Snowflakes: What’s true and what’s not?
Published: Sunday, Nov 26th 2023, 13:50
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There were considerable amounts of fresh snow in the Swiss mountains. Flakes also fell in the lowlands. But how is the white splendor actually created? And what properties do snowflakes have?
There is often something magical about the first snow in winter. The flakes are little marvels of nature. But there are also many myths about them. Which of them are true? A little knowledge quiz.
SNOWFLAKES ALWAYS HAVE SIX CORNERS
This is true if you look at their basic structures. The individual ice crystals may look like stars or needles under the microscope. However, their water molecules always sort themselves into a hexagonal honeycomb crystal lattice of water ice. It takes up more space than liquid water.
SNOWFLAKES CAN BE IDENTICAL
Not really. With a diameter of just one millimeter, a single ice crystal contains around 100 trillion water molecules. That's a number with 20 zeros. There are countless ways in which these molecules can arrange themselves. Depending on the temperature and humidity, the flake continues to form on its way to earth and takes on its unique shape.
SNOW CONSISTS OF FROZEN RAIN
That is not true. Snow forms in the clouds in the earth's atmosphere. If it is cold enough there, water vapour is deposited on so-called crystallization nuclei and freezes. Small dust particles, for example, can serve as the basis for snow crystals. They grow until they fall heavily into the depths. Whether they reach the ground as snow depends on the temperature of the layers of air they pass through.
SNOWFLAKES ARE TINY
That depends. Many ice crystals really are so tiny that they are barely visible to the naked eye. On average, a crystal visible to the human eye contains around one trillion molecules. The size of snowflakes depends on the outside temperature. From minus two degrees, smaller flakes usually fall. If it is warmer, they are larger.
SNOW IS LIGHT
That depends. One cubic meter of fresh snow weighs approximately between 50 and 100 kilograms. This is because fresh snow consists of 90 percent air. However, the structure and density of snow changes constantly depending on the temperature. Older snow can weigh as much as 400 to 500 kilograms per cubic meter. Because of these differences, you can either sink deep into the snow or walk on a solid layer of snow.
SNOW MAKES THE WORLD QUIETER
This is true for fresh snow. As it consists largely of air, it creates a labyrinthine pore space like a sponge. This absorbs sound and suppresses ambient noise. When snow crunches underfoot, it is because ice crystals break.
ARTIFICIAL FLAKES ARE LIKE NATURAL SNOW
Wrong. Snow cannons blow small drops of water into the cold air, which freeze on their way to the ground. Natural snowflakes are created by water vapor. The proportion of air in fresh artificial snow is also much smaller than in real snow.
IT ONLY SNOWS ON THE EARTH
No. In 2008, for example, the Phoenix research module found solid precipitation on Mars, according to the US space agency NASA. Researchers refer to this as snow.
©Keystone/SDA
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