METR 104:
Our Dynamic
Weather

(Lecture w/Lab)
Lab Exploration #2:
Connections between
Solar Radiation & Temperature
Part II: Exploring
& Interpreting Data
Dr. Dave Dempsey
Dept. of Geosciences
SFSU, Spring 2012

(10 points)
(Lab Section 1: Wed., Feb. 15; Lab Section 2: Friday, Feb. 17)

Prior Knowledge Required. Before starting this lab activity, you should know the meaning of the words listed below: In addition, you should know these facts: And finally, you should be able to: Learning Objectives. After completing this activity, you should be able to: Materials Needed. To complete this activity, you will need:

I. Introduction. Forecasting temperature is one of the most common and useful aspects of weather forecasting. There are various strategies that people use to forecast temperature over the next several days, but modern professional weather forecasters do it by applying their understanding of the underlying physical causes of temperature change to current and recent observations of weather conditions, in a largely quantitative way. In this lab, we will begin to explore some of the physical processes that cause temperature to change.

Almost everyone attributes variations in temperature over the course of a day at least partly to variations in solar radiation (though of course there are other influences, too). Hence, we will start by exploring observations of solar radiation and try to make connections between those observations and observations of temperature at the earth's surface. In particular, in Lab #2, Part II, we will access, describe, and try to explain features of observed solar radiation data at several locations, and look for connections between observed patterns of temperature and solar radiation over the course of a day.

II. Instructions.
  1. Form teams that will conduct the investigations, in collaboration with other teams.

    1. The instructor will assign you to a team of several (generally three) people responsible for sharing the work of the investigation. Introduce yourselves.

    2. Each team member will be responsible for conducting a different part of the investigation (Section II.C. below) and for explaining the results to the other team members so that they can also explain them.


  2. Divide the three tasks listed below among yourselves. Your team must do all three.

    1. General Tasks (see details for each task in Section C below):

      1. Compare observations of insolation at the earth's surface in late May and mid December, at the same (midlatitude) location. Also compare each of them to the corresponding temperature observations at the same location over a full 24 hours.

      2. Compare observations of solar radiation intensity at the top of the atmosphere (i) on a surface normal to (perpendicular to) the sun's rays (that is, directly facing the sun) and (ii) on a horizontal surface.

      3. Compare observations of insolation (i) at the top of the atmosphere and (ii) at the earth's surface, on the same day and at the same (midlatitude) location.


  3. Form new, temporary "task-focused" teams, and collaborate to carry out and reach consensus about your task.

    1. Your instructor will assign each person on your original team to another, temporary team consisting of several people from other teams working on the same task as you are. Introduce yourselves.

    2. Address the points listed below that apply to your particular task.

      Task B.1.a. (as defined in the Section B.1.a. above):

      1. You have been provided with two meteograms for Hanford, CA, each spanning part of one day and all of the next. One starts on December 15 and runs through December 16, 1998 (local time), the other on May 22 and runs through May 23, 1999. On the meteograms the time is labeled in UTC (that is, the standard time in Greenwich, England), not local standard time.

        On each meteogram, identify and label some key local standard times, such as midnight, noon, sunrise and sunset. [On December 16, 1998, the sun rose at Hanford at 7:03 am and set at 4:45 pm. On May 22, 1999, the sun rose at 4:44 am and set at 7:04 pm. (On the Web, a source of this information is Naval Oceanography Portal's Sun or Moon Rise/Set Table for One Year, at http://www.usno.navy.mil/USNO/astronomical-applications/data-services/rs-one-year-us.)]

        For each meteogram, as best you can, describe the pattern of temperature over the course of a 24-hour day on December 16, 1998 and on May 22, 1999 (local time). (For example, when (Pacific Standard Time [PST]) is the temperature at a minimum, when does it reach a maximum, how does it behave between maximum and minimum points, etc.)

      2. You also have two plots of insolation at the earth's surface recorded at Hanford, CA, for December 16, 1998 and for May 22, 1999. For each plot, describe the pattern of insolation over the 24-hour day.

      3. Identify ways (if any) in which the pattern of insolation observations appears to "explain" the pattern of temperature observations, and ways (if any) that it doesn't, at least not very satisfactorily. (Comment on what you mean by "explain" in this case.)

      4. Compare the insolation at the earth's surface for the two time periods, noting similarities and differences between them. Pose possible explanation(s) for the difference(s) (if any), citing any supporting evidence that you can think of. What other information (evidence) might help you test your explanation(s), and how would it help you test it (them)?

      Task B.1.b. (as defined in the Section B.1.b. above):
      1. You have been provided with two graphs showing plots of observed solar radiation intensity (a) on a surface normal to the sun's rays and (b) on a horizontal surface, both at the top of the atmosphere, at Hanford, CA. One graph shows these solar radiation intensity observations for the period from (roughly) midnight to midnight on December 16, 1998, while the other shows the same things from (roughly) midnight to midnight on May 22, 1999.

        On the graph for December 16, 1998, note the similarities and differences between the two plots shown. Pose possible explanation(s) for the difference(s), and cite any evidence to support for your explanation(s) that you can think of. What information might help you test your explanation(s)? Repeat for May 22, 1999 if your explanation(s) and information to test the explanation(s) are any different for that day.

      2. Compare the Hanford, CA observations of solar radiation intensity on a surface normal to the sun's rays on May 22, 1999 with those on December 16, 1998. Pose possible explanation(s) for the difference(s), if any. What information (evidence) might help you test your explanation(s), and how would it help you test it (them)?

      3. Compare the Hanford, CA observations of insolation at the top of the atmosphere on May 22, 1999 with those on December 16, 1998. Pose possible explanation(s) for the difference(s), if any. What information (evidence) might help you test your explanation(s), and how would it help you test it (them)?

      Task B.1.c. (as defined in the Section B.1.c. above):
      1. You have two graphs that each show plots of insolation at (a) the top of the atmosphere and (b) the earth's surface, observed at Hanford, CA. One graph shows these solar radiation intensity observations for the period from midnight to midnight on May 22, 1999 (standard time), while the other shows the same things from midnight to midnight on December 16, 1998.

        On the graph for December 16, 1998, note the similarities and differences between the two curves. Pose one or more possible explanations for any differences, citing any supporting evidence that you can think of. For each explanation, what other information might help you test it, and how? Repeat for May 22, 1999 if your explanations and information to test them are any different for that day.

  4. Rejoin your original team members, share your observations and possible explanation(s) with them, get feedback from them, and summarize your findings and ideas in writing, illustrated with the graphs.

    1. Your team should prepare and turn in a single report that addresses the points above for all three tasks. Include all relevant graphs, labeled as needed so that you can refer to them easily in your report. Clearly identify who was responsible for each section of the report.

    2. Your score for this lab will be based on how well the report as a whole addresses the points associated with each task above (50%) and on how well you addressed your part of it in particular (50%). The score will depend on how thoroughly and clearly you address each point, how well you support possible explanation(s) that you propose to explain your observations, and on how well your proposed additional information might help you test your possible explanations (though you don't actually have to perform any tests).


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