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
Front and back However, acoustically there is little difference between a central vowel and a back vowel, with the result that the two are frequently grouped together into an even broader category of "back vowels", or a category of "non-front vowels". A back consonant includes all consonants whose place of articulation is in the soft palate (velum) or farther back, including velar, uvular, pharyngeal, and glottal consonants. From the perspective of primary places of articulation, this includes all of the laryngeal consonants and some of the dorsal consonants (specifically, excluding palatal consonants). A front consonant includes all consonants that are not back consonants,