The Formation of Snow Crystals

Team #34 From The Down To Earth School

My project is about how snow crystals form through the branching process.

The branching process creates snow crystals that most people think of when they think of snow. These crystals are called dendrites. They are a hexagonal base frozen around a dust or pollen particle with branches extending out of each of the corners of the hexagon. The branching process starts with a simple dust or pollen particle in the atmosphere, then the water molecules in a gaseous state freezes onto the particle and start forming the hexagonal base. Once the hexagon base is created the water molecules freeze onto the corners and begin to make the branches. Then the branches may have smaller branches extending out of each branch called side branches. There many types of crystals. These crystals are formed depending on mainly two variables: supersaturation and atmospheric temperature. Supersaturation is the number of grams of water molecules in one cubic meter. There can be between 0 and 3.333 * 10²² water molecules per gram per cubic meter. To form snow crystals there is between 0 and 1 * 10²³ water molecules or 0 to 0.3 grams in a cubic meter in the atmosphere. The equation used to find these numbers was solved using Avogadro's number.


My model has the branching process shown happening. There are different breeds; there is the breed waters that are the turtles representing the water molecules; there is the breed dusts in which the turtles represent the dust or pollen particle; ice is another breed that is the turtles representing ice particles; then there is also a breed for each type of crystal: plates, solid pates, dendrites, columns, hollow columns, solid prisms, and needles. The water molecules move toward the bottom of the screen or world. The dust particle moves randomly as if being blown within the wind. If the water molecules collide with the dust particle they turn into ice by changing the breed and colour. Then the ice particles move with the dust particle as if attached. The dust particle changes its shape the more ice molecules are attached. Then when the dust particle has 250 ice particles frozen to it turns into the snow crystal. Depending on the supersaturation and temperature the dust particle will turn into one of the types of snow crystals.