Arctic Blast

Fascinating to watch the warm, moist air rising from the tops of the buildings collide with the frigid air to form what I’ll call “skyscraper snow”. The afternoon sunlight was at just the right angle, illuminating the wee, wee flakes, for me to catch sight of the phenomenon.

Neat to read a bit about how air temperature affects the size and shapes of snowflakes, too.

“skyscraper snow”
The steam from the top of the Daley Center.

Snow crystal shapes depend on temperature. From 0 to -4 degrees Celsius (32 to 25 degrees Fahrenheit), thin hexagonal plates form. Needles form from -4 to -6 degrees Celsius (25 to 21 degrees Fahrenheit), and hollow columns form at -6 to -10 degrees Celsius (21 to 14 degrees Fahrenheit). Sector plates resembling 6-petaled flowers result when temperatures are from -10 to -12 degrees Celsius (14 to 10 degrees Fahrenheit). Familiar six-armed dendrites occur from -12 to -16 degrees Celsius (10 to 3 degrees Fahrenheit). Many snow crystals can group together to form one snowflake. Most snowflakes are 1.3 cm or less in diameter (0.5 inches), but some large flakes are near 5 cm (2 inches) wide.


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