Earth's heat budget lab answers

LAB MODULE 4: GLOBAL ENERGY

Note: Please refer to the GETTING STARTED lab module to learn tips on how to set up and maneuver through the Google Earth ( ) component of this lab.

KEY TERMS

The following is a list of important words and concepts used in this lab module:

Albedo Energy deficit Longwave radiation

Conduction Energy surplus Net radiation (net flux)

Convection Global energy budget Radiation

Constant gases Heat Radiation budget

Electromagnetic radiation Heat transfer Shortwave radiation

Electromagnetic spectrum Incoming and outgoing radiation

Solar constant

Electromagnetic waves Insolation Solar radiation

Energy Irradiance Variable gases

LAB MODULE LEARNING OBJECTIVES

After successfully completing this module, you should be able to:

● Recognize aspects of the electromagnetic spectrum ● Distinguish between shortwave and longwave radiation and its sources ● Describe the composition of the atmosphere ● Explain how heat is transferred and measured ● Define and identify patterns of global solar insolation and albedo ● Describe the flow of solar radiation ● Describe the spatial patterns of net radiation ● Provide examples of human interactions and uses with sunlight (solar

radiation)

2

INTRODUCTION

In this lab module you will examine some of the fundamental concepts and principles related to global energy. Topics include the electromagnetic spectrum, the composition of the atmosphere, solar radiation, the movement of radiation in the atmosphere, albedo and the global energy budget. While these topics may seem disparate, you will learn how they are inherently related. The module starts with four opening topics, or vignettes, which are found in the accompanying Google Earth file. These vignettes introduce basic concepts related to global energy. Some of the vignettes have animations, videos, or short articles that provide another perspective or visual explanation for the topic at hand. After reading each vignette and associated links, answer the following questions. Please note that some components of this lab may take a while to download or open, especially if you have a slow internet connection.

Expand GLOBAL ENERGY and then expand the INTRODUCTION folder.

Read Topic 1: Electromagnetic Radiation.

Question 1: Which electromagnetic waves have the most energy?

A. Radio waves B. Microwaves C. X-rays D. Gamma rays Question 2: How is Earth’s radiation budget described in the video?

A. The difference between sunlight that comes into the Earth, minus the amount of sunlight that is reflected by, and energy emitted from, the Earth

B. The difference between sunlight that is reflected by Earth, minus the energy emitted, plus the sunlight coming into the Earth

C. The difference between energy emitted by the Earth, minus the sunlight coming into the Earth, minus the sunlight reflected by the Earth

D. The difference between energy emitted by the Earth, minus the sunlight coming into the Earth, plus the sunlight reflected by the Earth

Read Topic 2: Atmospheric Composition.

Question 3: What are the three ingredients needed for an ozone hole?

3

A. Warm temperatures, sunlight, and high levels of smog B. Cold temperatures, darkness, and high levels of smog C. High level of chlorine and bromine, warm temperatures, and sunlight D. High level of chlorine and bromine, cold temperatures, and

sunlight

Read Topic 3: Transfer of Heat Energy.

Question 4: Which of the following is not true regarding the transfer of heat energy?

A. Air conducts heat effectively B. Dark-colored objects absorb more radiant energy than light-colored

objects C. Convection is the transfer of heat energy in the atmosphere D. Sunlight is a form of radiation Question 5: Of these means of transferring heat, which tend directly produce weather systems?

A. Radiation B. Conduction C. Convection D. None of these

Read Topic 4: Human Interaction.

Question 6: From the article, all of the following are recognized disadvantages of generating electricity from solar power except?

A. The amount of pollution generated B. Cost C. Daylight hours for operation D. Locations with low available sunlight Question 7: From the map in the article, what area of the United States shows the highest annual average daily solar radiation per month (measured in kWh/m2/day)?

A. Northeastern United States B. Southeastern United States C. Southwestern United States D. Northwestern United States

4

For the rest of this module, you will identify and explain the geographic distribution, patterns, and processes associated with electromagnetic radiation. In doing so, you will recognize and appreciate the role of the Sun, atmosphere and the Earth’s surface as they influence the world’s global energy budget.

Collapse and uncheck the INTRODUCTION folder.

GLOBAL PERSPECTIVE

Insolation (incoming solar radiation) is the amount of direct or diffused electromagnetic radiation the Earth receives from the Sun. Insolation can be quantified by its irradiance, which is the power – or rate of electromagnetic radiation - that strikes the surface of a given area. As power is measured in Watts (W), and area is measured in meters squared (m2), irradiance is commonly measured in Watts per meter squared (W/m2).

The Sun produces a fairly constant rate of solar radiation at the outer surface of the Earth’s atmosphere; this solar constant averages to approximately 1370 W/m2. However, the average amount of solar radiation received at any one location on the Earth is not ~1370 W/m2 – it is far less, due in part to the conditions of the atmosphere, the land cover, the given latitude, the time of day, and the time of year.

Expand the GLOBAL PERSPECTIVE folder and select Insolation in June. To close the citation, click the X in the top right corner of the window.

This map shows the average global solar insolation – or where and how much sunlight fell on the Earth’s surface - for the month of June in 2012. The legend in the top left corner shows how much sunlight fell on Earth’s surface, which ranges from a low of 0 W/m2 (purple/dark red) to a high of 550 W/m2 (white). Use this map layer to answer the following questions.

Double-click and select Location A.

Question 8: What is the approximate latitude of Location A (Oslo, Norway)?

A. 60N B. 60S C. 10E D. 10W

5

Question 9: Estimate the average solar insolation Location A (Oslo, Norway) received in June:

A. Near 0 W/m2 B. Near 275 W/m2 C. Near 400 W/m2 D. Near 550 W/m2

Double-click and select Location B.

Question 10: What is the latitude of Location B (Isla de los Estados, Argentina)?

A. 54N B. 54S C. 64E D. 64W Question 11: Estimate the average solar insolation Location B (Isla de los Estados, Argentina) received in June:

A. Near 0 W/m2 B. Near 275 W/m2 C. Near 400 W/m2 D. Near 550 W/m2 Question 12: Which location received greater average solar insolation in June – Location A or Location B? Explain why.

A. Location B, because it is closer to the equator B. Location A because it receives more daylight hours in June C. Location B because it’s a darker orange color D. Location A because it’s farther from the subsolar point in June

Double-click and select Insolation in December. To close the citation, click the X in the top right corner of the window

This map shows the average global solar insolation received in December. The legend in the upper right corner shows how much sunlight fell on Earth’s surface, which ranges from a low of 0 W/m2 (dark red) to a high of 550 W/m2 (light yellow). Use this map layer and compare it to Insolation in June to answer the following questions.

Double-click Location A.

6

Question 13: Estimate the average solar insolation Location A (Oslo, Norway) received in December:

A. Near 0 W/m2 B. Near 275 W/m2 C. Near 400 W/m2 D. Near 550 W/m2 Question 14: Which of the following explains the difference in average solar insolation at Location A (Oslo, Norway) in June and December? (Check all that apply).

A. Location A is further from subsolar point in December B. Location A receives more daylight hours in December C. Location A is close to the Equator (low latitude) D. Location A is closer to the subsolar point in June

Double-click Location B.

Question 15: Estimate the average solar insolation Location B (Isla de los Estados, Argentina) received in December:

A. Near 0 W/m2 B. Near 275 W/m2 C. Near 400 W/m2 D. Near 550 W/m2 Question 16: Which of the following explains the difference in average solar insolation at Location B (Isla de los Estados, Argentina) in June and December? (Check all that apply).

A. Location B is further from subsolar point in December B. Location B receives more daylight hours in December C. Location B is far from the Equator (high latitude) D. Location B is closer to the subsolar point in June Question 17: What is the general trend of solar insolation at Location A compared to Location B in June and December?

A. Location A and B show the same trend, with insolation high in June and low in December

B. Location A and B show the same trend, with insolation high in December and low in June

C. Location A and B show opposite trends, with insolation high at one location and low at the other location

D. Location A and B show no trend in December or in June

7

Uncheck Location A and Location B. Double-click and select Location C.

Question 18: What is the latitude of Location C (Yasuni National Park, Ecuador)?

A. 1N B. 1S C. 75W D. 75E Question 19: Estimate the average solar insolation that Location C (Yasuni National Park, Ecuador) received in June:

A. Near 0 W/m2 B. Near 275 W/m2 C. Near 400 W/m2 D. Near 550 W/m2 Question 20: Estimate the amount of solar insolation Location C (Yasuni National Park, Ecuador) received in December:

A. Near 0 W/m2 B. Near 275 W/m2 C. Near 400 W/m2 D. Near 550 W/m2 Question 21: Which of the following accounts for the trends in average solar insolation at Location C (Yasuni National Park, Ecuador) in June and December? (Check all that apply).

A. There is relatively minor differences in sun angle B. There is relatively minor differences in daylight hours C. Location C is close to the Equator (low latitude) D. Location C is far from subsolar point in December Question 22: Which of the following is true about how latitude and calendar date affect where and how much sunlight falls on the Earth’s surface in a given year? (Check all that apply).

A. The higher the latitude the greater the seasonal difference in daylight hours

B. Higher southern latitudes receive more daylight hours around the June solstice.

C. Higher northern latitudes receive more daylight hours around the June solstice.

8

D. The lower the latitude the greater the seasonal difference in daylight hours

Collapse and uncheck GLOBAL PERSPECTIVE.

FLOW OF SOLAR RADIATION

When energy from the Sun reaches the Earth’s atmosphere, it flows along various paths, with some energy absorbed by the atmosphere, some reflected back into space and some striking the Earth’s surface. These various paths are part of the heat transfer mechanism that distributes heat across the globe. A more detailed breakdown of what happens is shown in the solar radiation animation. To note, the values shown in the animation are for the Earth as a whole.

Select and click FLOW OF SOLAR RADIATION.

Question 23: What percent of the Sun’s energy entering the Earth’s atmosphere is absorbed directly by the atmosphere?

A. 18% B. 25% C. 31% D. 69% Question 24: What percent of the Sun’s energy (shortwave radiation) entering the Earth’s atmosphere is absorbed by Earth is some way (clouds, water, Earth’s surface)?

A. 18% B. 25% C. 31% D. 69% Question 25: What accounts for the most solar radiation being reflected back into space?

A. Dust particles B. Ozone C. Clouds D. Aerosols Question 26: Why does incoming shortwave radiation equal outgoing longwave radiation? (Check all that apply).

A. To keep the Earth’s average temperature more or less constant

9

B. The laws of physics require incoming and outgoing radiation to equal C. It maintains the thickness of the atmosphere and variability in the length

of day D. Without a balanced radiation budget, the Earth will become increasingly

warmer or cooler Question 27: The values in the animation are for the Earth as a whole, however, the flow of energy is not even across the Earth’s surface. Speculate how net radiation differs at the Equator compared to the Poles. (Check all that apply).

A. Net radiation is more or less constant near the Equator, but varies at the Poles

B. Net radiation is more or less constant near the Poles, but varies at the Equator

C. During the June Solstice, net radiation is greater at the North Pole than the Equator

D. During the December Solstice, net radiation is greater at the North Pole than the Equator

Uncheck the FLOW OF SOLAR RADIATION folder.

ALBEDO

Expand the ALBEDO folder. Double-click and select Albedo in September. To close the citation, click the X in the top right corner of the window.

Albedo is the portion of solar energy (shortwave radiation) that is reflected from Earth’s surface back into space. Albedo is calculated as the relative amount (ratio) of reflected sunlight (reflected shortwave radiation) to the total amount of sunlight (incident shortwave radiation). Clouds and bright (light-colored) surfaces have higher albedo rates than dark colored surfaces like asphalt, roads and forests.

This map shows the average global albedo received in September. The legend at the top shows the proportion of sunlight reflected from Earth’s surface, which ranges from no albedo at 0.0 (dark blue) to a high albedo at 0.9 (light blues to white). Areas of no data are denoted as black or no color. Use this map layer to answer the following questions.

Double-click and select Location D; then, double-click and select Location E.

10

Question 28 Is the albedo relatively high or relatively low in the boreal forests of Canada and Norway in September?

A. The albedo is relatively high in both locations B. The albedo is relatively low in both locations C. The albedo is high in northern Canada and low in Norway D. The albedo is low in northern Canada and high in Norway

Double-click and select Location F.

Question 29: Is the albedo relatively high or relatively low in the Sahara Desert region of Northern Africa in September?

A. The albedo over the Sahara Desert is relatively low B. The albedo over the Sahara Desert is relatively high C. There is no albedo over the Sahara Desert because sand does not reflect

sunlight D. The albedo over the Sahara Desert is only very high (near 0.9) or very

low (0.0)

Double-click and select Location G.

Question 30: Is the albedo relatively high or relatively low over the majority of Greenland in September?

A. The albedo over Greenland is relatively low except near the coast B. The albedo over Greenland is relatively high except near the coast C. There is no albedo over Greenland except near the coast D. There is no albedo over Greenland because ice and snow do not reflect

sunlight Seasonality (time of the year) plays an important role in global albedo. Let’s compare the September albedo rates to February albedo rates of these locations.

Select and double-click Albedo in February. To close the citation, click the X in the top right corner of the window. To alternate between Albedo in September and Albedo in February, check and uncheck one of the files to see the differences in the two map overlays.

Double-click Location D; then, double-click Location E.

Question 31: For northern Canada and Norway, is the albedo in February higher or lower when compared to the albedo in September?

A. The albedo is higher in February for both locations

11

B. The albedo is lower in February for both locations C. The albedo is higher in northern Canada and lower in Norway D. The albedo is lower in northern Canada and higher in Norway

Double-click Location F.

Question 32: For the Sahara Desert region of Northern Africa, is the albedo higher or lower in February when compared to the albedo in September?

A. The albedo is lower in February B. The albedo is higher in February C. The albedo is relatively the same in February and September D. There is no albedo over the Sahara Desert because sand does not reflect

sunlight

Double-click Location G.

Question 33: For Greenland, is the albedo higher or lower in February when compared to the albedo in September?

A. The albedo is lower in February B. The albedo is higher in February C. The albedo is relatively the same in February and September D. There is no albedo over Greenland because ice and snow do not reflect

sunlight

Collapse and uncheck the ALBEDO folder.

NET RADIATION

Net radiation, sometimes called net flux, is the difference between incoming solar radiation absorbed by the Earth’s surface and the radiation reflected back into space. In other words, net radiation is the energy available to Earth at the Earth’s surface. Some places absorb more energy than reflect, while other places on Earth reflect more energy than absorb. Factors that affect the net radiation of a place include albedo, latitude and Sun angle, atmospheric conditions (like clouds and dust), and the time of year. As a result, some areas will have a seasonal or annual energy surplus with a positive net radiation (more energy absorbed than reflected) while other areas will have a seasonal or annual energy deficit with a negative net radiation (more energy reflected than absorbed). Fortunately, the Earth has a global energy budget at approximately equilibrium, with a global net radiation at approximately zero (that is, global incoming energy equals global outgoing energy).

12

Expand the NET RADIATION folder.

Double-click and select Net Radiation in January.

The legend at the top shows the global net radiation for January, which ranges from 280 W/m2 to -280 W/m2. Hence, an orange or red color indicates a greater (positive) net radiation, while a green or blue color indicates a lower (negative) net radiation.

Question 34: What global spatial patterns are apparent? (Check all that apply).

A. Net radiation is higher in the Southern Hemisphere B. Net radiation is higher in the Northern Hemisphere C. Net radiation is lower in the Southern Hemisphere D. Net radiation is lower in the Northern Hemisphere Question 35: How does the net radiation of oceans versus land differ in Northern Hemisphere compared the Southern Hemisphere in January? (Check all that apply).

A. The net radiation is relatively higher in the oceans than on land in the Northern Hemisphere

B. The net radiation is relatively lower in the oceans than on land in the Northern Hemisphere

C. The net radiation is relatively higher in the oceans than on land in the Southern Hemisphere

D. The net radiation is relatively lower in the oceans than on land in the Southern Hemisphere

Question 36: What factors contribute to the North Pole region having the highest net radiation loss in January? (Check all that apply).

A. The Sun angle is low and therefore the incoming solar radiation is low B. The Sun angle is high and therefore outgoing solar radiation is high C. The daylight hours are few indicating less incoming solar radiation D. The daylight hours are few indicating less outgoing solar radiation

Double-click and select Net Radiation in July.

Question 37: What global spatial patterns are apparent? Check all that apply.

A. Net radiation is higher in the Southern Hemisphere B. Net radiation is higher in the Northern Hemisphere

13

C. Net radiation is lower in the Southern Hemisphere D. Net radiation is lower in the Northern Hemisphere Question 38: In general, how does the July map compare to the January map? (Check all that apply).

A. Overall, net radiation in the high latitudes is relatively high (energy surplus) where it was once low (energy deficit) and vice versa

B. Overall, there is an energy surplus at the Equator for both January and July

C. Overall, there is an energy surplus in the Northern Hemisphere in July D. Overall, there is an energy deficit in the Northern Hemisphere in July Question 39: What factors are contributing to Greenland showing a net radiation loss in July?

A. Because it is further north and receives less incoming solar radiation B. Because it is surrounded by warmer ocean water C. Because it is largely covered in ice and therefore has a high albedo D. Because there is a low Sun angle that contributes to a low albedo

Collapse and uncheck the NET RADIATION folder. You have completed Lab Module 4.