If you ever find yourself  gazing at falling snow, why not catch a few snowflakes  on your glove and examine their shapes? You might notice  that they look symmetrical, and if you look closely, you'll see they have six sides. You could say a snowflake  is simply frozen water, but compare one  with an ice cube from the freezer, and you'll realize  they're very different things. Unlike ice cubes, formed when liquid freezes into a solid, snowflakes form when water vapor turns straight into ice. But that still doesn't explain why snowflakes have six sides. To understand that, we need to delve deeper  into the physics of water. Water is made out of two hydrogen atoms and one oxygen atom. A single water molecule  thus has ten protons and ten electrons, eight from oxygen  and one from each hydrogen atom. The two electrons  from oxygen's outer shell are shared with two electrons from both hydrogens as they bond together, and the remaining  four outer shell electrons from oxygen form two pairs. We call the bonds between these atoms covalent bonds. The pairs of electrons  are all negatively charged. Similar charges repel, so they tend to stay as far away from each other as possible. The pairs form four electron clouds, two of which are where the hydrogen and oxygen share electrons. The repulsion between the unbonded pairs is even stronger than repulsion between the shared pairs, so the two hydrogens  get pushed a little further to an angle of 104.5 degrees. The water molecule as a whole is electrically neutral, but oxygen gets  a larger share of electrons, making it slightly negative and the hydrogens slightly positive. Due to its negative charge, the oxygen in one molecule is attracted to the positive charge of the hydrogen in another molecule. And so a weak bond  between the two molecules, called a hydrogen bond, is formed. When water freezes, this bonding occurs on repeat, ultimately forming a hexagonal structure due to the angle between hydrogens and oxygen within each molecule. This is the seed of a snowflake, and it retains a hexagonal shape as it grows. As the snowflake moves through the air, water vapor molecules  stick to the six sharp edges and expand the snowflake outwards, bit by bit. A snowflake's developing shape depends on atmospheric conditions, like humidity and temperature. As a snowflake falls, changes in weather conditions can affect how it grows, and even small differences in the paths two snowflakes take will differentiate their shapes. However, since conditions at the six  sharp edges of one snowflake are similar, a symmetric snowflake can grow. Weather conditions  affect snow on the ground, as well. Warmer ground temperatures produce a wetter snow that is easier to pack because liquid water molecules help snowflakes stick to each other. Melted snow also plays a critical role in another wintry activity, skiing. Completely dry snow  is very difficult to ski on because there's too much friction between the jagged snowflakes and the ski surface. So what's happening is that as skis move, they rub the surface of the snow and warm it up, creating a thin layer of water, which helps them slide along. So technically,  it's not really snow skiing, but water skiing. But it is true that  no matter how hard you look, you're almost definitely not going to find two identical snowflakes, and that's a mystery that scientists are still trying to solve, though we know that it has to do with the many possible  branching points in snowflake formation, and the differences  in temperature and humidity, and while we wait for the answer, we can enjoy watching these tiny fractals falling from the sky.