Overview
Roughly 75% to 80% of the earth's surface is covered with water. This has profound effects on the climate of the earth. The water absorbs massive amounts of energy from the sun. Because of the heat capacity of water (which is related to the specific heat of water) the changing amount of energy is not immediately manifest in a change in the surface temperature of the ocean. Along the same lines the water takes a longer time to lose this energy than an equal mass of (rock or soil). This causes a moderation of climates near bodies of water. Depending on the season (caused by the tilt of the earth on its axis) more or less energy pours on to the surface. This energy runs the hydrologic cycle. The sea surface temperature maximums and minimums are delayed (thermal lag) because of water's capacity to absorb and release heat.
Learner Outcomes
By completing this activity, the learner will:
Plots can be generated for any location on the image. There is a more pronounced difference if one goes from 60º N latitude to 60º S latitude. Over time, the migration of sea surface temperature becomes evident when the line graphs are compared. These plots can be printed and transparencies made from the print-outs. The plots cannot be saved to another format, but the transparencies or printouts can give a reasonable perspective of temperature zone migration over time.
The images for this activity come from the extensive resources of the University of Wisconsin Space Science and Engineering Center.
1. Open NIH image.
2. Open the latest image found here.
Note: Images that have been saved from the Internet (see Directions on "Capturing Images from the Net" under Resources-"step by step") need to be converted from Gif images to TIFF or PICT images (so you can use NIH software to manipulate the images). To do that you need to use GifConverter software (directions are under Resources-"step by step". Software can be found on the Tools and Download page). Remember to date the images or number them so you can open them in the proper order to view change dependent on time.
3. After the image is open click on the Hand Tool, and scroll the image toward the top of the screen so you can see the Temperature key at the bottom of the image.
4. Click on the Eyedropper Tool and go to "Windows" on the menu bar, and choose "Info". You should see X,Y coordinates and Red,Green,Blue (RGB) values. There is also an average RGB value listed at the end. Watch the values change as the eyedropper is moved over the image. The values change, depending on the color (RGB value) and the position (X,Y coordinate) of the pixel that makes up that part of the image.
5. Determine the average RGB value of ice. Put the Eyedropper Tool on the part of the key that is called ICE. Note and record the average RGB value. This is the minimum temperature for this image.
6. Click on the Hand Tool again, and move the image to the left so the highest temperature on the key is visible.
7. Click on the Eyedropper Tool again. Go to "Windows" in the menu bar and choose "Info". Move the Eyedropper Tool over the color representing the highest temperature on the key. Note and record this value. This is the maximum temperature value on this image.
8. Repeat steps 4. through 7. for several images.
NOTE : You must do this to EACH IMAGE to insure the plots you generate are to the same scale.
Make a profile plot (line graph) of the surface temperature of the ocean. Here are some tips to make things more enjoyable: a) When establishing your line of data to be plotted start in the north and go to the south. This will make interpreting the graph easier. b) Start at the same place on each image (a line of latitude in the northern hemisphere works well). c) Stop at the same place on each image as well (once again, a line of latitude in the southern hemisphere is a logical choice. d) Date the images or number them in chronological order to show change over time. To generate plot profiles from these images .
1. Open NIH image program (if open go to next step).
2. Double click on the line graph icon in the left side of the Tool Kit (just under paint bucket).
3. Select "Fixed Y axis"
4. Min=59 (pixel value for 32ºF)
5. Max=110 (pixel value for 90ºF) {these values will change for each image in this data set }.
6. Do NOT choose "Fixed Plot Size"
7. Width=300
8. Height=200
9. Profile Plot Line Width=1
10. Line Plot
11. Click so there is an "X" in the Labels box.
12. Repeat steps 1-11 for each image in this data set.
13. Go to File and choose "Print Plot".
14. You should have 5 line graphs of Sea Surface Temperature (one for each image).
NOTE: Steps 4 and 5 WILL change for each image .