## Maximum, Minimum, and Current Air Temperature -- Looking At the Data 

### Are the data reasonable?

![](media/image1.png){width="3.2in" height="2.1333333333333333in"}

The first step in looking at temperature data is to see if the data seem
reasonable and make sense. Students should check to see that their
values are consistent with their expectations and with recent
measurements. They should also check the relationship among current,
maximum, and minimum temperatures (T~current,~ T~max,~ and T~min)~. By
definition T~max~ must be the highest temperature for this time period
and T~min~ must be the lowest. Therefore,

> T~max~ T~current~ and T~min~ T~current~

for T~current~ at both the beginning and the end of the 24-hour period.
If these inequalities are not true, then something is wrong with the
T~max~ or the T~min~ for this day.

**Exercise 1:** Create a graph of maximum, minimum, and current
temperature for Gymnazium Dr. A Hrdlicky in Humpolec, Czech Republic for
April 1998.

> **Step 1:** From the GLOBE Home page, click on [Maps and
> Graphs]{.underline}.
>
> **Step 2:** Click on [Search]{.underline}.
>
> **Step 3:** Type in "Humpolec" and then click on [Go]{.underline}.
>
> **Step 4:** Check the box next to Gymnazium Dr. A Hrdlicky to choose
> this school, and then click on [Go]{.underline} next to "Make a
> Graph".
>
> **Step 5:** Scroll down this page and then back up to see what is here
> besides the graph.
>
> **Step 6:** Look under the list of "CURRENTLY SELECTED DATASETS". Hold
> down the control/Ctrl key (for PCs) or the command/Apple key (for
> Macs) on the keyboard and click on [Minimum Temperature]{.underline}
> to add this dataset to the graph. This is called "control click."
> Click on [Redraw]{.underline}.
>
> **Step 7:** Control click on [Current Temperature]{.underline} under
> the list of "CURRENTLY SELECTED DATASETS" to add this dataset to the
> graph. Click on [Redraw]{.underline}.
>
> **Step 8:** To change the starting date shown on the graph to April 1,
> 1998, click on the down arrow next to "1996". Click on
> [1998]{.underline}. Click on the down arrow next to "08". Scroll up on
> the list that appears, and click on [01]{.underline}. Click on
> [Redraw]{.underline}.
>
> **Step 9:** To change the ending date of the graph to April 30, 1998,
> click on the down arrow next to the current year. Click on
> [1998]{.underline}. Change the month to [04]{.underline}; change the
> day to [30]{.underline}. Click on [Redraw]{.underline}.

**Question 1b:** Do the data look reasonable?

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**Question 1b:** What would an invalid maximum temperature look like on
the graph?

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**Hint:** Compare the maximum temperature for one day with the current
temperature from the current day and the day before. Do the same for the
minimum temperature.

Another check on the reasonableness of data from a single day is to
compare them with data from other near-by GLOBE schools or other sources
of temperature data.

**Exercise 2a:** Create a map centered on Gymnazium Dr. A Hrdlicky,
showing data for maximum temperature on April 22, 1998.

> **Step 1:** Scroll down to the "Selected Schools" area. Under
> Gymnazium Dr. A Hrdlicky, click on [\[Map\]]{.underline}.
>
> **Step 2:** You will now see a map of Maximum Temperature for today's
> date. Change the date to April 22, 1998 by changing the values given
> under "Date (year, month, day)". Click on [Redraw map]{.underline}.
>
> **Step 3:** Check the writing in the bottom left-hand corner of the
> box surrounding the map to see how many schools are included in the
> map.

**Question 2a:** Are the values from these schools consistent with the
value for Gymnazium Dr. A Hrdlicky, which is in the center of the map?
Why or why not?

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**Exercise 2b:** Create a map centered on Gymnazium Dr. A Hrdlicky,
showing data for minimum temperature on April 22, 1998 and make the map
bigger.

> **Step 1:** Under the box "Datasets for this map type", click on
> [Minimum Temperature.]{.underline}
>
> **Step 2:** Click on the down arrow under "Map Size", next to "small".
> Select [medium]{.underline} from the pull down menu that appears.
>
> **Step 3:** Click on [Redraw map]{.underline}.

**Question 2b:** Are the values from these schools consistent with the
value for Gymnazium Dr. A Hrdlicky, which is in the center of the map?
Why or why not?

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

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**Exercise 2c:** Create a map still centered on Gymnazium Dr. A
Hrdlicky, showing data from a larger area for minimum temperature on
April 22, 1998.

> **Step 1:** On the bar with the magnifying glass icon next to the map,
> click on [16]{.underline}.

**Question 2c:** How many schools' data are shown? \_\_\_\_\_\_\_\_ How
many of the schools shown are in Austria? \_\_\_\_\_\_\_ How many
schools shown reported data below freezing for this date?
\_\_\_\_\_\_\_\_

### What do people look for in these data?

In climate studies of air temperature, most interest is in the averages
over various time periods and in the extreme values. On most days, air
temperature varies with the diurnal (daily) cycle of sunlight, and this
variation is often larger than the change from day to day. The exchange
of heat (energy) between the atmosphere and the surface is proportional
to the difference in temperature between the two.

Energy exchanged T~atmosphere~ T~surface~

For a day, the energy exchange is simply proportional to the difference
in the daily average temperatures of the atmosphere and surface. A
number of other energy exchanges behave similarly, so, daily average air
temperature is useful and more interesting than the details of the
diurnal variation. For most places, air temperature varies significantly
as weather systems move across the region in a succession of cold fronts
and warm fronts. The exact timing of these weather systems varies from
year so that comparing temperatures from the same day on different years
is not a good indication of climate variation. To get at year to year
changes, one must average over multiple weather systems. A month is long
enough to average out the effects of individual storms, but seasonal
variations are not averaged out.

The average temperature for a day can be estimated by averaging the
maximum and minimum temperatures for that day. Research has shown that
this estimate is generally within 0.1^o^ C of the actual average value.

**Exercise 3:** For one of the schools on the map produced in Exercise
2, find the maximum and minimum temperature values for April 22, 1998.

> **Step 1:** In the box "Click on map to:", click on the circle on the
> left side of the words "choose site" to change the response to
> clicking on the map itself.
>
> **Step 2:** Click on the data point for any school on the map itself
> to see data for this day for this school.
>
> **Step 3:** Scroll down to see the table.

**Question 3:** What is the average temperature for April 22, 1998 at
the school you have chosen?

**School Name:**
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ **T~max~** =
\_\_\_\_\_ **T~min~** = \_\_\_\_\_

T~max~ + T~min~ \_\_\_\_ + \_\_\_\_

**T~average~** = = = \_\_\_\_\_\_\_\_\_^o^ C

The monthly average temperature can be calculated by averaging the
maximum and minimum temperatures for every day in the month. The GLOBE
Visualization server can compute and display several summary data
products, including daily, monthly, and annual mean temperatures and
monthly and annual total rainfall.

**Exercise 4:** Create a table of the average monthly temperature values
for the schools currently shown on the map for April 1998.

> **Step 1:** Change the "Category" from Measurements to Summaries. To
> do this, click on the down arrow next to the word "Measurements".
> Click on Summaries in the list that appears. Then click on [Redraw
> map]{.underline}.
>
> **Step 2:** Look at the list under "Datasets in this category". Click
> on [Mean Temperature (Monthly Average)]{.underline}. Then click on
> [Redraw map]{.underline}.
>
> **Step 3:** Scroll down to the "Other Options" list. Click on the down
> arrow next to the words "Select Option". Click on [Show
> Table]{.underline} in the list that appears. You may have to scroll
> down to see the Show Table option. Click [Go]{.underline}.
>
> NOTE: If the list contains "Hide Table" instead of "Show Table" then
> the list is already being displayed at the bottom of the page. Go on
> to the next step.
>
> **Step 4:** Scroll down on the resulting page. Below the map and the
> map controls, you should see a table that shows the monthly average
> temperature and average maximum and minimum temperatures for each
> school shown on the map.

**Question 4a:** What is the average temperature for April 1998 for
Gymnazium Dr. A. Hrdlicky in Humpolec? \_\_\_\_\_\_\_\_\_\_\_ C

**Question 4b:** How does the April 1998 average temperature in Humpolec
compare with the average temperature as measured by schools in the Czech
capitol city of Praha (also known as Prague)?

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Most living things are sensitive to the extremes in temperature. This is
particularly true when temperatures go below the freezing point of water
(0.0^o^ C). Looking at the minimum temperatures reported by a school
reveals when these conditions begin and end each year.

Students can then explore relationships between the timing of these
seasonal air temperature changes and other phenomena (e.g. budburst).

**Exercise 5:** Create a graph of minimum temperature for Gymnazium Dr.
A. Hrdlicky for 1998 and a table of these data.

Note: You can also use the procedure outlined in Exercise 1 to make the
initial graph.

> **Step 1:** Find Gymnazium Dr. A. Hrdlicky in the table of data
> created in the previous exercise.
>
> **Step 2:** Make sure there is a \"check mark\" in the box next to the
> ATM-01 study site for Gymnazium Dr. A. Hrdlicky. If there is not one
> already, place one there by clicking in the empty box next to the
> school\'s name. Make sure there are no checks next to any of the other
> schools.
>
> **Step 3:** Where it says "Choose items from the table" at the top of
> the table, click on the down arrow next to the words "Select Option".
> Click on [Make a Graph]{.underline} in the list that appears.
>
> **Step 3:** Click on [Go]{.underline} next to "Make a Graph".
>
> **Step 4:** In the resulting graph, change the date range to 1998 01
> 01 and 1998 12 31. Select [Minimum Temperature]{.underline}. Click on
> [Redraw]{.underline}.
>
> **Step 5:** Under "Other Options" select [Show Table]{.underline}.

**Question 5a:** What was the last day in the spring of 1998 when the
temperature at Gymnazium Dr. A. Hrdlicky was below 0.0^o^ C?
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

**Question 5b:** What was the first day in the fall of 1998 when the
temperature at Gymnazium Dr. A. Hrdlicky went below 0.0^o^ C?
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Student researchers can compare temperatures, average temperatures, and
temperature extremes between different schools or locations. In
comparing schools, they should consider the different variables that
influence climate, such as latitude, elevation, proximity to large water
bodies, and other geographic factors. Also, most large cities are warmer
than the surrounding countryside.

The GLOBE Visualization system includes a powerful search engine to help
students identify schools based on geographic location, elevation, and
amount of data collected in each of the GLOBE investigations. These
tools can be used to locate schools whose data can be used in student
inquiry projects.

**Exercise 6a:** Find a school in the United States that is within +/-
one degree of latitude of Gymnazium Dr. A. Hrdlicky and that has at
least 800 air temperature measurements in 1998.

> **Step 1:** From the graph created in the previous exercise, scroll
> down to the "Other Options" list. Click on the down arrow next to the
> words "Select Option". Click on [Add or change schools]{.underline} in
> the list that appears. Click on [Go]{.underline}.
>
> **Step 2:** Scroll down to the \"Advanced School Search\" box. Click
> on the button labeled [Lat/Lon Regional Search]{.underline}.
>
> **Step 4:** Again scroll down to the \"Advanced School Search\" box.
> Under \"Regional Search\", enter 50.5 N for the [Northern
> Lat]{.underline} and 48.5 N for the [Southern Lat]{.underline}.
>
> **Step 5:** Under \"Number of Data Reports\", change the data being
> counted from total data to air temperature data only by clicking on
> the down arrow next to \"Total\" and selecting [Air
> Temperature]{.underline} from the list that appears. Enter the number
> 800 in the box to the left.
>
> **Step 6:** Also under \"Number of Data Reports\", change the Start
> Year to [1998]{.underline}, the Start Month to [01]{.underline}, the
> End Year to [1998]{.underline}, and the End Month to [12]{.underline}.
>
> **Step 7:** Click on [Start Search]{.underline}.
>
> **Step 8:** Scroll down to the table. Find the US school that is
> closest in latitude to Gymnazium Dr. A. Hrdlicky (it should be Orcas
> Island High School).

**Exercise 6b:** Create a stacked graph and a table showing daily
minimum air temperature for both schools\' in Exercise 6a from January
1, 1998 through December 31, 1998.

> **Step 1:** Place a check mark next to Orcas Island High School by
> clicking in the empty box next it. There should also be a check mark
> next to Gymnazium Dr. A. Hrdlicky.
>
> **Step 2:** Scroll back up and click on Go next to \"Make a Graph\".
>
> **Step 3:** Change the Plot Type from combined graph to stacked graph
> by clicking on the down arrow next to \"Combined Graph\" and selecting
> [Stacked Graph]{.underline}. Click on [Redraw]{.underline}.
>
> **Step 4:** Scroll down to the "Other Options" list. Click on the down
> arrow next to the words "Select Option". Click on [Show
> Table]{.underline} in the list that appears. You may have to scroll
> down to see the Show Table option. Click on [Go]{.underline}.
>
> NOTE: If the list contains "Hide Table" instead of "Show Table" then
> the list is already being displayed at the bottom of the page. Go on
> to the next step.
>
> **Step 5:** Scroll down on the resulting page. Below the graph and the
> graph controls, you should see a table that shows the daily minimum
> temperatures for the two schools.

**Question 6:** Which of the two schools in Exercise 6 had a longer time
between the last freezing temperature of spring and the first freezing
temperature of fall in 1998? In other words, which one had the longer
growing season?

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