Snowflake unlikely that any two snowflakes are alike due to the estimated 10 (10 quintillion) water molecules which make up a typical snowflake, which grow at different rates and in different patterns depending on the changing temperature and humidity within the atmosphere that the snowflake falls through on its way to the ground. Snowflakes that look identical, but may vary at the molecular level, have been grown under controlled conditions. Although snowflakes are never completely symmetrical, a non-aggregated snowflake often grows so as to exhibit an approximation of six-fold radial symmetry. The symmetry gets started due to the hexagonal crystalline structure
How Do They Do It? series, presented by Robert Llewellyn. This version was released on DVD in the UK in May 2010. In the United States, the series airs on the Science Channel and is narrated by Chris Broyles. This programme is similar to the popular Canadian-produced documentary programme, "How It's Made", also broadcast on Discovery Channel networks. Episodes in the first season aired with 60-minute runtimes (including commercials). Episodes in the second season aired with 30-minute runtimes (including commercials). Episodes 60 minutes long taken the best from series 3 and 4 Each episode is 30 minutes long and airs on terrestrial UK channel five.