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Snow Crystal Science – The Art and Physics of Colorado Snowflakes

Colorado is best known for its snow-capped peaks and ski resorts. This makes snow and the formation of snowflakes one of the most important and interesting topics in the wintertime here in the Centennial State. Snowflakes can vary depending on many different physical characteristics in the atmosphere, which can determine the type of powder that a skier would experience on the slopes as well as on the roads.

Snowflake Formation:

How do snowflakes form? Humidity and temperature are the most important factors when it comes to snowflake development. The life of a snowflake starts as a very cold water droplet that attaches itself by means of freezing to an ice nuclei such as pollen or dust. This starts the hexagonal ice particle that will eventually evolve as it falls through the atmosphere. The processes of facet formation and branch development are responsible for creating the iconic shape of a snowflake. No two snowflakes are the same, due to the varying atmospheric conditions at each stage.

Microscale Dynamics:

While a snowflake falls it encounters many different physical nuances that change how it is shaped. Conditions such as varying temperatures, humidity, and different ice nuclei as well as the timing and order of these conditions can create an infinite amount of snowflake shapes. This is why no two snowflakes are the same.

Snow Crystal vs. Snowflake:

Snowflakes are slightly different from snow crystals in that they are often used as an umbrella term for many different types of winter precipitation. This could include one snow crystal or a group that collide into each other resulting in larger flakes. Snow crystals on the other hand result from water vapor skipping the liquid phase and turning directly into ice.

Types of Snow Crystals:

  • Hoarfrost: Ice crystals deposited on surfaces below the frost point, directly transitioning from vapor to solid.
  • Rime Frost: Formed when supercooled droplets freeze and attach onto exposed surfaces, often arising from freezing fog or mist droplets.
  • Graupel: Rounded, opaque pellets formed as ice crystals fall through supercooled cloud droplets, distinct from hail with a softer, crumbly texture.
  • Polycrystals: Snowflakes composed of numerous individual ice crystals.

Controlling Powder Type for Skiing:

The type of powder that a skier or snowboarder would experience depends on the size and shape of the snowflakes. The lightest or “fluffiest” powder is typically created when larger snowflakes fall. These can vary in shape to form larger dendrites, sectored plates, or thin plates. These form when the moisture content is higher with colder temperatures.

Temperature and Moisture:

Warmer temperatures between 26 and 32 degrees Fahrenheit, can create heavier snow flakes taking the shape of small dendrites and plates [Fig. 1]. Temperatures between 0 and 14 degrees Fahrenheit can create needle shapes and with more moisture, can create solid prism shapes. On the other hand, very cold temperatures between -6 to -31 degrees Fahrenheit can provide smaller columns and plates due to the lack of moisture.

Figure 1 – “Microscopic view of snowflakes by Wilson Bentley. From the Annual Summary of the Monthly Weather Review for 1902. Bentley was a farmer whose hobby was photographing snow flakes. Source: NOAA Photo Library archives Weather Wonders collection, (Image credit: NOAA)” (NWS)

Perfect Conditions for Blower Powder:

The term “blower” powder is often used for the ideal type of snow for skiing and snowboarding. The snowflakes that are responsible for this type of powder typically form in the temperature range of of 0 to 10 degrees Fahrenheit. Large dendrites form and begin to stack amongst and on top of each other, forming air pockets. These air pockets give the snow a “bouncy” quality and is ideal for snow sports.

The next time that you hit the slopes of the Colorado Rockies, take a look at the incredibly intricate snowflake patterns that have fallen. Colorado is rich in nature’s wonders and continues to amaze everyone who gets to experience its beauty.