Welcome to the labs for Geography 1112 (Introduction to Weather & Climate) and congratulations on finding 405 Arts & Humanities! We want you to learn, be engaged, and have fun in the labs, and this first lab will hopefully fulfill all three criteria. The goals of this lab are twofold: explore atmospheric characteristics of different places within and near GSU, and understand the geographic coordinate system using Google Earth. The three main activities are as follows:
- taking measurements in the field;
- using your specific field location to better understand the concept of latitude and longitude; and
- beginning to understand how different types of land cover can impact atmospheric characteristics (e.g., temperature).
You might be thinking to yourself or maybe asking your neighbor the following question: “What are these measurements we will be doing?” Each team (i.e., the two people sitting next to each other on one side of the table) will be given a protective case containing a weather meter, an infrared thermometer, a solar power meter, and a CO2 meter. The weather meter will be used to measure air temperature, dew-point temperature (i.e., humidity), atmospheric pressure, and wind speed. The infrared thermometer will be used to measure the temperature of the ground (or surface temperature). The solar power irradiance meter will be used to measure solar irradiance (i.e., the amount of sunlight). And the CO2 meter will be used to measure the concentration of carbon dioxide (CO2). These variables are features in future labs, and the measurements you take today will be used in those labs. Therefore, do not worry if you aren’t familiar with the variables at the present time. We simply want you to measure them and then at the end of the lab the class will brainstorm about different places had the same or different values of certain variables.
Your lab instructor will now show you how to use the four instruments, and he/she also will check to see that your instruments are working and that the variables are being measured in the following units:
- Air temperature (°C)
- Relative humidity (%)
- Dew-point temperature (°C)
- Atmospheric pressure (hPa)
- Altitude (m)
- Wind speed (m s-1 or m/s)
- Surface temperature (°C)
- Solar irradiance (W m-2)
- CO2 concentration (ppm)
In case you forgot the weather meter variables, they are provided below.
And just as a reminder, the information below shows you what you are measuring with each instrument.
You are measuring air temperature, relative humidity, dewpoint temperature, barometric pressure (i.e., atmospheric pressure), altitude, and wind speed with the weather meter.
Air temperature: dEG
Relative Humidity: r.h.
Dewpoint Temperature: d.P.
Barometric Pressure: bAro
Wind Speed: SPd
You are measuring surface temperature with the infrared thermometer.
You are measuring solar irradiance with the solar power meter.
You are measuring CO2 concentrations with a CO2 meter.
Before you are assigned your location, we want to make sure you know how to properly input the latitude and longitude coordinates into a map app on your phone. Yes, your phone can take you to a location using latitude and longitude, just like it can when you type in a street address.
Type the following coordinates into your phone to take you to the approximate location of this classroom: 33.754160, -84.386539. The first number is the latitude and the second number is the longitude
Your lab instructor will now assign each team one of the 15 locations on the map below. All locations are within approximately 1/4 mile of 405 Arts & Humanities (the black star on the map). Provided on the right side of the map and in this file are the latitude and longitude of each point. The units are decimal degrees. You will be exploring the concepts of latitude and longitude after you get back to the classroom after taking measurements at your location.
Type the coordinates into your phone and go your location. Record your measurements of air temperature, dew-point temperature, atmospheric pressure, wind speed, solar irradiance, and CO2 concentration on the data sheet provided to you. You also may want to download the image below onto your phone so that you have a back-up navigation option. If your location is a parking garage (i.e., A, F, and O), please go to the top level of the garage. If your location is at a body of water (i.e., D and M), please take your measurements as close to the water as possible without accidentally dropping the instruments in the water. In addition, let the CO2 meters take measurements for at least one minute before recording the concentration. The entire class will leave together and everyone needs to meet back at the classroom within 30 minutes of leaving. Good luck!
Hopefully all the teams have returned with good data after taking measurements at their locations. Now, one member from each team needs to go to instructor workstation at the front of the room and enter into a spreadsheet the values for the measurements you have taken. Your lab instructor will guide you if you are unfamiliar with spreadsheets. Your class will examine these data in Section 7 of this lab.
Before your class analyzes the data everyone just collected, let’s become more familiar with latitude and longitude using both Google Earth and that attractive globe on your table. Google Earth, which is not the same thing as Google Maps, is a free geographic information system (GIS) created by Google. You can download it and put it on all your devices. We have it on this PC, so go ahead and double-click the Google Earth Pro icon on your desktop.
You are now ready to start using those lines to better understand what the latitude and longitude numbers for your location actually are. In the examples below, we are using the coordinated of 405 Arts & Humanities. We want you to use the coordinates of the location where you just took the measurements. Type in your coordinates just like you did in your phone’s map app.
Google Earth will automatically zoom to your location and put a yellow pushpin (i.e., a placemark) at your location. Notice how the latitude and longitude of the location are displayed directly next to it. Lines of latitude (the horizontal white lines) and lines of longitude (the vertical white lines) also are displayed.
To make the aerial image look more realistic, turn on 3D Buildings and Terrain in the Layers section of Google Earth.
Zoom out using the slider on the right until you see both your location and the equator (if you don’t know what that is then click here). You also can use the wheel on your mouse to zoom in and out.
Go ahead and zoom out so that you can see both your location and the equator. The distance between your location and the equator, as measured in degrees, is the latitude of your location. Latitude ranges from -90° (the South Pole) to 90° (the North Pole). The latitude of the equator is 0°. Instead of having positive and negative values for latitude, latitude can be expressed as degrees from the equator in either the Northern Hemisphere (e.g., 33.754160° N) or the Southern Hemisphere (e.g., 33.754160° S). In the example below, this classroom is shown to be approximately 33.75° north of the equator.
Go ahead and move your Earth so that you can see both your location and the prime meridian. The distance between your location and the prime meridian, as measured in degrees, is the longitude of your location. Longitude ranges from -180° to 180°. The longitude of the prime meridian is 0°. Instead of having positive and negative values for longitude, longitude can be expressed as degrees from the prime meridian in either the Western Hemisphere (e.g., 84.386539° W) or the Eastern Hemisphere (e.g., 84.386539° E).
Let’s get back to downtown Atlanta and examine the environments of the locations where your class took measurements.
Click locations to download the file. This is a .kmz file, which Google Earth uses, and after you click it (go ahead and click it) the locations of the 15 sampling sites will appear in Google Earth. Take a few minutes to zoom in on the locations to see what the land cover (e.g., grass, asphalt, concrete, etc.) and the geographical settings (e.g., urban canyon, park, top of structure, etc.) are for the locations.
Your lab instructor has hopefully projected the data for all the variables at all locations onto one or both screens in the room. Please notice the three summary metrics (minimum, mean, maximum, and coefficient of variation) at the bottom of the projected spreadsheet. You should be familar with minimum, mean, and maximum, but coefficient of variation should be a new term for you. This is simply a measure of how spread out (i.e., dispersed) the values are, and the larger the coefficient of variation the more dispersed the values. Refer to the measured data and the information in locations (i.e., the local environments of the locations) to answer the questions below. Your answers to the questions will help you to better participate in the class discussion. Since this is the very first lab and you have not learned about the processes affecting all the variables you just measured, you will be assessed on your effort in answering the questions, rather than the accuracy of your responses.
- How would you describe the differences in surface temperature among the locations and why did certain locations have higher values than other locations?
- How would you describe the differences in CO2 concentrations among the locations and why did certain locations have higher values than other locations?
- How would you describe the differences in pressure among the locations?
If you used a Telaire CO2 meter (i.e., the grey one), it most likely recorded artifically high CO2 concentrations because it is need of calibration. Please let the lab instructor know what your location is if you had a Telaire CO2 meter.
Your lab instructor will now lead a discussion about your findings concerning surface temperature, CO2 concentrations, and atmospheric pressure. If there were more interesting findings concerning the other variables, then he/she will steer the dicussion towards those variables.