Glacier
A glacier is a large body of ice and snow. A glacier forms because in a particular spot, the snow does not all melt in summer. Each winter more snow is added, and the weight of all the snow creates pressure that turns the lower parts into ice. After many years of this happening, the glacier will start growing very big. It becomes so heavy that gravity makes the ice flow downwards like water, just much more slowly - only about 50 metres (164.04 feet) per year. New snowfalls replace the parts that flow away.[1][2]
Glaciers will only form in places that are cold enough and get enough snow over time. This can take a long time, normally hundreds or thousands of years. There are two kinds of glaciers: continental glaciers and alpine, or mountain, glaciers.
Continental glaciers are glaciers that spread out over a lot of land. They showed up mostly during the Ice Ages a long time ago, but there are still some continental glaciers in Greenland and Antarctica. They often flow downwards into the sea, where they break up. The broken parts that float in the sea are called icebergs.
Alpine glaciers are smaller than continental glaciers and form in mountain areas. They usually flow down until they reach a point where it's so warm that the ice melts completely during the summer.
Glaciers are very important because they affect the environment a lot. They do this because they are very big and heavy, so they erode mountains and land when they move and scratch the rock they sit on. Also, since they froze long ago, snow crystals and air bubbles inside are kept in good condition for scientists to look at. Nowadays, glaciers have been melting more than they used to because the climate is changing and global warming is happening[source?].[3]
Glaciers are the largest deposits of fresh water on Earth. The largest bodies of salt water are the oceans.
Glaciers appear blue in color because water (including the frozen water that makes up glaciers) is very good at absorbing light. Only the strongest light with the most energy is able to escape. Blue is the color of light that has the most energy, so blue is the only color of light that can escape without being absorbed. The thicker the glacier is, the more blue it appears.
[change] Other websites
- Swisseduc - Glaciers online Website on Glaciers in English and German
- Time lapse movies of Grosser Aletschgletscher
- Illustrated glossary on Glaciers online, in English and German
- Glacier information for schools
- National Snow and Ice Data Center - Glaciers
- USGS Glacier Studies Project
- Glaciers and Glacial Hazards - USGS
- 2003-08-15 Scientists Rewrite Laws Of Glacial Erosion
- Fjords National Park, Alaska
- NOVA scienceNOW - A 7 minute video of the NOVA broadcast of July 26, 2005. Hosted by Robert Krulwich, the video is about the world's fastest glacier and why it is moving too fast.
[change] References
- ↑ Hambrey, Michael; Alean, Jürg (2004). Glaciers (2nd ed. ed.). Cambridge University Press. ISBN 0-521-82808-2. OCLC 54371738.
- ↑ Benn, Douglas I.; Evans, David J.A. (1999). Glaciers and glaciation. Arnold. ISBN 0470236515. OCLC 38329570.
- ↑ * Bennett, M.R.; Glasser N.F. (1996). Glacial geology: ice sheets and landforms. John Wiley & Sons. ISBN 0471963445. OCLC 37536152 33359888 37536152.
[change] Uncited references
- Walley, Robert (1992). Introduction to physical geography. Wm. C. Brown.
