METR 104: Our Dynamic Weather (Lecture w/Lab) Lab Exploration #2: Connections between Solar Radiation & Temperature Part I: Describing & Plotting Data Dr. Dave Dempsey Dept. of Geosciences SFSU, Spring 2012

(5 points)
(Lab Section 1: Wed., Feb. 15; Lab Section 2: Fri., Feb. 17)

Prior Knowledge Required. Before starting this lab activity, you should know the meaning of these terms:
• angle (a measure of the degree of "spread" between two intersecting lines)
• down (the direction in which gravity pulls, toward the center of the earth)
• zenith (the point infinitely far away directly overhead ["up"], directly opposite "down")
• perpendicular (at an angle of 90° to, at right angles to)
• normal (in the context of this subject, another word meaning perpendicular)
• horizontal (oriented in a direction perpendicular to down)
• horizon (the points far away where sky meets earth in the absence of obstructions)
• zenith angle (angle between the zenith and the sun)
• sun angle (angle between the sun and a horizontal surface)
• radiative intensity or flux (rate at which radiative energy strikes a unit of surface area)
• insolation (intensity of solar radiation striking a horizontal surface)
• midlatitudes (latitudes between 30° and 60°, in both hemispheres)
Learning Objectives. After completing this activity, you should be able to:
• Explain the meaning of several selected columns of solar radiation data from a file downloaded from the National Solar Radiation Database 1998-2005 Update Web site.
• For one-hour average observed solar radiation intensity (flux) data, decide which type of plot vs. time (scatter plot, line plot, or bar chart) best represents the nature of the data.
• Plot the data on a blank graph, and add appropriate plot title, axis labels, tick mark labels, and (if necessary) a legend.
• Describe the primary features of the plotted data.
Materials Needed. To complete this activity, you will need:
I. Instructions

The General Idea: After being introduced to the solar radiation data above, you will work collaboratively to decide how best to configure graphs showing plots of solar radiation data vs. time for each of two days. You will then label your own graph, plot selected data, and describe the plotted patterns.

More Detailed Instructions:
1. Form a collaborative group.

1. The instructor will assign you to a group of (in most cases) three students.

2. Introduce yourselves.

1. At least one of you will create a graph of some solar radiation data recorded at Hanford, CA on December 16, 1998, and at least one will create a similar graph of similar data for Hanford, CA recorded on May 22, 1999. Decide among yourselves who will take each day.

2. If only one member of your group is plotting data for one of the days, that person should plot both the "extraterrrestrial radiation" and "measured global" data vs. time, on the same graph.

If two members of your group are plotting data for one of the days, then both should plot the "extraterrestrial radiation" data, and one should plot the "extraterrestrial radiation normal" data while the other should plot the "measured global" data (in each case, on the same graph as the "extraterrestrial radiation").

3. Agree upon how the graphs should be configured. (All graphs should be configured in the same way, except for details of the graph title and legend.)

1. You will be plotting two quantities (from the same day) on your individual graph. Based on the nature of the data (e.g., they consist of one-hour averages), decide which of the following types of plot would best present both of the two sets of plotted data on your graph: scatter plot, line plot, clustered column plot, or superimposed (not stacked) column plot.

2. Decide how best to title both the graph and each axis, and decide what information the legend should contain. [Strong suggestion: in the graph title, put key information common to both plots on the graph. In the legend, put information that tells how the data in the two plots differ. Keep the titles and legend brief but still as understandable to others like you a few hours before you started this lab. Hint: "ETR" and "Measured global" don't cut it!]

3. Decide (a) what the starting value on each axis should be and (b) the range of values represented on each axis. (These choices also determine the value represented by each horizontal and vertical line on the graph. [Strong suggestion: choose values so that the increment between labeled lines is a nice, round number. This makes it much easier to interpolate plotted values between line labels.]) Label the lines along each axis.

4. Plot the two sets of data on your graph.

4. Describe (in writing) the primary features of the individual plots on your own graph. (As guidance for what such a description should include, recall the key aspects included in our description of the daily temperature cycle.)

II. Final products. When we're done, you should turn in: