Activity 2: Shedding Light on the Weather with Relative HumilityNovember 7, 2007 through November 14, 2007 |
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In this activity we will:
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Get the data from your teacher. This data is collected every hour by weather stations at airports. It is often reported in the local newspaper. You may also get the data for Dallas, Texas from the link below for any given DAY. http://weather.dallasnews.com/cgi-bin/findweather/getForecast?brand=dallasnews&target=dallasnews&query=75251 Note: If your paper does not report the data your class might email them and ask that they do so as a public service. |
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As a warm up, discuss what time of day you think it gets the hottest? When do you think it gets the coldest? Key it in your home screen and share with your partners/teacher/class. To do this press  and then clear off the home screen with a  . Remember to just space over with __ from the  [TEXT] screen recalling that you press  on Done when you are full or finished. Don’t press  since the computer will wait to evaluate what you said and your are not ready for that! |
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To enter the data we need to go to the List Editor by pressing  |
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Now we need to decide what names to use for the lists that contain the hour that the data was collected, the temperature that was read at that hour and the relative humidity. We suggest HOUR, TEMP, and RH. You may use any names that you feel appropriate, but you are limited to 5 characters and you must start with a letter. It is best if the whole class comes to consensus on the names. Find the alphabet and key in the names. Move over to the next list and repeat until you have all three as shown. The alphabet mode is accessed by pressing  [TEXT] pressing on Done when you are. |
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| Let’s plot the data now. You will need to set the plot up by pressing [PLOT] and then telling what you want. Now we need to tell the computer what type of plot you want. If we are looking at the hour and the temperature we probably should not connect it, but you might want to. The unconnected version is the Scatter Plot. Select that with the softkey for SCATTERPLOT which is .Now you are asked to select the list that contains the Independent variable. Since the people read the weather station data every hour the HOUR is the independent variable, x. Move to the list for HOUR and select it by pressing . You could also pick the number or letter in front of it. Lists are accessed by pressing  . Don’t forget to set the Window with a ZoomStat. Press  then selecting option 7.How would you design the experiment so that TEMP was the independent variable? |
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| Examine the graph. Trace along it. Do you see the sunset? The sunrise? When was it the maximum temperature? The minimum? |
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| Press [PLOT] to set up the plot of RH vs. HOUR. Repeat the process above. You can just set up the second plot for this. Don’t forget to adjust the Window and turn off Plot 1 to see the pattern. |
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| Examine this plot. Do you see the sunset? Sunrise? When did it get the hottest? The coolest? Do you see the hours? Trace along the HOUR, back and forth. | 
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| You will need to go to [PLOT] and switch back to the first plot, resetting the Window with ZoomStat as before. To turn the Plots on and off from the Y= editor, just move your cursor to the top and press to turn on or off. Dark is on, as you can see to the right which has Plot1 on. |
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Press  to check to see if your plot of TEMP vs. HOUR is still active. If you have trouble, check with another student in your group and see how she did it.Let’s put in the sunrise and sunset times. Should we draw a Horizontal or Vertical line to do this? |
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| Return to the Home Screen and clean yourself up by pressing [QUIT] . Now chose the DRAW tool for the line you need. Make sure you do this from the HomeScreen so we can put in the exact time for the sunrise and sunset. Get these values from your teacher. Press  and then select the tool (either highlight it and or press the number in front of it). |
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| Now you are on the Home Screen and the computer is waiting for you to key in the time for the sunrise or sunset. Since the sunrise came first key in the time your teacher gave you. Notice in the sample the sun rose at 7:05 am. Press to actually draw it. This should send you back to the plot screen. Where you correct? Did you hit “see” the sunrise in the data? |
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Do [QUIT] to return to the Home Screen to enter in the time that the sunset occurred. Call back the last line by pressing - < to edit it. On the 73, just move up  the memory stack and highlight the command and press to retrieve it for editing. Notice in the example shown, the sunset at 6:25 pm. Don’t forget to press to see the sunset. |
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| Discuss what you think happens to the temperature as the sun comes up or sets. Explain how the plot shows this. If other teams have done different days, is the pattern the same. What other factors could be involved. What city did the data come from? Would it be different on the ocean or a lake, or in the mountains, on a prairie, or in the desert? What about rain, fronts coming into the area, cloud cover? |
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What about relative humidity? Set up the plot for RH vs. HOUR. Don’t forget to go to  to turn off Plot1 |
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Reset the Window for the data using ZoomStat. Press press  . |
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| Place the sunrise and sunset times back on the graph. Just return to the Home Screen [ [QUIT]]and use the methods mentioned above to retrieve previous commands. This time you don’t need to edit, but you will need to do it twice, once for the set and once for the rise. |
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| Do you see the relative humidity react to the changes? Do you think it is the sunset or the cooling that causes the change? What about when it heats up after sunrise? What happens to the relative humidity? What is relative humidity? What was the dew point for that day? What does that have to do with it? |
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Look both plots now. Turn Polt1 back on from the  area. |
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We will need to reset the Window, but let’s do it manually this time. Press  and adjust the values. In this case x is the hour but y will be either the temperature or the relative humidity. You will see this type of graph on may high stakes assessments so this will be good practice. We did help ourselves by using boxes for the temperature and + for the relative humidity. Note that the relative humidity can range from 0 to 100 while the temperature range will vary depending on the season. In January we could go from 10 to 60 but in August we could be 70 to 110 depending on the area you get the data from and the units used for the temperature. See the sample Window to the right. Set yours as you think best. Don’t worry since you can edit it if you are unhappy with the results. |
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| Press to get a look. Adjust the Window if you like. What do you see going on? Discuss what happens as you go through the 24 hours. Place the sunrise and sunset back on the screen if you don’t “see” them. Notice on the Plot shown we have a temperature of 57 degrees Fahrenheit at 11 am. |
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| Now set up Plot3 as shown to see the relationship between the relative humidity and temperature. Don’t forget to go to the Y= Editor to turn off the other two Plots and reset the Window either manually or with the ZoomStat. Press [STAT PLOT]  to start. |
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Do you see a pattern when you look at the Plot by pressing  Move over the data with   . Discuss. |
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| When you hear reports about the temperature in Chicago what temperature are they using? Is it the maximum, minimum, mean, mode, median? Identify these values for your temperatures. Press to see the data. Max = Min = Mean = Mode = Median = |
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The computer will give you most of these values using 1-Var Stats. To get this, return to the Home Screen and clean up [ [QUIT] ]. Then press  to select 1:1-Var Stats from the CALC Menu. |
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| Now you need to tell the computer which list you want to analyze. Do this by accessing the list of list by pressing and selecting the list for TEMP. Press to pick the list and to make it go. |
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| Look at the results. How did you do? How would these values change with location or season? Which would you use to report the temperature of the day for your city? Repeat this investigation later in the year. Do things change? Relationships? |
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