How does today's UV Index compare with other days in Oregon? Let's see how many days had very-high, high, moderate, low, and minimal ratings. (You may want to print a copy of this activity.)
First, read the information about the UV Index Annual Time Series.
Now, follow the link to the Oregon data for 1998.
You will see a colorful graph. At first glance, you see that in 1998 there were no days when the UV Index Forecast was "very high" for Portland, Oregon. (That should come as no surprise to residents!) You will also see that there is some variation between the "Clear Sky UV Index data (black line) and the UV Index Fcts (Forecast&emdash;blue line). We will be using the summary information about the UV Index Fcst (Forecast). It appears at the bottom right of the graph, and it looks like this for 1998:
Very High =
High =
Moderate =
Low =
Minimal =
If we add those numbers, we see that there were UV Index data for 317 days in 1998. Using that information, answer the following questions:
1. Now, make these same calculations for the 1997 Annual Time Series in Oregon
a. Percentage of days with "very-high" UV forecast __________b. Percentage of days with "high" UV forecast __________
c. Percentage of days with "moderate" UV forecast __________
d. Percentage of days with "low" UV forecast __________
e. Percentage of days with "minimal" UV forecast __________
2. Now, make these same calculations for the 1996 Annual Time Series in Oregon
a. Percentage of days with "very-high" UV forecast __________b. Percentage of days with "high" UV forecast __________
c. Percentage of days with "moderate" UV forecast __________
d. Percentage of days with "low" UV forecast __________
e. Percentage of days with "minimal" UV forecast __________
3. Look at the 1998 UV Index and Annual Time Series for 2 other cities in the United States. Where would you expect the UV Index ratings to be higher than the forecast for Oregon? Where would you expect the ratings to be lower? Make the same calculations for the two other places you have chosen.
1998 Annual Time Series for __________a. Percentage of days with "very-high" UV forecast __________b. Percentage of days with "high" UV forecast __________
c. Percentage of days with "moderate" UV forecast __________
d. Percentage of days with "low" UV forecast __________
e. Percentage of days with "minimal" UV forecast __________
1998 Annual Time Series for __________
a. Percentage of days with "very-high" UV forecast __________b. Percentage of days with "high" UV forecast __________
c. Percentage of days with "moderate" UV forecast __________
d. Percentage of days with "low" UV forecast __________
e. Percentage of days with "minimal" UV forecast __________
4. Compare your findings to the information about Oregon in 1998. Describe the similarities and differences you find in these comparisons. You may want to make a graph, write a paragraph, or describe the shape of the blue lines on the UV Annual Index for each place. How do you explain the differences between the data for these three locations? Would you predict that Oregonians are at great risk for UVB radiation during most of the year? How about people living at the other two locations you chose to investigate?
Written by Susan K. Cowles, Oregon Weather Project, OASIS, 1998
