Check Monthly Means and Maximums
This website gives the monthly mean and maximum UV Indicies for the 58 forecast cities in the form of a map (just like the daily UV Index forecast map. A reporting city might have a range of readings from a maximum of 12 to a minimum of 3. The mean rating would be the average rating over a month.
Take a look at the maps for January. First read the monthly mean, and then look at the monthly maximum. What do you see? How do you explain the differences?
Now, mentally divide the United States into three horizontal sections going east-west across the country. Roughly, you'll have the northern third of the country (including Alaska), the center section, and the southern section (including Puerto Rico and Hawaii). Keep those divisions in mind.
Take a look at the data for the other months of the year. What do you see happening to the data for the mean UV Index reading and for the maximum reading? Can you make any general statements about the three sections of the country? Where and when would you be most likely to enjoy the outdoors without a high risk of UVB radiation exposure? How do you explain these findings?
If you would like to try a little data analysis on your own, follow these steps. THIS ACTIVITY ASKS YOU TO CHECK A WEBSITE EVERY DAY FOR A WEEK OR LONGER.
a. table: http://www.cpc.ncep.noaa.gov/products/stratosphere/uv_index/bulletin.txtb. map: http://www.cpc.ncep.noaa.gov/products/stratosphere/uv_index/uvi_map.gif
Collect information to answer the question, " What was the average UV Index forecast for your chosen city or cities during a certain period of time?"
1. Print this graph, or use a piece of graph paper to construct your own.2. Choose two or three cities from the 58 reporting stations on the UV Index. Each day, check the UV Index forecast for those places, and chart the reading on your graph. You may wish to use a different color for each city, or you may want to make a separate chart for each one.
3. After you have charted these data for a period of time, try a little data analysis! Using what's called measures of central tendency, figure out the "average" UV reading for a city for this period of time. Calculate the mean, median, and mode for each of these places.
a. Click here to find out how to calculate the mean
b. Click here to find out how to calculate the median
c. Click here to find out how to calculate the mode
4. Once you have calculated the mean, median, and mode for your data, look to see how much they differ from each other. They may not be very close to the same number, depending on the data. Describe which one seems to be the most accurate answer to the question, "What was the average UV Index forecast for your chosen city or cities during the period of your recordings?"
Written by Susan K. Cowles, Oregon Weather Project, OASIS, 1998
