The document discusses glaciers, including what they are made of, how they are formed, where they are located globally, why some are blue, and how quickly they are disappearing due to climate change. It provides photos of glaciers and a short quiz about glaciers. In summary, the document serves as an introductory overview of glaciers that covers their composition, formation process, global distribution, color variation, and threats from climate change impacts.
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. 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. 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. 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. 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
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. 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. 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. 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. References Page:
Photos from on-line “We must do our part in Research
www.wikimedia.org reducing our carbon 1. NSIDC
footprint if we want our
www.guardian.co.uk 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!
