LET IT... SNOW!!

What is snow? Snow flakes are not in fact frozen rain, that is called sleet. Snowflakes are the result of water vapor that condenses directly into ice. The elaborate patterns develop as the crystals grow.

A day in the life of a snowflake… In the winter the water in snow clouds are said to be “supercooled” and the water molecules begin to freeze. It is this uneven freezing conditions that brings about the diversity of snowflakes. Snowflakes begin as water vapor. This vapor comes from oceans, lakes, and even you. Yes every time you exhale you add water vapor to the atmosphere. The cooling of air causes water droplets to condense into groups forming clouds.

Types of Snow Crystals: The most basic snow crystal is a hexagonal Prism and can come in many shapes and sizes. The prism has 8 sides. 2 surfaces known as basal facets and then 6 prism facets.

How does a dull hexagonal ice crystal make such beautiful and elaborate flakes? The intricate flakes come from the condition in which the ice crystals are formed. The exact reason for why these changes occur is still some what of a mystery.  Growth depends on how the water vapor is incorperated into the growing crystals and the exact physics behind it remain unknown.   SNOWFLAKE BRANCHING

Types of Snow Flakes Simple Prisms

Stellar Plates

Sectored Plates

Stellar Dendrites

Fernlike Stellar Dendrites

Columns, needles and Capped Columns

Triangular Crystals

12 Sided Snowflake

Just to name a few…

The Changing Snow Pack… Of course we all love the beauty of snowflakes however most of our contact with snow comes after the flakes have already been destroyed after deposition. Snow has three main metamorphism processes. Destructive Metamorphism Constructive Metamorphism Melt Metamorphism

Destructive Metamorphism Is when the mechanical strength of snow is increased due to the bonding of individual ice grains.

Constructive or Temperature Gradient Metamorphism This happens after destructive phase. Here the water vapor moves upward resulting from the temperature gradient of the snow and the pores. This creates more space in the subnivean environment below the surface of the snow known as the depth hoar.

Isolative Value and the Subnivean environment Despite how it may seem snow is a relatively good insulator. It is a slow conductor of heat and a result a whole under the snow environment is present. Now it is by no means warm under there, just not as cold as it is on the surface. Many animals who are unable to store fat for insulation rely on the snow cover to keep safe and “warm” for the winter.

Melt Metamorphism The final stage of snow metamorphism is Melt. This is a some what obvious phase that occurs when ever snow is exposed to temperatures above freezing. This can also occur with rainfall

References: http://nsidc.org/snow/ http://www.its.caltech.edu/~atomic/snowcrystals/primer/primer.htm http://www.its.caltech.edu/~atomic/snowcrystals/ Marchand, Peter J. Life in the Cold Google Images