Walking In A Winter Wonderland…Almost

2017-09-10 17:23:05.000 – Nicole Tallman, Summit Intern

 

With the changeover to meteorological fall comes the increased possibility for snow on the summit of Mount Washington. During my time on the summit as the summer intern I was able to truly experience snow and icing only once at the very beginning of my internship. The summit seemed to be a winter wonderland with everything covered in frozen precip; whether it is ice or what was left of the blowing snow. With my experiences from that one event, I am positive that when this winter season fully comes underway I will be in awe of the beauty of the snow and ice.

 
 Figure 1. Rime and glaze ice covering the observation deck on my first week as an intern. 

Mount Washington’s winter is longer than the typical winter season. The season ranges from October to May averaging a whopping 281 inches of snowfall. With the winter season coming fast and the first few snowfalls this season underway it is the perfect time to understand the beauty behind these frozen flakes. 

The typical visualization of snow is a beautiful, lacey, symmetrical snow flake. While this may be one type of snow crystal it is not the only type that can form. Snow may fall in many different shapes and sizes depending on its unique path through a cloud. Changes in temperature and moisture will grow different shapes and sizes of snow crystals. A single cloud does not have uniform moisture or temperature within it. Therefore, the same cloud can produce differently shaped snow crystals.

 Figure 2. A chart showing different snow crystal structures and their dependence on temperature and humidity within a cloud. 

Looking at the visual above it is clear that there are a variety of shapes to snow crystals, not just the dendrite that we are all so familiar with. For example, temperatures from around 10 to 20 degrees Fahrenheit can produce needles, columns and prisms while colder temperatures from -10 to -20 degrees Fahrenheit will produce columns and plates. The moisture within the cloud will have a direct correlation to the size of the crystal; more moisture can produce larger crystals. Along with moisture there are two other ingredients needed to produce a snow crystal. Snow will form with water vapor, dust (in the form of pollen, volcanic ash or other particles in the sky), and ice crystals. These three ingredients along with the right meteorological conditions will produce snow. 

The snow typically seen on the summit of Mount Washington is produced with temperatures ranging from -10 degrees to 10 degrees Fahrenheit. This means that we see many of the familiar dendrites as well as plates.

Last winter the summit received 401 inches of snow which was 120 inches above average making it the 6th snowiest winter on record. The most significant storm that hit the summits was at the end of their winter season and fell on Mother’s day from May 14th through the 15th dumping 33 inches of snow! It was a very impressive winter (still not enough to satisfy our snow enthusiast observer, Adam)!

 
 Figure 3. A photo from the August 31st – September 1st rime and snow event. The first event of the season.
 
So far this winter season we have had two snow events. The first event lasted from August 31st– September 1st and the second was on September 8th– 9th. Both only produced traces of snowfall but that is enough to get the crew exited for winter. I may be reluctant to have the cold weather come back but I know I will enjoy the winter wonderland that comes with the snow and ice on Mount Washington.
 
 
 Figure 4. A early June sunset from my first week as an intern.

 

Nicole Tallman, Summit Intern

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