#23: Blue Ice (better than Yellow Snow)

The Question

Kurt Says:
February 22nd, 2005 at 7:42 am
One the thruway there are huge rocks where they blasted to make way for the road, and on these said rocks, there is ice forming a sort of frozen waterfall, where water has seeped out of the rock. My question to you is, BA BA DUM, Why is the Ice Blue?

The Answer

Well Kurt, the answer is this: The ice is blue because the ice is blue.

No, really.

Here are the facts. Ice by its nature is tinged blue. Barely, but it’s there. The photons that enter the ice are more likely to be absorbed if they have lower energy (thus, they are at the “red” end of the spectrum). This is called “preferential absorption”. As the ice thickens, this absorption becomes more evident, and soon enough, the ice is reflecting a nice blue color.

Also, since the rocks you mention were recently blasted, there might be some manganese dissolved in the ice. This would enhance the blue color since manganese in suspension can often appear to be blue.

3 thoughts on “#23: Blue Ice (better than Yellow Snow)

  • 5/4/2005 at 1:47 pm

    Where do all of the absorbed “red end” photons go? Does the ice ever get full of photons?

  • 5/5/2005 at 8:41 pm

    The “red end” photons are absorbed by the hydrogen and oxygen atoms. Some of that photonic energy is passed on to the electrons, which become slightly more energetic in their motions. The energy goes towards transitioning the ice molecules to their next, more energetic state (water). Unlike those higher energy photons at the “blue” end of the spectrum, which jiggle their way in and around the atoms, only to bounce back out and smack you in the eye (causing you to see the blueness).

  • 5/9/2005 at 11:21 am

    I would like to reinforce the perspective that ice is not blue; rather we _perceive_ blue in the three level process of perception: 1) light rays are reflected off of an object and initiate a firing sequence in the photoreceptors of our eyes, 2) these firing sequences are combined in our brain to reflect what we’re looking at and 3) we recognize “blue”.


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