LAB MODULE 5: GLOBAL TEMPERATURE PATTERNS

Transcription

1 LAB MODULE 5: GLOBAL TEMPERATURE PATTERNS Note: Please refer to the GETTING STARTED lab module to learn how to maneuver through and answer the lab questions using the Google Earth ( KEY TERMS You should know and understand the following terms: ) component. Air temperature Heat index Temperature anomalies Altitude Kelvin (K) Temperature averages Ambient temperature Latitude Thermopause Axial Tilt Maritime effect Thermosphere Celsius (C) Mesopause Tropopause Continentality, or Mesosphere Troposphere Continental effect Stratopause Urban heat island Environmental Lapse Rate Stratosphere Urban heat island effect Exosphere Structure of the atmosphere Wind chill Fahrenheit (F) Surface temperature LAB MODULE LEARNING OBJECTIVES After successfully completing this module, you should be able to the following tasks: Describe the differences between air and surface temperature Explain heat index and wind chill Explain the urban heat island effect Describe the structure of the atmosphere Describe large scale factors influencing temperature Describe local factors influencing temperature 1

2 INTRODUCTION This lab module explores the global surface and air temperatures of Earth and Earth s atmosphere. Topics include the structure of the atmosphere, local and global factors influencing temperature, and temperature anomalies. The modules start with four opening topics, or vignettes, which are found in the accompanying Google Earth file. These vignettes introduce basic concepts of the internal structure of the Earth. Some of the vignettes have animations, videos, or short articles that will provide another perspective or visual explanation for the topic at hand. After reading the vignette and associated links, answer the following questions. Please note that some links might take a while to download based on your Internet speed. Expand the INTRODUCTION folder. Read Topic 1: Surface and Air Temperature Question 1: How do the surface temperatures of the countries in the northern latitudes (for example, Canada, Iceland, Norway, and Russia) compare to those of northern Africa (for example, Algeria, Egypt, Libya, Morocco, and Sudan)? A. The temperatures are higher in the northern latitudes during summer months when net radiation is higher. B. The temperatures are lower in north Africa during the summer months when net radiation is higher in northern latitudes. C. Temperatures are lower in northern latitudes year-round. D. Temperatures are only lower in the northern latitudes during winter months. Read Topic 2: Measuring Temperature Question 2: Considering water freezes (or alternatively, melts) at 0 C, determine from the map which countries or landmasses have an annual mean temperature around 0 C. A. Canada and Norway B. The United States and the United Kingdom C. Greenland and Antarctica D. Russia and Antarctica 2

3 Read Topic 3: Heat Index and Wind Chill Question 3: The heat index on a warm day (86 F or 30 C) when the relative humidity is 50% is: A. 87F B. 90F C. 31C D. 33F Read Topic 4: Human Interaction Question 4: Identify three negative impacts of heat islands. A. Increased energy consumption, elevated greenhouse gases, improved water quality B. Compromised human health, lower energy consumption, lower water quality C. Decreased greenhouse gases, higher energy consumption, compromised human health D. Increased greenhouse gases, greater air pollution, increased energy consumption Collapse and uncheck the INTRODUCTION folder. 3

4 GLOBAL PERSPECTIVE Perhaps you recall news reports on extreme temperature-related weather patterns, such as the colder-than-normal winter in the western USA, or the 2003 European summer heat wave (which led to more than 35,000 deaths). These examples are temperature anomalies, as they deviate significantly from temperature averages that are based on decadal (or longer) year records. Temporary temperature anomalies are usually due to non-permanent weather phenomena like a passing storm or seasonal drought; however, more permanent temperature anomalies could signify the presence of urban heat islands, and if widespread, global climate change. Temperature anomalies can have significant impacts on farming and ranching, recreation, and even human health. Expand the GLOBAL PERSPECTIVE folder and then check Temperature Anomalies in January. To close the citation, click the X in the top right corner of the window. This imagery uses the following color scheme to show land surface temperature anomalies during the month of January 2011 as compared to average conditions for the month in 2000 to 2008: Red - warmer-than-average temperatures Blue - cooler-than-average temperatures Black - no data Temperatures ranged from 12 C below to 12 C above the normal January temperature. Verify that Borders and Labels and Places are checked in the Layers panel. To note, you might have to zoom in or out for the location name to appear. Double-click and select Location A. Question 5: What is the name of this US county? (You might have to zoom in to see place names.) A. Lasalle B. Bureau C. Putnam D. Marshall Question 6: Is the temperature anomaly warmer or colder? A. The anomaly is warmer 4

5 B. The anomaly is colder C. There is no anomaly, temperature is the same D. Unable to discern Double-click and select Location B. Question 7: What is the name of the European city? A. Ludres B. Frouard C. Nancy D. Toul Question 8: Is the temperature anomaly warmer or colder? A. The anomaly is warmer B. The anomaly is colder C. There is no anomaly, temperature is the same D. Unable to discern Double-click and select Location C. Question 9: What is the name of the capital city? A. Windhoek B. Okahandja C. Pretoria D. Khomas Question 10: Is the temperature anomaly warmer or colder? A. The anomaly is warmer B. The anomaly is colder C. There is no anomaly, temperature is the same D. Unable to discern Uncheck Temperature Anomalies in January. Double-click and select Temperature Anomalies in August. To close the citation, click the X in the top right corner of the window. This imagery shows land surface temperature anomalies during the month of August

6 Return to Location B. Question 11: What is the temperature anomaly (in C)? A. -12 C B. -4 C C. 4 C D. 10 C Question 12: How does this anomaly compare to the one in January 2011? A. The anomaly is warmer B. The anomaly is colder C. There is no anomaly, temperature is the same D. Unable to discern Collapse and uncheck the GLOBAL PERSPECTIVE folder. STRUCTURE OF THE ATMOSPHERE The structure of the atmosphere impacts temperature. To begin, Earth s atmosphere is not uniform, but is comprised of layers. The layer closest to the surface is called the troposphere. Because the troposphere s temperature is based on long wave radiation emitted from the Earth s surface, temperature decreases with elevation in this layer of the atmosphere. This change in temperature with altitude is called the environmental lapse rate. Click STRUCTURE OF THE ATMOSPHERE. Watch the animation and answer the following questions: Question 13: Why does the temperature increase in the upper portion of the stratosphere? A. Because long wave radiation is heating the earth s surface B. Because ozone blocks ultra-violet radiation and releases heat C. Because clouds are able to trap heat D. Because heat is trapped in this portion of the atmosphere Question 14: Because temperature increases as altitude increases in the stratosphere, is the environmental lapse rate positive or negative? A. The lapse rate is positive 6

7 B. The lapse rate is negative C. The lapse rate is zero D. Unable to discern Question 15: Why are temperatures in the thermosphere so high? A. Because this layer is closest to the sun B. Because of intense solar radiation C. Because there are so few molecules D. Because of the lack of pollutants Question 16: Would it feel hotter on a warm summer day in the thermosphere or the troposphere? (Hint: Think composition!) A. In the thermosphere because temperature reaches over 1000F B. In the troposphere because temperature reaches over 1000F C. In the thermosphere because of the intense solar radiation D. In the troposphere because there are more air molecules to retain heat The environmental lapse rate can be used to determine a given temperature of a location, provided that the lapse rate and altitude are known. The standard environmental lapse rate as you go up in altitude is 6.4 C/1000m. In other words, as you go up 1000 meters, the temperature decreases 6.4 C For the following questions, however, assume a negative environmental lapse rate of 6.4 C/1000m. So how do you solve this? Here is an example: You have a location Town M. Town M that has an altitude of 100m and its air temperature is 10 C. At 1000m the air temperature is different but what is it? How do we figure out the temperature at 1000m? To solve: First, make sure you know the initial temperature and distance between the start location and the end location. Initial temperature: 10 C Distance: 1000m 100m = 900m Next, let s set up the equation: Environmental lapse rate = x/distance 7

8 Where x is the unknown air temperature for Town M. Plug in the numbers and units: 6.4 C/1000m = x/900m Now we multiply 900m on both sides. 6.4 C*900m/1000m = x/900m * 900m 6.4 C*900m/1000m = x The m/m means that the meters cancel out, leaving only C as a unit. If we do the math, our answer is as follows: x = 6.4 C*900m/1000m x = 5.76 C This value means your change in temperature was 5.76 C. Now, take the initial temperature value (10 C) and subtract the calculated x temp (5.76 C) from it. 10 C C = 4.24 C Note that this is a negative environmental lapse rate meaning you subtract going up in elevation, and add going down in elevation. Question 17: The altitude in town N is 1000m and the air temperature is 22 C. What is the air temperature (in C) at 3000m? A. 22 C - (3000m-1000m)*6.4/1000m = 9.2 C B. 22 C + (3000m-1000m)*6.4/1000m = 34.8 C C. 22 C - (3000m-1000m)*5.76/1000m = 10.5 C D. 22 C - (3000m-1000m)*5.76/1000m = 33.5 C Question 18: The altitude in town P is 1000m and the air temperature is 18 C. What would be the temperature (in C) of Town P if it were located instead at 500m? A. 18 (1000m-500m) *6.4/1000m = 21.2 C B (1000m-500m) *6.4/1000m = 14.8 C C (1000m+500m) *6.4/1000m = 27.6 C D (1000m+500m) *6.4/1000m = 9.0 C Uncheck the STRUCTURE OF THE ATMOSPHERE folder. 8

9 FACTORS INFLUENCE AIR TEMPERATURE Global Scale Factors There are several global-scale factors that influence air temperature. These include latitude, axial tilt (and length of day), and time of day. Latitude Latitude affects net radiation (energy). Locations in lower latitudes (for example, near the Equator) have net gain (or surplus) of radiation, while higher latitudes (for example, near the North or South Pole) have a net loss (or deficit) of radiation. Where there is a surplus of energy, there are higher air temperatures. Thus, tropical and sub-tropical regions have a higher annual average air temperature than polar and sub-polar regions. Axial Tilt The tilt of the Earth s axis is one of the major reasons the Earth has seasons. The location where the most energy from the Sun (as sunlight) directly hits the Earth s surface is called the subsolar point. In the Northern Hemisphere in June, the subsolar point is at or near the Tropic of Cancer (23.5 degrees North of the Equator) and the days are longer. In contrast, the subsolar point is furthest from the Northern Hemisphere in December (23.5 degrees South of the Equator) and the days are shorter. As a result, the air temperature in the Northern Hemisphere is higher in June (thereby summer) and lowers in December (thereby winter). Time of day Lastly, the time of day affects air temperature. Usually, the temperature is warmer during the day and cooler at night. Local noon time is the peak of solar radiation. However, there is a temperature lag, and the peak air temperature is usually a few hours after the peak of solar radiation. This is because the sunlight reaching the Earth s surface needs time to heat it up, and then re-radiate the energy back into the atmosphere as long wave (thermal) radiation. Expand the AIR TEMPERATURE folder and then expand the Global-Scale Factors folder. Select Day Temperatures in December. To close the citation, click the X in the top right corner of the window. Double-click and select Location D. 9

10 Question 19: Estimate the average monthly daytime temperature in December for this location. A. 0 C B. 5 C C. 15 C D. 25 C Question 20: Record the latitude for this location. A. 58N B. 58S C. 34N D. 34S Double-click and select Location E. Question 21: Estimate the average monthly daytime temperature in December for this location. A. 0 C B. 5 C C. 10 C D. 25 C Question 22: Record the latitude for this location. A. 33S B. 33N C. 84N D. 84S Question 23: What global-scale factor(s) accounts for the temperature difference between Locations D and E? Check all that apply. A. Latitude B. Axial tilt C. Time of day D. All of the above Click Night Temperatures in December. To close the citation, click the X in the top right corner of the window. Double-click and select Location F. 10

11 Question 24: Estimate the average monthly night time December temperature for location F. A. -20 C B. 0 C C. 5 C D. 15 C Double-click and select Location G. Question 25: Estimate the average monthly night time December temperature for location G. A. -15 C B. 0 C C. 5 C D. 10 C Question 26: Account for the temperature difference you recorded for Location F and G. A. Latitude B. Axial tilt C. Time of day D. All of the above Question 27: What global-scale factor(s) accounts for the temperature difference you recorded between Locations E and F? A. Latitude B. Axial tilt C. Time of day D. All of the above Collapse and uncheck the Global-Scale Factors folder. Local Scale Factors In addition to large-scale factors influencing temperature, there are also three notable local-scale factors; namely, proximity to a large body of water (maritime effect versus continentality), altitude, and the urban heat island effect. 11

12 Maritime versus Continental The maritime/continental factor refers to the proximity to a large body of water. If a location is located near the ocean (like Seattle, Washington, USA), its temperature is influenced by a maritime effect. This means that average temperatures are moderated, and are not significantly higher than the average in the summer or Figure 1. Average monthly temperatures for Seattle and Lincoln. significantly lower than the average in the winter months. Conversely, locations experiencing a continental effect on their temperatures (like Lincoln, Nebraska, USA) have colder temperatures in the winter and warmer temperatures in the summer months. Figure X illustrates the maritime/continental effect on temperature. In the winter months, Seattle, Washington is up to 16F warmer than Lincoln, but in the summer months, Lincoln is 14F warmer than Seattle. Altitude Altitude is the second local factor affecting temperature. In general, locations at a lower altitude have a warmer temperature than those at a higher altitude. The temperatures of both Denver, Colorado and Kansas City, Missouri are located roughly at latitude of 39 N, and are Figure 2. Average monthly temperatures for Denver and Kansas City. influenced by the continental effect. However, Denver is located at approximately 5,280 feet, while Kansas City is located at approximately 973 feet in elevation. Figure 2 shows that on average, temperatures are warmer in Kansas City, MO than in Denver, CO, owing in large part to a difference in altitude. 12

13 Urban Heat Island An urban heat island is a phenomenon in which urban areas are generally warmer than the surrounding rural areas. This is due to the amount of impervious surfaces such as roads, buildings and parking lots found in urban centers. These surfaces, plentiful within Figure 3. Average monthly temperatures for Atlanta and Acworth. most urban areas, tend to emit more long wave radiation (heat energy) than do rural areas dominated by natural vegetation, crops or soil. Figure 3 illustrates the urban heat island effect. Atlanta is a major city in the US, while Acworth is a small city located northwest of downtown Atlanta. The graph shows that temperatures are slightly warmer in urban Atlanta, compared to suburban Acworth. Before you begin this section, make sure that you have Borders and Labels selected under the Layers panel in Google Earth. Expand the Local Scale Factors folder. Check Average Temperature in July. Double-click and select Location H. Question 28: Estimate the average monthly July temperature for Location H. A. 0 C B. 5 C C. 15 C D. 25 C Double-click and select Location I. Question 29: Estimate the average monthly July temperature for Location I. A. 0 C 13

14 B. 5 C C. 15 C D. 25 C Question 30: What of these local-scale factors continental versus maritime effect, altitude, or urban heat island effect - is most influencing the difference in temperature between Locations H and I? A. Maritime effect B. Altitude C. Urban heat island D. None of the above Double-click and select Location J. Question 31: Estimate the average monthly July temperature for Location J. A. 0 C B. 5 C C. 15 C D. 30 C Double-click and select Location K. Question 32: Estimate the average monthly July temperature for Location K. A. 0 C B. 5 C C. 15 C D. 25 C Question 33: What of these local-scale factors continental versus maritime effect, altitude, or urban heat island effect - is most influencing the difference in temperature between Locations J and K? A. Maritime effect B. Altitude C. Urban heat island D. None of the above 14

15 Double-click and select Location L. Question 34: Estimate the average monthly July temperature for Location L. A. 0 C B. 5 C C. 15 C D. 20 C Double-click and select Location M. Question 35: Estimate the average monthly July temperature for Location M. A. 0 C B. 5 C C. 15 C D. 20 C Question 36: What of these local-scale factors continental versus maritime effect, altitude, or urban heat island effect - is most influencing the difference in temperature between Locations L and M? A. Maritime effect B. Altitude C. Urban heat island D. None of the above Question 37: What of these local-scale factors continental versus maritime effect, altitude, or urban heat island effect would most likely show same trend in average monthly temperature in January as in July? (Hint: Figures 1-3) A. Maritime effect B. Altitude C. Urban heat island D. None of the above 15

16 Question 38: What of these local-scale factors continental versus maritime effect, altitude, or urban heat island effect would likely show an opposite trend in average monthly temperature in January as in July? (Hint: Figures 1-3) A. Maritime effect B. Altitude C. Urban heat island D. None of the above Collapse and uncheck the Local-Scale Factors folder. You have completed Lab Module 5. 16