Sometimes on a sunny day, freshly fallen snow may appear to sparkle, or glitter. When light hits an object, it can be:

absorbed -- in which case the object is heated,

transmitted -- in which case light, or at least some of the light, passes through the object,

reflected -- in which case it bounces back (light can also be scattered).

Reflection takes place at the boundary of the object. The reason we see many of the objects around us is because light is reflected off the object and toward our eyes. Sometimes the object only reflects, or transmits, a certain color. For example, clear water transmits all light, yet it can also act like a mirror. Think of how a calm lake can reflect an image of the surrounding trees. You can demonstrate this effect by filling a bowl, or sink, with water and looking straight down from above. Then slowly move your head to the side, increasing the angle at which you view the water surface. At a certain angle the water will begin to reflect images of objects that are around the bowl. Flat snowflakes resting on top of a blanket of snow can, like our bowl of water, act like a mirror, reflecting a portion of the sun's image toward your eye. Each 'sparkle' is an individual crystal reflecting the sun's image. Whether or not we see the sparkle depends on the angle formed between where the sun is, where we are looking and the angle at which the snowflake is resting. If all these conditions are right, occasionally as we walk by a field of snow, we'll see it glitter because of how the sun is being reflected by the different crystals of snow.