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  1. 1. Glaciers By Lauren Hendershot Click to Begin
  2. 2. Table of Contents:  What is a glacier?  How are glaciers formed?  How many glaciers are found in the world?  Why are glaciers blue?  How fast are the glaciers disappearing and why?  Photos of Glaciers…  Quiz  Answers to Quiz  References
  3. 3. How many glaciers are found in the world?  10% of land area is covered with glaciers.  Glaciers store about 75% of the land’s freshwater.  Most of the glaciers in the United States are found in Alaska!  Most of the world’s glaciers are located in polar regions like Antarctica and Greenland. Table of Contents
  4. 4. Why are glaciers blue?  Glacial ice often appears blue when it becomes very dense. Years of compression gradually make the ice denser over time, forcing out the tiny air pockets between crystals. When glacier ice becomes extremely dense, the ice absorbs all other colors in the spectrum and reflects primarily blue, which is what we can see. When glacier ice is white that usually means there are many tiny air bubbles still in the ice.
  5. 5. What is a glacier? Glaciers form where more snow falls than melts over a period of years, compacts into ice, and becomes thick enough to begin to move. That is, a snow patch becomes a glacier when its deepest layers begin to deform due to the weight of the overlying snow and ice. Alaskan Glacier Table of contents
  6. 6. How are Glaciers formed? Glaciers begin to form when snow remains in the same area year round, where enough snow accumulates to transform into ice. Each year, new layers of snow bury and compress the previous layers. This compression forces the snow to re- crystallize, forming grains similar in size and shape to grains of sugar. Gradually the grains grow larger and the air pockets between the grains get smaller, causing the snow to slowly compact and increase in density. After about two winters, the snow turns into firn – an intermediate state between snow and glacier ice. At this point, it is about half as dense as water. Over time, large ice crystals become so compressed that any air pockets between them are very tiny. In very old glacier ice, crystals can reach several inches in length. For most glaciers, this process takes over a hundred years. Aha I learned how to use hyperlinks on power point Table of Contents
  7. 7. Photos of Glaciers Gorner Glacier, Zermatt, Switzerland Antarctica Next…
  8. 8. Glaciers are disappearing due to global warming and climate change. As you can see in these two photos below the melting of this glacier over the period of only a year. This glacier changed drastically in a year. Climate change in the French Alps near Chamonix. 12 Mar 2007(left) and 12 Mar(2008) right Table of Contents
  9. 9. Scientists believe that Greenland, with its melting icecaps and disappearing glaciers, is an accurate thermometer of global warming. Photograph: Uriel Sinai/ Getty Images Table of Contents
  10. 10. 1. What is a glacier made of? 3. Where are most of the glaciers that are in the U.S. found? 2. Are all glaciers blue? 4. What percent of the land 5. Are glaciers disappearing? is covered by glaciers? To Answers
  11. 11. 1. Compressed snow 2. No, some are white. Aha not all glaciers are blue! 3. Alaska 4. 10% 5. Yes, due to climate change, global warming. How did you do? The End
  12. 12. References Page: Photos from on-line “We must do our part in Research reducing our carbon 1. NSIDC footprint if we want our children’s children to 2. WWF Blog have the opportunity to 3.Encyclopedia see glaciers in nature!” 4. USGS By Lauren Hendershot Aha there is something we can do about the melting of glaciers!