NIH Image, the program used in these activities, is available for the Mac from the NIH Image WWW site.

Visible Satellite Image

This is a visible satellite image, meaning this is essentially what you would see with your eyes if you could fly 500 miles above the surface of the earth. The snow and clouds marked on the larger version of this file are bright because they reflect light back to the satellite. On the other hand, the ocean is dark because it absorbs more light than it reflects. Different types of vegetation reflect light differently and that is shown by the varying shades of grey on the land.

You could begin with geography, having the students pick out the names of different places on the image. In the absence of geopolitical boundaries, that is much harder than using a map with state and country boundaries already marked. For a starting point, try this image. A smaller version with fewer sites marked is also available.) Try Visible and Infrared Imagery for more ideas on how to use this image in the classroom.

Weather and Satellite Imagery

Students feel a real connection to the weather since it is something that affects them every day. Hurricanes and snow storms have particular appeal since they can be quite dramatic and may even result in a day off from school. The satellite imagery used for weather predictions can be found at many sites on the WWW and is often the same imagery seen on TV news programs. Try out some of our weather activities.

Viewing Phytoplankton from Space

An interesting way to start with this satellite image is to have the students figure out where the image was taken. The land has been colored black and at first it is difficult to pick out the countries surrounding the Mediteranean Ocean.

The different colors of the water depict different concentrations of phytoplankton. Red and orange areas represent the highest concentrations of phytoplankton. The scale then moves through the colors of the rainbow down to the lowest phytoplankton concentrations represented by purples and blues.

You may wish to begin with the smaller phytoplankton image since it is less overwhelming than the larger image of the north Atlantic. The color scale for this image is the same as for the previous image. The land is colored grey-brown and the black sections in the ocean are parts of the image where the satellite was unable to get enough information for a variety of reasons.

Beginning with the image from March on the left, have the students locate the highest phytoplankton concentrations. They should be able to identify higher concentrations in coastal areas and towards the Artic Circle. If the students compare the two images, they will notice that in general there is more phytoplankton in the image on the right (September of the same year).

Phytoplankton, not unlike land-based plants, cannot survive and grow without three items:

  • Sunlight
  • Nutrients, i.e. phosphorus and nitrogen
  • Carbon dioxide

There is more phytoplankton in September than March because the summer sunlight has allowed phytoplankton to bloom in the North Atlantic.

Cold water has more carbon dioxide than warm water. Water molecules move faster in warm water and the carbon dioxide (and oxygen and other gases in water) gets "bumped out" of the water into the atmosphere. Therefore, there is more phytoplankton in cold waters, i.e. near the Artic Circle.

Phytoplankton also take advantage of nutrients in runoff to bloom along coastlines. Compare the image from March with the one from September. Notice that the September image has more phytoplankton around the Amazon River. That is the end of the rainy season, hence there are more nutrients which ultimately result in more phytoplankton.

Satellite Comparisons examines seasonal changes in water temperature and phytoplankton concentration. Students also enjoy linking together a series of images to examine change over time. (step by step directions)

Sea Surface Temperature

This is a satellite image of water temperature along the east coast of the United States. The scale is as follows:

reds and oranges 24o to 28o Celsius
yellows and greens 17o to 23o Celsius
light blues 10o to 16o Celsius
dark blues 2o to 9o Celsius

The stream of warmer water that moves up the east coast of the US (as seen by water that has been colored red in this image) is called the Gulf Stream. The Gulf Stream develops in the Straits of Florida and follows the coastline until Cape Hatteras. After the cape, the Gulf Stream travels offshore and heads towards Europe. The rings that form as the Gulf Stream meanders along the coastline are called eddies.

Go to our Find Eddy activity for a classroom activity that uses this image.

Sea Ice Surrounding Antarctica

The scale for the images is as follows:

blues Open Ocean
white Ice
green Continental Antarctica

These images both depict the amount of sea ice around Antarctica. The image on the left is from March, 1990 and the image on the right is from October, 1990. Ask your students why there is more ice in October than March.

Due to the tilt of the Earth, the seasons are reversed in the southern hemisphere compared to the northern hemisphere. While October is the end of the northern hemisphere's summer, it is the end of the southern hemisphere's winter (hence the large amount of sea ice around Antarctica in October).

You can use NIH Image to measure the seasonal change in sea ice as we have outlined in this activity. Our Antarctic Ice activity has more background information and ways to use these images in the classroom.