![[dobson unit figure]](dunit.gif)
DIRECTIONS: Read each instruction carefully. Put your answers to questions on the answer sheet.
Before
we begin this activity, it is important to know the latitude and
longitude of where you live.
If you know your latitude
and longitude in degrees, write it in the boxes on your answer
sheet.
If you don't know your latitude / longitude, or to be more precise, try:
Step 1- Enter the name of your town
Step 2- Enter your latitude and longitude in degrees on your answer sheet.
Step 3- Close the NEW window using the box in the upper left corner.
DIRECTIONS: Read each instruction carefully. Put answers to questions on the answer sheet.
-Between your head and outer space is a layer of gas called ozone. As you have already learned, ozone protects you from harmful sun rays.
1. If you were able to take a giant net and collect all the ozone that is DIRECTLY above your head, how thick would the layer of gas be? Take a guess and make sure your answer is metric!
2. Convert your answer to #1 in mm, and then multiply by 100.
-You just converted your answer to DOBSON
UNITS (DU)
-A Dobson Unit is defined as a .01mm layer of ozone
at 0C and 1atm pressure. (Simply put, it is how big the ozone
layer would be at the surface and 32°F).
To better explain Dobson Unit, look at this picture:
3.
Practice converting between DU and mm of ozone at 1atm / 0 degrees
C:
(a) If I had 20mm-worth of ozone above my head, what is that
in DU?
(b) How thick in km is 5000 DU of ozone?
4. FIND OUT HOW MUCH OZONE WAS ABOVE YOUR HEAD YESTERDAY:
Step 1- Click here ---> http://jwocky.gsfc.nasa.gov/teacher/ozone_overhead.html
Step 2- Enter YESTERDAY'S date
Step 3- Enter the latitude and longitude from the PREFACE
Step 4- Press "Submit" and write the answer to Question #4 on your answer sheet.
Step 5- Close the NEW window by clicking on the box in the upper left corner.
5. On your answer sheet, take a ruler and draw a line showing how thick the ozone layer in Question #4 would be.
6a. How close were you to your original guess in Question #1?
b. Why do you think they were different, and are you surprised?
DIRECTIONS: Read each instruction carefully. Put answers to questions on your answer sheet.
-Ozone amounts are not stable, they change!
7a. Guess how long it takes ozone amounts to change about 5 DU.
b. Guess how much DU changes in one year above your head. (Simply guess what the lowest amount would be, and subtract that from the highest amount)
8. Let's find out exactly how ozone changes above your head.
Click here -----> http://jwocky.gsfc.nasa.gov/teacher/ozone_overhead.html to complete the table on your answer sheet. (The ozone amount from yesterday is simply your answer for Question #4.)
Once you have filled in the table, close the NEW window.
9a. Does ozone change more or less frequently than you thought in Question #7?
b. Is the ozone change more or less severe than your guess in Question #7?
10a. Although we have a rough idea of how ozone changes above your head, why is the chart on your answer sheet probably not the best way of finding the highest and lowest ozone values within the past year?
b. What would a scientist have to do to figure out the real range of ozone values within the last year?
DIRECTIONS: Read each instruction carefully.
Step 1- Click on -----> http://jwocky.gsfc.nasa.gov/sat.html
Step 2- Read about the satellites (and look at their pictures) to answer the questions
11. What four satellites gave us these pictures of the ozone layer, AND what years did they supply data? Fill in the chart on your answer sheet.
12. Which satellite gave you the ozone information from yesterday?
13. How high is this satellite's orbit today?
14. How long does it take this satellite to orbit the Earth one time?
15. What was unique about how the satellite in July 1996 was launched?
Close the NEW window.
DIRECTIONS: Read each instruction carefully
-Every part of the globe has different amounts
of ozone above it.
-By the mid 1980's, ozone amounts over Antarctica were so low,
that scientists called it the "ozone hole".
Step 1- Click on---> http://jwocky.gsfc.nasa.gov/eptoms/ep.html
Step 2- Find the most recent ozone hole animation (Antarctica).
Step 3- Watch the animation (replay it if you need to) and answer the questions below.
| NOTE: The black spaces are missing data, not a lack of ozone!! |
16. What dates does the ozone hole seem its biggest and worst?
17a. What appears to be the lowest ozone value given (roughly)?
b. How thick would this layer be at surface pressure?
c. Use a ruler to draw a line that shows the actual thickness of the ozone layer from Question #17b.18. Where is the lowest value on the last date of the animation?
Step 1- Note
the last date, and approximate the latitude and longitude in degrees
of the area you found in question 18.
(HINT: If you need help with the latitude and longitude
values, you can "cheat" by using http://jwocky.gsfc.nasa.gov/latlon.html )
Step 2- Close the NEW window.
Step 3- Click on----> http://jwocky.gsfc.nasa.gov/teacher/ozone_overhead.html
Step 4- Enter the latitude, longitude, and date to find out the EXACT lowest ozone value.
19. What is the exact ozone value?
Step 1- Close the NEW window
Step 2- Click on ----> http://jwocky.gsfc.nasa.gov/eptoms/ep.html
Step 3- Find the most recent Northern Hemisphere low ozone animation and play it.
20a. Is the low ozone over the North Pole worse than the South Pole?
b. Is the low ozone over either pole MORE than the low ozone over your head?
c. How do you know for sure?