It's January: what better time to think deep thoughts about ice? The word _cryosphere_ refers to the frozen parts of the planet, including sea ice, glaciers, and frozen ground. The National Snow and Ice Data Center has an "entire web site":http://www.nsidc.org/cryosphere/ devoted to things cryospheric - and you could spend a good chunk of time getting lost in the depths of icy information.

Why are icebergs blue? How does sea ice form and melt? How does precipitation affect glaciers? What determines weather in the Arctic? Why is there a hole in the ozone layer over the South Pole? Answers to these and dozens more questions can be found at "The Cryosphere: Where the World Is Frozen," NSIDC's comprehensive online field guide to Earth's ice. Learn about an "upcoming expedition":http://nsidc.org/icetrek/ in which six scientists will travel via helicopter to an iceberg floating near the Antarctic Peninsula, where they will install snow sensors, weather instruments, and other equipment to measure the life cycle of the iceberg as it travels through the water toward the warmer climate of the South Atlantic. The researchers hope this project will help shed light on how melting icebergs, due to climate change, will impact sea levels. Image credit: "NSIDC":http://nsidc.org/