16 FILES Snow blowing in the wind 1 - 00:11 Snow blowing in the wind 2 - 00:16 Snow blowing in the wind 3 - 00:07 Snow blowing in the wind 4 - 00:08 Snow close up 1 - 01:00 Snow close up 2 - 01:00 Snow close up 3 - 01:00 Snow close up 4 - 01:00 Snow medium distance 1 - 01:00 Snow medium distance 2 - 01:00 Snow medium distance 3 - 01:00 Snow medium distance 4 - 01:00 Snow general 1 - 01:00 Snow general 2 - 01:00 Snow general 3 - 01:00 Snow general 4 - 01:00
A snowflake is either a single ice crystal or an aggregation of ice crystals which falls through the Earth's atmosphere as snow. Each flake nucleates around a dust particle in supersaturated air masses by attracting supercooled cloud water droplets, which freeze and accrete in crystal form. Complex shapes emerge as the flake moves through differing temperature and humidity zones in the atmosphere, such that individual snowflakes differ in detail from one another, but may be categorized in eight broad classifications and at least 80 individual variants. The main constituent shapes for ice crystals, from which combinations may occur, are needle, column, plate and rime. Snowflakes appear white in color despite being made of clear ice. This is due to diffuse reflection of the whole spectrum of light by the small crystal facets.
Chroma key compositing, or chroma keying, is a special effects / post-production technique for compositing (layering) two images or video streams together based on color hues (chroma range). The technique has been used heavily in many fields to remove a background from the subject of a photo or video – particularly the newscasting, motion picture and videogame industries. A color range in the foreground footage is made transparent, allowing separately filmed background footage or a static image to be inserted into the scene. The chroma keying technique is commonly used in video production and post-production. This technique is also referred to as color keying, colour-separation overlay (CSO; primarily by the BBC), or by various terms for specific color-related variants such as green screen, and blue screen – chroma keying can be done with backgrounds of any color that are uniform and distinct, but green and blue backgrounds are more commonly used because they differ most distinctly in hue from most human skin colors. No part of the subject being filmed or photographed may duplicate the color used as the backing.
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