Snowflake of ice. At that stage, the snowflake has the shape of a minute hexagon. The six "arms" of the snowflake, or dendrites, then grow independently from each of the corners of the hexagon, while either side of each arm grows independently. The microenvironment in which the snowflake grows changes dynamically as the snowflake falls through the cloud and tiny changes in temperature and humidity affect the way in which water molecules attach to the snowflake. Since the micro-environment (and its changes) are very nearly identical around the snowflake, each arm tends to grow in nearly the same way. However, being
Front and back Front and back From an articulatory perspective, phonemes can be described as front or back. Front vowels refer to vowels articulated towards the front of the mouth. This can either refer to vowels that are more front than central or, more rarely, only to fully front vowels, i.e. the ones that are articulated as far forward as possible in the mouth. A similar distinction holds for back vowels, which can refer to vowels that are more back than central or, more rarely, only to fully back vowels, i.e. the ones that are articulated as back as possible in the mouth.