds, red shows the westerlies, and blue shows the easterlies.

D5.7 Global wind patterns

  Read This

Please read page 374 in your Science 10 textbook. Make sure you take notes on your readings to study from later. You should focus on how each of the three global wind patterns is formed. Remember, if you have any questions or you do not understand something, ask your teacher!

  Watch This

Global Atmospheric Circulation © YouTube Keith Meldahl 

Watch this video for a great explanation on the convection currents that cause wind and how these convection currents create the global wind patterns.

Jet Stream

© By Lyndon State College Meteorology, via Wikimedia Commons
D5.8 The jet streams

Large land masses, such as continents, and large bodies of water can also affect wind patterns. These factors create friction in the lowest part of the atmosphere—the troposphere. This means winds in this level cannot move as fast. Winds that occur in the stratosphere—the next layer of the atmosphere after the troposphere—can move much faster as there is much less friction. These winds are called jet streams due to the speed at which they move.

There are several jet streams on Earth. Where they are and how many there are change depending on the season in each hemisphere, but in general, there are normally two to three jet streams in each hemisphere. They are also formed by the convection currents, so during cooler months, they tend to be closer to the equator and move more quickly. In the warmer months, they tend to move away from the equator and move more slowly. As the jet streams change, they can cause severe weather, such as storms and cyclones. They can also affect the wind patterns in the troposphere and so are important when predicting weather changes.

  Read This

Please read pages 374 and 375 in your Science 10 textbook. Make sure you take notes on your readings to study from later. You should focus on what jet streams are and how they are formed. Remember, if you have any questions or you do not understand something, ask your teacher!

  Did You Know?

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D5.9 Airplane wing

Jet streams can be helpful in air travel, as they can cause a flight to move much faster than it normally would. Jet streams can also cause a flight to move much slower, and they can cause turbulence. Pilots try to use jet streams when they are helpful and avoid them if they are not.

  Digging Deeper

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D5.10 Normal Year/La Niña Year

You might have heard the terms “El  Niño” and “La Niña,” but have you ever wondered what they mean? Both are complex weather patterns that are due to a change in the winds over the South Pacific Ocean. In Alberta, El Niño years tend to be much warmer than normal, while La Niña years tend to be colder with more snow. Go to the following link for more information about El Niño and La Niña.

Learn More

  Practice Questions

1. Print off the following map to draw on. Collect three different-coloured pens, pencils, or crayons and draw the following onto your map:
   
1. the rotation of Earth—colour 1
2. the convection currents without the Coriolis effect—colour 2
3. the deflection of the Coriolis effect for each hemisphere—colour 3
   
   
   Check your work.
   

   
   

   
   

   Caption: D5.11 Convection currents
   

   
   
   
   
2. Print off another copy of the map. Using the same three colours, or a different set, draw the following on your second map:
1. the trade winds—colour 1
2. the westerlies—colour 2
3. the easterlies—colour 3
   
   
   Check your work.
   

   
   

   
   

   Caption: D5.12 Global winds
   

   
   
   
   
3. How do all of these winds affect the thermal energy at different locations on Earth?
   
   
   Check our work.
   

   The winds transfer thermal energy from areas of high thermal energy to areas of low thermal energy. This means they carry the thermal energy from the equator north or south toward the poles. As the air cools, it sinks and makes its way back to the equator to absorb more thermal energy to bring north or south. In this way, the winds help to even out the thermal energy over Earth.
   

  Thermal Energy and the Hydrosphere

D5.13 Convection current in the ocean

The hydrosphere helps to transfer thermal energy from areas where there is lots of thermal energy to areas where there is less. A large part of this transfer occurs through the currents in the ocean. Just like wind, the ocean currents are caused by convection.

As ocean water moves north, it cools and freezes.  When sea ice forms, the salt is left out of the ice, making ocean water more salty.  This cold, salty water is more dense, so it sinks.  This can be thought of as the pump that drives ocean currents.

Cold water sinks and tends to more towards the equator.  Warm, less dense water moves on the surface to replace the water that sunk. As it moves towards the poles, it releases thermal energy into its surroundings, affecting the climate of those places. The ocean can move a lots of heat because it has a high specific heat capacity.  And little energy from the ocean is required to change air temperature because it has a high specific heat capacity.

Surface currents are then affected by wind patterns and the Coriolis effect.

When thinking about thermal energy being transferred in the hydrosphere, you will want to remember the affects the specific heat capacity, heat of fusion, and heat of vaporization have on climate.

Surface Currents

These surface currents in the oceans are caused by the winds we studied, such as the trade winds, on the previous page.  The surface currents do not follow the exact path of these winds that cause them, because the continents get in the way. Large land masses get in the way of the currents and tend to cause the current to circle back on it. You can see this effect in image D5.14. Notice how the currents near the equator flow toward the equator and toward the west—the same way as the trade winds. The currents between the equator and the poles tend to flow toward the east before they run into a land mass and turn around—just like the westerly winds. The currents near the poles flow to the west—just like the easterly winds.

D5.14 Ocean currents

Coriolis Effect

D5.15 Clockwise and counterclockwise currents

The Coriolis effect also affects these currents. The currents in the Northern Hemisphere are pushed in a clockwise direction, while the currents in the Southern Hemisphere are pushed in a counterclockwise direction. These factors cause some costal locations to get a continuous current of warm water, such as Victoria, British Columbia, while others get a continuous current of cold water, such as Labrador, New Foundland. This causes Victoria’s climate to be warmer than it should be when considering its location on Earth. It also causes Labrador to have a cooler climate. The location of these two cities still means that they have less variation in temperature when compared to an inland community at the same latitude, even if it is a warmer or cooler temperature, since they are near a large body of water.

  Digging Deeper

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D5.16 Water spinning as a toilet is flushed

Does water spin differently down a drain depending on what hemisphere you are in? The answer to this question has sparked much debate over the years. Some are adamant that the water does spin in different directions depending on the hemisphere; while others say that the Coriolis effect would have little to no effect and that any differences seen are due to the shape of the basin. Go to the following link to find out the answer. https://www.scientificamerican.com/article/can-somebody-finally-sett/

Learn More

  Read This

  Practice Questions

1. Complete the following chart using your readings and notes.
   
   

   Factor	Affect on Ocean Current	How It Affects Climate or Thermal Energy Transfer
   convection
   Coriolis effect
   continents
   specific heat capacity	n/a
   heat of vaporization	n/a

   
   
   Check your answer
   

   Factor	Affect on Ocean Current	How It Affects Climate or Thermal Energy Transfer
   convection	The denser cool water sinks as the less dense warm water rises, creating a current that runs from warm areas to cool areas and back.	The water absorbs thermal energy in the warm area to release it in the cooler areas.
   trade winds	These form the surface currents near the equator.	The water absorbs thermal energy and starts to move it away from the equator.
   westerlies	These form the surface currents between 30˚ and 60˚ in each hemisphere.	These bring warm water from the equator to areas farther away from the equator. They bring thermal energy to places with less thermal energy.
   easterlies	These form the surface currents at each of the poles.	These cause the cool water to start to move back toward the equator to absorb more thermal energy to bring toward the poles.
   Coriolis effect	These cause currents in the Northern Hemisphere to flow clockwise and currents in the Southern Hemisphere to flow counterclockwise.	These affect the path of thermal energy transfer; some areas will get a continuous flow of cool water, while others will get a continuous flow of warm water.
   continents	These cause currents to turn back on themselves.	These cause circular currents in some areas, which affect the path of thermal energy transfer.
   specific heat capacity	n/a	Water can absorb and release large amounts of thermal energy without affecting its own temperature and so can assist in moving thermal energy from one area to another.
   heat of vaporization	n/a	When water melts or evaporates during the hydrologic cycle, it absorbs large amount of thermal energy that can then be released when it changes back to a liquid or solid.

   
   
2. How does living near a large body of water potentially affect the climate you live in?
   
   
   Check your work.
   

   Living near a large body of water will mean there is less variation in temperature than there would otherwise be. This is because the water will release thermal energy when it is cold out and absorb thermal energy when it is warm out, keeping the temperature form reaching extremes.
   
   Depending on if you live near a warm or cool body of water, you could see a warmer climate or a cooler climate than you would otherwise see.
   

  The Biomes

©NRC
D5.17 Topography map of Canada

Topography is what the land looks like. This includes the location of mountains, large bodies of water, and large, flat spaces. These physical characteristics of the land, as well as thermal energy transfer, can have a large effect on the biomes we previously looked at. Before we look at the effects of those physical characteristics, there are two things we need to know or remember:

1. Cooler air cannot hold as much moisture as warmer air; so as air cools, the moisture in the air condenses and forms precipitation.
   
   
2. Warm air rises and cool air moves in to replace it, creating convection current, or wind.

Land and Sea Breezes

D5.18 Land and sea breezes

There are two main types of wind caused by large bodies of water. One is called a sea breeze and the other a land breeze. A sea breeze is a breeze that blows in from the large body of water. As the sun rises, the land will heat up faster than the water, since the land has a lower specific heat capacity. As the land warms, it transfers its thermal energy to the air above it, making that air warm faster than the air over the water. Since the air over the land is warmer, it rises and the cooler air from the water moves in to replace it. The warm air is pushed out over the water where it cools down and sinks. It then moves back to the land where it warms up again.

A land breeze is the opposite of a sea breeze; a land breeze blows out toward the large body of water. This occurs at night after the sun has set. The land will cool down faster than the water, again due to its specific heat capacity. As the land cools, it will take the thermal energy from the air, causing the air over the land to cool faster than the air over the water. Since the air over the water is warmer, it rises and the cool air from the land moves out over the water. It then warms up and rises. Once it rises, it is pushed back to the land where it cools and sinks back down.

These breezes help to reduce the variation in temperature of these coastal regions by evening out the thermal energy between the water and land. Remember, the temperatures can be warmer or colder than other areas depending on if the body of water is warmer or colder.

Moisture and Precipitation

D5.19 Rain in Victoria, BC

Being close to a large body of water will also increase the amount of moisture in the air, as there is more water to evaporate into the air. This can affect how cold a temperature feels. Victoria, British Columbia, has an average temperature of 4 ˚C in the winter, but it often feels much colder due to the amount of moisture in the air. On the other hand, Edmonton, Alberta, has an average temperature of –14 ˚C in the winter, but it may not seem as cold because it is much dryer.

The amount of moisture in the air also affects the amount of precipitation that is seen. As the air cools, it cannot hold onto the moisture as well and so that moisture turns into precipitation. Coastal cities such as Victoria and Vancouver, which are close to a warmer body of water, see large amounts of rain, especially in the wintertime. This is because the land is cooler than the ocean; so as the air cools over the land, the air releases the moisture it is carrying in the form of lots of rain.

On the east coast of Canada, where the ocean is cooler, the air releases the moisture as snow. Places such as New Brunswick see an average of 2 to 3 m of snow each year. Alberta sees an average of 0.7 to 2 m.

D5.20 Snow on the east coast

Effect of Mountains

But why is Edmonton so much dryer than Victoria? Alberta is not that far from the ocean, so shouldn’t we have at least a bit of the moisture that BC sees? The answer to these questions has to do with the Rocky Mountains.

As the air moves farther up the mountains, it cools down, releasing the moisture it is still carrying as precipitation. By the time the air reaches the Alberta side of the mountains, it does not contain much moisture. The air now moves down the mountains, warming up as it goes. There is very little chance to pick up more moisture, so the air remains very dry and produces very little precipitation. This is called a rain shadow. The warm, dry air that comes off the mountains is often referred to as a chinook. A great example of a region in a rain shadow is southern Alberta, including Calgary, Lethbridge, Medicine Hat, and Pincher Creek.

© By Kagee (Own work), via Wikimedia Commons
D5.21 Rain shadow or chinook

A rain shadow can occur in any place located downwind from mountains. This means that the cities are located in the direction the wind is blowing. If the wind blows to the east (such as over the Rockies, as they have westerlies blowing over them), then the cities to the east of the mountains will see a rain shadow.

  Did You Know?

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D5.22 Chinooks cause high winds

The strongest chinook in Lethbridge occurred on November 19, 1962, with gusts up to 171 km/h.

  Did You Know?

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D5.23 A month of chinooks

The areas of Pincher Creek, Crowsnest Pass, and Lethbridge see 30 to 35 chinook days per year. That is a month’s worth of chinook.

  Take Notes

  Practice Questions

1. How does a sea breeze occur?
   
   
   Check your work.
   

   A sea breeze happens as the sun rises and warms up the land faster than the sea. The warm air over the land then rises, and the cool air from the sea comes in to replace it. The warm air is pushed out over the sea where it cools and heads back toward the land. This creates a wind that blows from the sea onto the land.
   
2. How do mountains affect the climate of the cities that lay down wind of them?
   
   
   Check your work.
   

   Mountains create a dryer climate in cities that lay down wind from them.
   
3. What happens to the amount of moisture in the air as it cools?
   
   
   Check your work.
   

   The amount of moisture in the air drops as the air cools. This is because the air cannot hold onto the moisture, so it is turned into precipitation.
   
   
   

  Interactive Activity

Coastal Winds and Clouds © Explore Learning

Background Information:

This activity will help you to visualize the convection currents caused by the ocean, land breezes, and sea breezes. Remember, land and sea breezes do not just happen along the coast where land meets the ocean but also where the land meets any large body of water. This includes large lakes, such as the great lakes. Smaller bodies of water will have the same affect but to a much lesser degree. This means there will still be land and sea breezes, but they will be much less noticeable and will have a much smaller effect on the temperature of the area.

Please note: if you scroll down while in the Gizmo you will see a list of questions. You DO NOT need to complete these questions. You are able to complete them for extra practice if you would like.

• Procedure
  
• Analysis
  

1. Click on the play icon to open the Gizmo. Print students can access the Gizmo in the Online Resources for Print Students Section of their online course.
2. Click the play button and watch the simulation.
3. Click the pause button when the sailboat starts to move toward the shore. This represents the start of the sea breeze. What time is it?
   
   
   Check your work.
   

   It is around 10 a.m.
4. Click the play button and then click the pause button when the sailboat starts moving out to sea again. This represents the start of the land breeze. What time is it now?
   
   
   Check your work
   

   It is around 1 a.m.

5. Click the play button and watch the movement of the clouds. What do you notice?
   
   
   Check your work.
   

   Clouds appear early in the morning and in the afternoon. The morning clouds move toward the shore, and the afternoon clouds move toward the sea.
   

6. Click the reset button and turn on the weather probe.
7. Hypothesize about which area you think will heat up faster during the day: the land or the sea. Which will cool down faster at night?
   
   
   Check your work.
   

   You must hypothesize what you think will happen. You will use this hypothesis in your Assignment D2.
8. Click the play button on the simulation and the pause button at each of the times listed in the chart below. For each time, fill in the ocean air temperature, land air temperature, type of breeze, and wind speed by moving the weather probe to the appropriate location in the simulation.
   
   

   Time	Ocean Air Temperature (˚C)	Land Air Temperature (˚C)	Sea Breeze or Land Breeze?	Wind Speed (km/h)
   6 a.m.
   9 a.m.
   12 p.m.
   3 p.m.
   6 p.m.
   9 p.m.
   12 a.m.
   3 a.m.

9. Please return to the top of this page and click on analysis to complete the analysis questions.
   

© Explore learning
D5.24 Weather probe

1. How much does the temperature over the ocean change in one day?
   
   
   Check your work.
   

   It changes by approximately 2 ˚C.
2. How much does the temperature over the land change in one day?
   
   
   Check your work.
   

   It changes by approximately 13.5 ˚C.
   
3. At what time of day does a land breeze normally occur? What is always true when there is a land breeze?
   
   
   Check your work.
   

   The land breeze occurs when the ocean air is warmer than the land air; so it will happen at night.
   
4. How does the temperature change over the ocean and land explain the existence of land and sea breezes?
   
   
   Check your work.
   

   The sea breeze occurs when the land air is warmer than the ocean air; so it will happen during the day.
   

  Conclusion

©NASA
D5.25 Thermal energy around Earth

While the sun plays the largest role in climate creation, the way thermal energy is transferred around Earth also has a huge effect. Thermal energy is always transferred from areas of excess thermal energy to areas where there is not enough thermal energy. It can be transferred in many different ways, including global wind patterns and ocean currents. This lesson looked at each of these factors in detail and explained how each is formed.

Climates are also affected by the physical characteristics of the land. The location of large bodies of water or mountains can change the predicted climate of a location.

In the next lesson, we will look, through the use of climatographs, at some of the predicted climates and how some locations vary from those predicted climates.

  Watch This

4.4 Assignment

Unit 4 Assignment Lessons 5-6