How is ice a black body/almost a back body?

[R Power]

I read somewhere that ice and snow are almost black bodies but the reason wasn't given.
But how can it be? Ice appears white...so it reflects most light incident on it, then how it can be even almost a black body? <:|

 

[Andy Resnick]

Snow is (nearly) perfectly absorptive in the infrared.

http://www.civil.utah.edu/~cv5450/Remote/AVIRIS/optics.html

So at near infrared wavelengths (call it 1-3 microns) snow acts like a blackbody. Not sure about the MWIR (3-5 microns) and LWIR (8-12 microns) wavebands.

 

[R Power]

thnx

 

[thopsy]

You are right! A black body must, in theory, appear black to the eye. If the radiation of interest is limited to a particular range, say infrared, then the surface could be said to behave like a blackbody in this band. But strictly speaking, a blackbody has an absorptivity and emissivity of 1, and a reflectivity of 0 for all electromagnetic radiation.