Part 2—ACQUIRE Geographic Resources
Step 1 – Download and Install My World GIS
- Open the My World homepage in a new window and click the Get the Software! button in the upper right hand corner of the page.
- Look for the FREE 45-DAY TRIAL VERSION box and click the link to PASCO's My World Trial Registration Page.
- A new web browser window opens and displays the PASCO registration form. Complete the form. Make sure to fill out the required fields shown in red. Then click the Submit button at the bottom of the page.
- A My World GIS™ version 4.x Trial Version Installer loads. Click on the "Start Installer for..." button. This will start the My World GIS installation on your computer.
- Follow the on-screen instructions to install My World GIS on your computer.
Note: You may want to return to the My World GIS website later and explore its resources.
Step 2 – Gather Needed Equipment
- With a clipboard and notepaper, walk around your campus and make a list of the major types of landcover and surfaces you see. Think about which ones you would expect to be warmer or cooler than others.
- Acquire an instrument that measures temperature. Use the most precise instrument available to you. Familiarize yourself with how to use it correctly and consistently.
- Practice taking the temperature at several locations to develop the exact procedure that you will follow for taking temperature measurements. Consider the following questions as you develop your procedure:
- How far above the surface will you hold the thermometer or temperature probe?
- How many times will you take the temperature at each location?
- How will you deal with changing results (different temperatures) at the same location?
- Will your measurements be made in sun, shade, or both?
- What will you consider as the minimum area of uniform landcover for a valid location at which to measure temperature?
- Is there a minimum distance between locations that will you test?
Step 3 – Formalize Your Protocol
- Prepare a data collection table. For each location where you'll take a measurement, you'll want to gather as much information that is relevant to your study as possible. Make your table fairly large so that you'll have plenty of space to record handwritten notes at each location. If necessary, use one sheet of paper per data collection site.
These are the data collected for each location in the example study:
- Latitude (decimal degrees)
- Longitude (decimal degrees)
- Brief description of location
- Type of land cover
- Type of exposure (sun, shade)
- Surface temperature (°C)
- Date of measurement
- Time of measurement
- Write a detailed description of the procedure for collecting data. This is the protocol for your experiment. Your description should be clear enough that someone who is not working with you could take the measurements and they would be consistent with your own.
- Determine which sites will be tested. Pick a variety of surfaces, including natural (i.e. grass, bushes, dirt, water) and urban (i.e. concrete, black top, pavement) surfaces. Each surface should be homogenous for a minimum of 3 meters in each direction (at least nine square meters).
- Divide the class into lab groups. Half of the lab groups will test the first series of sites on the list (the first seven for this example), and the other groups will test the reminder of the sites (the last eight).
- Select the most precise instrument available to you for measuring temperature.
- At each location, hold the thermometer 5 cm above the ground and record the temperature. All lab groups should measure simultaneously. Record the average temperature measured by all groups at that site as well as the date and time that you started measuring the temperature. All measurements should be made within one class period for valid comparison among values.
- If you are using an infrared thermometer, hold the device such that the beam of light is perpendicular to the ground. Hold the device very steady until you get a digital reading. You may want to repeat three times and take an average to ensure accuracy.
- If you are using a standard thermometer, hold the device in one steady position for at least one minute, or until the temperature reading stabilizes. While measuring, shade the bulb of the thermometer to ensure that you are measuring heat radiated from below.
- Record the GPS coordinates of the site in decimal degrees. For North America, latitude measurements should be recorded as positive values (north of the equator) and longitude measurements should be recorded as negative values (west of the International Data Line, which runs through Greenwich, England).
For most simple hand-held GPS units, the antenna is located just above the screen. Therefore, hold the devise so that the screen is facing up and the unit is parallel to the ground. Hold the devise still in the location you are measuring for at least two minutes to get an accurate fix on your location.
- At each location, remember to also record a brief description of the location, the type of land cover present, and the type of exposure the surface is currently receiving (sun, shade, mixed).
If you have access to infrared thermometers, they are the best choice for measuring surface temperature, or heat radiating off a surface. If you don't have any in your classroom, check with your school's maintenance staff; they often have infrared thermometers for checking on heat and air conditioning systems.
Step 4 – Take Measurements and Record Data
- Collect and record data according to your protocol. Before you leave each location, double-check that you have collected valid data for each of the fields on your table.
- To work through the heat island example, download the spreadsheet (Excel 17kB Jun6 08) of temperature and land cover data and open it into Excel or another spreadsheet application.
- If you have access to a digital camera, capture and save digital images of each location. Add the photo number of each site onto the data collection chart. Later, you can link these images to your My World project file.