Exercise 5: Microclimates (LAB)

Name_______________________ Exercise 5, Introduction GPH 113 INTRODUCTION TO PHYSICAL GEOGRAPHY LABORATORY MICROCLIMATES • • • • • TARGET SKILLS Define microclimates and be able to explain why they vary Identify features of an environment and predict the way in which they affect local microclimate Use meteorological instruments to gather microclimatic data Analyze data and use it to create a detailed description of a given microclimate Observe a microclimate and identify key features that are controlling its temperature and humidity TOOLS YOU’LL BE USING Sling psychrometer Soil thermometer/probe Infrared thermometer Clipboard KEY TERMS PART 1: Microclimate Albedo Wind chill Heat index 1 Author: Dr. J. Johnson 2005 Anemometer Name_______________________ Exercise 7, Part 2 EXERCISE 5, PART 1: FACTORS OF MICROCLIMATES MICROCLIMATES In prior lab exercises, the weather systems you have studied were very large, affecting areas ranging from a few square miles to thousands of square miles, and extending to great heights in the atmosphere. Now we will shift our focus to much smaller areas, and limit our study to the first few meters of air above the surface, where temperature and humidity can vary drastically within a few centimeters. Undoubtedly you have noticed that there is drastic difference between walking across an asphalt parking lot in July and sitting under a shady tree on cool grass. Without realizing it, you were noticing the effects of microclimate. There are many factors that can influence the temperature and humidity at a given location and ultimately create the microclimate experienced there. By considering all that you have learned about the Earth and Sun so far, you can make a very useful evaluation of the factors that influence variations in temperature and humidity. We’ll expand on some of your knowledge here and discuss how it relates to microclimate. 1) Solar radiation: We know that the angle and intensity of solar radiation affects temperature, with higher temperatures resulting from more intense radiation receipt. When considering the microclimate of an area, ask yourself these questions. a. What is the orientation and slope? Does it face south and get more direct rays, or does it face north where it is shaded from the sun in the southerly sky? b. How much shade does the location receive? Is it fully lit all day? Does it receive only weak morning sun, or only stronger afternoon sun? c. What is the weather like at the time of your observations? Is it cloudy or clear? How does this influence your data? d. Is there anything present that traps shortwave or longwave energy near the surface? 2) Albedo: The albedo of a surface determines how much solar radiation is reflected and how much is absorbed. A surface with a high albedo will reflect large portions of shortwave radiation, and thus remain cooler. A surface with a low albedo will absorb large portions of shortwave radiation, and its temperature will rise accordingly. When evaluating microclimate, consider these questions. a. What color is the surface? What does this imply about the albedo of that surface? b. How will the albedo affect the temperature of the surface? How will the surface temperature in turn affect the air temperature? 2 Author: Dr. J. Johnson 2005 Name_______________________ Exercise 5, Part 1 3) Water and Vegetation: The presence of water and/or vegetation can have a dramatic impact on the microclimate of a location. Water at the surface is available for evaporation, which cools the air in two ways. First, energy from solar radiation is always used first to evaporate available water, and any remaining energy will be used to warm the air. (If there is no water to evaporate, all of the energy will be used to heat the air.) Second, evaporation is a cooling process that removes heat energy from the air. Vegetation can also provide a cooling effect in a microclimate. It is often irrigated, it provides shade, and it often has a higher albedo than the bare ground. When evaluating a microclimate, consider these questions. a. How much vegetation is growing, and what type of vegetation is it? Does it provide shade or alter the albedo of the surface? b. How much water is present? Is it a temporary supply (such as a rain puddle) or a permanent supply (such as a pond or irrigation system)? c. How recently has it rained? Is the surface wet or dry? d. What is the dew point of the air? Is the air dry, encouraging evaporation, or is it fairly moist, discouraging evaporation? 4) Wind: By moving warmed air molecules away from a hot surface, wind can keep air temperatures considerably cooler than might occur if the air sat stagnantly over the surface and continued to warm. Wind can also sweep away humidity and bring in drier air that allows evaporation to occur more easily. Wind can also influence your perception of temperature by enhancing your skin’s ability to evaporate sweat, so that you feel cooler. In the winter, this effect leads to wind chill – your body’s perception of a colder temperature than the thermometer reads. In the summer, the presence of high humidity causes your sweat to evaporate less easily, so that you perceive the air to be warmer than it is. This phenomenon is measured with the heat index. When observing a microclimate, consider these factors related to wind. a. What is the current wind speed? How does it affect your perception of the microclimate? b. Is the wind being channeled (such as through a narrow passage between buildings) and blowing faster than usual? Is the microclimate entirely sheltered from wind? c. How does the wind you’ve observed affect the microclimate in terms of temperature, evaporation, and humidity? 5) Anthropogenic Considerations: People frequently attempt to alter microclimate to increase comfort. Consider these questions during your research. a. If you are outdoors, how have people altered the microclimate? Are there misters, umbrellas, or something else? How successful at making the microclimate more comfortable do you judge these attempts to be? b. If you are indoors, the entire microclimate is created. How is this accomplished? Air conditioning or heating? Light colored shingles on the roof? Ceiling fans? What else? 3 Author: Dr. J. Johnson 2005 Name________________ Exercise 5, Part 1 PRACTICE Today you will take meteorological instruments out on campus on a microclimate scavenger hunt. The purpose of this exercise is to get you thinking about factors that influence microclimate and to familiarize you with the instruments. Make sure that everyone in your group takes turns with the instruments. This exercise will be a contest among the groups, so take some time to think it through! RULES OF ENGAGEMENT NATURAL FEATURES: Your goal is to collect the following information from any location on campus where you think it might occur. You may go inside or outside. You may NOT use any artificially created extreme conditions. (In other words, do not blow on the anemometer, do not point the IRT at a freezer/running car engine/cigarette lighter, etc.) If you wish for your entry to count, you must give a detailed description of exactly where your data were collected. For surface temperatures, you are required to take three measurements and average them. OBJECTIVE: Be the group to measure the highest/lowest/most representative data in each category. You MUST describe the location and the factors that caused that microclimate to exist in that place. 1. Highest surface temperature WHERE AND WHY: #1____________ #2____________ #3____________ AVERAGE:____________ 2. Lowest surface temperature WHERE AND WHY: #1____________ #2____________ #3____________ AVERAGE:____________ 3. Greatest wet bulb depression WHERE AND WHY: Dry Bulb:_____________ Wet Bulb: _____________ Depression:____________ 4 Name________________ Exercise 5, Part 1 4. Lowest wet bulb depression WHERE AND WHY: Dry Bulb:___________ Wet Bulb: _____________ Depression:_____________ 5. Highest soil probe temperature WHERE AND WHY: Soil temperature:________________ 6. Lowest soil probe temperature WHERE AND WHY: Soil temperature:________________ 7. Greatest wind speed WHERE AND WHY: Wind speed:________________ RULES OF ENGAGEMENT PART II MAN-MADE FEATURES: Your goal is to collect the following information from any location on campus where you think it might occur. You may go inside or outside. You may now use any artificially created extreme conditions. (In other words, blow on the anemometer, point the IRT at a freezer/running car engine/cigarette lighter, etc.) If you wish for your entry to count, you must give a detailed description of exactly where your data were collected. For surface temperatures, you are required to take three measurements and average them. 5 Name________________ Exercise 5, Part 1 OBJECTIVE: Be the group to measure the highest/lowest/most representative data in each category. You MUST describe the location and the factors that caused that microclimate to exist in that place. 8. Highest surface temperature WHERE AND WHY: #1____________ #2____________ #3____________ AVERAGE:____________ 9. Lowest surface temperature WHERE AND WHY: #1____________ #2____________ #3____________ AVERAGE:____________ 10. Greatest wet bulb depression WHERE AND WHY: Dry Bulb:_____________ Wet Bulb: _____________ Depression:____________ 11. Lowest wet bulb depression WHERE AND WHY: Dry Bulb:___________ Wet Bulb: _____________ Depression:_____________ 12. Highest soil probe temperature WHERE AND WHY: Soil temperature:________________ 6 Name________________ Exercise 5, Part 1 13. Lowest soil probe temperature WHERE AND WHY: Soil temperature:________________ 14. Greatest wind speed WHERE AND WHY: Wind speed:________________ WRAP UP: Place a star by any contest your group won. How do you think your measurements were influenced by current or recent weather? 7 Name_______________________ Exercise 5, Part 2 EXERCISE 5, PART 2: EVALUATING CAMPUS MICROCLIMATES In order to receive full credit for this exercise, make sure you take into account the previous discussion of factors involving microclimate and include them in your analysis. OBJECTIVE: Determine the most comfortable place outdoors to sit and wait for a class, given today’s weather. BACKGROUND DATA: Find a computer with Internet access and fill in the following information for the current weather conditions for Mesa, Arizona. (Alternatively, your instructor may direct you to obtain this information from the MCC Red Mountain weather station, if it is in operation at the time of your class. The station is located on the roof of the Palo Verde building. The data display is instantaneous, and can be found in a glass case on the second floor of Palo Verde, directly across from the Instructional Support office.) Some of the information you can fill in based on your own observations (such as current weather (rain, dust, etc.) and cloud cover). Date Time Current Air Temperature Current Dew Point Temperature Current Atmospheric Pressure Current Wind Speed and Direction Current Weather Observations Estimated Current Cloud Cover 8 Author: Dr. J. Johnson 2005 Name________________ Exercise 5, Part 2 SPECIFIC OBJECTIVE: Given the current weather conditions, write a paragraph below what factors will constitute a ‘comfortable’ outdoor environment. (For example: Will you need a cool place or a warm one? Shelter from the wind? Be specific.) HYPOTHESIS: Describe what you feel will contribute to making a comfortable microclimate outside today. What will you look for when you head outside? Remember, you do not need to limit yourself to designated sitting areas (existing tables and chairs) – you can choose any place you feel meets your criteria for a comfortable microclimate. DATA COLLECTION: Head outside with your group to scout out potential sitting areas. You will need to select three DIFFERENT sites at which to collect data. At each site, you will complete a detailed analysis of the microclimate and write a discussion statement about its climatic comfort level. Make sure you pay attention to details, make your measurements carefully, and write your statement thoroughly, taking into account all of the microclimate factors outlined at the beginning of this exercise. Every group member needs to have experience with each of the instruments. Rotate instruments among group members as you move from site to site, and make sure that every group member is included in the process. 9 Name________________ Exercise 5, Part 2 SITE #1: Where is this site? (Be detailed – your instructor should be able to go directly there based on your directions.) Why do you think it might be a good place to sit and wait? Measure and record the following data for this site. (If you are unable to use the soil probe, record N/A). Surface Temperature: #1___________________ #2___________________ AVERAGE:_______________ #3___________________ Soil Temperature: ________________________ Wind Speed: #1___________________ #2___________________ #3___________________ Dry Bulb Temperature: ___________________ Wet Bulb Temperature: ___________________ Wet Bulb Depression: ____________________ Relative Humidity: ______________________ Dew Point Temperature: __________________ 10 AVERAGE:_______________ Name________________ Exercise 5, Part 2 Describe in DETAIL the factors influencing microclimate at this site. 11 Name________________ Exercise 5, Part 2 SITE #2: Where is this site? (Be detailed – your instructor should be able to directly there based on your directions.) Why do you think it might be a good place to sit and wait? Measure and record the following data for this site. (If you are unable to use the soil probe, record N/A). Surface Temperature: #1___________________ #2___________________ AVERAGE:_______________ #3___________________ Soil Temperature: ________________________ Wind Speed: #1___________________ #2___________________ #3___________________ Dry Bulb Temperature: ___________________ Wet Bulb Temperature: ___________________ Wet Bulb Depression: ____________________ Relative Humidity: ______________________ Dew Point Temperature: __________________ 12 AVERAGE:_______________ Name________________ Exercise 5, Part 2 Describe in DETAIL the factors influencing microclimate at this site. 13 Name________________ Exercise 5, Part 2 SITE #3: Where is this site? (Be detailed – your instructor should be able to directly there based on your directions.) Why do you think it might be a good place to sit and wait? Measure and record the following data for this site. (If you are unable to use the soil probe, record N/A). Surface Temperature: #1___________________ #2___________________ AVERAGE:_______________ #3___________________ Soil Temperature: ________________________ Wind Speed: #1___________________ #2___________________ #3___________________ Dry Bulb Temperature: ___________________ Wet Bulb Temperature: ___________________ Wet Bulb Depression: ____________________ Relative Humidity: ______________________ Dew Point Temperature: __________________ 14 AVERAGE:_______________ Name________________ Exercise 5, Part 2 Describe in DETAIL the factors influencing microclimate at this site. 15 Name________________ Exercise 5, Part 2 ANALYSIS: Write a statement about each of your three sites detailing the microclimate at each site. You should include information about the surface and air temperatures, humidity, and wind characteristics. Discuss how these measurements varied from the current conditions of the control station (data collected from the Internet or the MCCRM station). Your discussion should include an analysis of the factors controlling microclimate at each site, and an evaluation of how these factors ultimately influenced the data that you collected. 16 Name________________ Exercise 5, Part 2 ANSWER TO OBJECTIVE: Taking into consideration the data you collected and the sites you observed, discuss which site is ultimately the most comfortable place to sit outside today. Why did you choose this site? FORWARD THINKING: Will this site usually be a comfortable place to be at this time of day? Was today’s weather typical? What do you think the microclimate would be like at this place during other times of day? What about at other times of the year? FINAL ASSESSMENT: What could be changed about your site to make it MORE comfortable? (HINT: “Nothing, it’s perfect,” is NOT an answer.) Is there currently a table or bench in this place? If so, have you seen it being used very often? Why or why not? If not, should there be one, and would it be used? 17

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