Course: ES 110L Introduction to Environmental Science Lab Unit: Climatology Content: Weather and Climate Data

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1 Unit: Lab #3: Weather and Climate Data Goals The purpose of this lab is to introduce the role climate plays in our environment by looking at weather patterns. Introduction Image taken from Wikipedia.com No one could dispute that climate plays a vital role in environmental conditions. The great biological diversity of a rainforest is undoubtedly linked to the warm moist conditions of the area. A desert with all its well adapted flora and fauna are a direct result of the dry conditions. Just as environmental science is, in loose terms, the study of the environment s effects on us as well as how we affect the environment. Similarly, climatology is the study of how the climate affects us and how we are affecting our climate. Weather vs. Climate Weather is the condition of the atmosphere at a particular time. It is analogous to a snapshot of what is going on outside at any particular time. To describe the weather, you might record the temperature, sky conditions, barometric pressure and relative humidity. In contrast, climate is what you get when you take an average of the weather in a particular place over a long period of time (usually 30 years, sometimes more). If we say a place has a sunny climate, we mean that even if it rains once in a while, it tends to be sunny far more than rainy. Describing the climate usually requires that we average the weather observations over many years. These averaged numbers are statistics and are used to describe the climate of a location. It is easy to see why the terms "weather" and "climate" are often misused even by people trained in the study of meteorology. In this lab we will learn how to access weather and climate data from the internet. Graphs will be used as a tool to display and interpret our data. Below is a short review on graphing that will help you get the most out of this exercise. Notes on Graphing A graph can be created when one has simultaneous observations for two or more variables. For example, suppose we record the ambient air temperature (temperature of the surrounding air) and the time of observation every hour for 48 hours. You could create a graph which shows how the temperature varied with time since you know both the temperature and the time for every observation you made. If you had merely recorded the temperature and not the time, no such graph would be possible as you would only have made observations for one variable. Environmental Science Laboratory 110L New Mexico State University, Department of Agronomy and Horticulture 1

2 Unit: By convention a graph consists of the following: Axes two perpendicular lines; one horizontal, one vertical, joined at the origin The horizontal axis is the x-axis and is associated with the independent variable (the variable which is thought to influence the other variable). The vertical axis is the y-axis and is associated with the dependent variable (the variable which is influenced by the independent variable). Continuing from the example from above, we would choose time as the independent variable and plot it along the x-axis since it is much more likely that time influences air temperature than air temperature influences time. Title The graph should have a title which conveys information concerning the content of the graph. Where relevant, the source of the data should be indicated. Axes Each axis should be labeled to indicate the variable being graphed. The units MUST be included. Axes must be scaled to ensure that each data point is placed correctly in relation to all other points and that all of the points fit on the graph. Graphing packages, like those in Excel, typically automatically generate a scale for the data. However, you may need to adjust the scale for a better fit. Time series data are commonly presented as two kinds of graphs: line graphs and bar graphs. Line graphs should only be used where each point on the graph relates to the magnitude of the variable under consideration at a point in time (e.g., graphs of temperature, relative humidity, wind speed, etc.). Graphs of variables such as daily rainfall, which represent a magnitude over a period of time, are more appropriately graphed using a bar graph. Pre-lab Questions and Resources 1. Please download the data file named Lab 3 Data.xls provided on the course website at 2. Use the internet to investigate the climate s role in your course of study (you might be surprised). Environmental Science Laboratory 110L New Mexico State University, Department of Agronomy and Horticulture 2

3 Unit: 3. Read through the following article considering the solutions presented for global warming. Key Words Climate, Weather, Graphing Objectives 1. Define key words shown in bold. 2. Learn to calculate and graph data using Microsoft Excel. 3. Use Microsoft Excel to look for patterns in graphed climate data. 4. Prepare a lab report, including graphs, on your findings. Procedure Part I. Obtaining Weather and Climate Data from the Internet Local National Weather Service (NWS) Offices are responsible for issuing weather forecasts, certain watches, and all warnings. In addition, they issue aviation forecasts, take weather observations at the ground and with weather balloons, and record climate data for the region. Start by exploring the website of our local NWS office, located in Santa Teresa. The website is: Find the monthly weather summary for El Paso, Texas for July Hint: On the left hand side of the screen, click on local under the heading Climate. Then answer the following questions: 1. What was the high temperature in degrees Fahrenheit (HIGHEST)? 2. On what date did this occur? 3. How many days above 90ºF occurred (DAYS MAX > 90)? 4. How much precipitation in inches fell in the month of July (TOTALS)? 5. On what date did the highest wind gusts occur? 6. What were the speeds, in miles per hour and the directions, in degrees, of these gusts? Environmental Science Laboratory 110L New Mexico State University, Department of Agronomy and Horticulture 3

4 Unit: Our region experienced abnormally dry conditions this summer. The National Drought Mitigation Center produces weekly maps depicting the status of drought conditions across the United States. The website is: Explore their website to answer the questions below: 7. Which (if any) states currently show D4 or Exceptional drought conditions? 8. How does this compare to conditions in early summer (June 13)? Hint: Click on Archive at the top of your screen. Part II. Graphing Climate Data Many people in New Mexico are claiming that winters are not as cold as they used to be. A very simple way to assess whether there has been any warming trend in winter temperatures is to construct a graph. To do this, you need to locate and download temperature data from the internet. The world s largest archive of climate data can be found at the National Climatic Data Center in Asheville, NC. Their website is: Due to the lengthy process of accessing and downloading the data from this site and because we do not want to crash their server with multiple requests at the same time, we have already done this for you. The file (NMSUclimate.xls) can be found on the class webpage at: Access this file and complete the following activities: 9. In this exercise we are interested in temperature through time, i.e. time is the independent (x) variable and temperature is the dependent (y) variable. Construct a line graph using Excel. We are using a line graph in this instance because temperature measurements are taken at a point in time (even though they were eventually averaged together to create a monthly value). Use the above graphing guidelines. Be sure to include appropriate titles and labels. Include your graph with your lab report. Environmental Science Laboratory 110L New Mexico State University, Department of Agronomy and Horticulture 4

5 Unit: The climate at a place is often compared to the Normal. The normal is the average of 30 years of data for a particular phenomena, in this case temperature. Calculate the Normal (mean temperature) for the 30 year period This is calculated by adding up all of the values of interest and dividing by the number of observations. Remember for the normal we are interested in 30 years ( ), not all the years. This can be easily done in Excel by using the Average function. 10. What is the value of the Normal? 11. Was January 2006 higher or lower than normal? 12. Next, calculate the mean or average temperature for each period ( ; ; ). Record your results in the table below: DECADE MEAN TEMP 13. Do you agree that January temperatures are getting warmer? Explain the basis for your answer in a couple of sentences (look at the trend through time). Calculations and Data Presentation Perform all calculations and prepare all graphs as instructed in the procedure section of this lab. Questions Answer all questions included in the lab procedure section. Important Information Do not forget to submit your lab report by to Sylvia Nemmers (snemmers@nmsu.edu) or Hernan Miranda (hmiranda@nmsu.edu) by 5 p.m. on Sunday Sept. 23, Environmental Science Laboratory 110L New Mexico State University, Department of Agronomy and Horticulture 5