Sun Angle and Insolation Intensity

Before starting....

Before beginning this activity make sure you have read through ***. Review the important terms and concepts at the end of the chapter. A look at the chapter review questions will be helpful as well.

Getting started .......

In this exercise you will compare and contrast the spatial and temporal variation in noon sun angle and insolation intensity at three locations. Gather the data below using the NOAA Solar Position Calculator and input the answers into the appropriate field. Once you have collected all your data answer the questions below.

Collect the data below by going to the NOAA Solar Position Calculator. There are directions for using the  Solar Position Calculator at the bottom of its web page but here are some additional ones to get you started.

1. For city: Use the drop down menu arrow button to set it for "Enter Lat/Long ->"

2. Lat and Long: Obtain the latitude and longitude for each station by using the links below. Type in the degrees, put zeros in the minutes and seconds. Make sure to use a minus sign in the degrees box if your station is in the Southern or Eastern Hemisphere.

3. For Time Zone: set "Offset to UTC" to 6 and "Daylight Saving Time" to No.

4. For Month and Day: Use the months and days in Table 1 below.

5. For Year: set to 2001

6. For Time: Set the time as 12:00:00 for the 24hr option

Part 1 Data Collection

Resolute, NWT, Canada  Latitude; Longitude 

Stevens Point, WI           Latitude; Longitude 

Guatemala, Guatemala     Latitude; Longitude 

Part 2  Analysis

1. Which of the three locations above experiences the greatest change in sun angle throughout the year?

2. In general, will locations closer to, or farther away from, the equator experience greater changes in sun angle throughout the year?

3. Based on the data above what effect does sun angle have on radiation intensity at the earth's surface?

4. What effect might the amount of change in noon sun angle at these two cities have on their respective annual temperature ranges  (difference between maximum monthly temperature and minimum monthly temperature)?

5. a. Would the sun appear to the north or south of an observer at Stevens Point and Guatemala City on June 22?

b. On Dec. 22 ?

6. Why is there a difference in the direction that the sun appears in at Stevens Point and Guatemala City over the course of a year?

7. On Dec 22 at Resolute the solar elevation is a negative number. What does this mean and why does it occur?