With winter taking hold and snow likely to fall sometime soon, I thought that I’d use my latest science blog post to explore the science behind how the fluffy stuff is made.
So, just how is snow formed?
For snow to be created, it needs to be cold outside and there must be moisture in the atmosphere. This moisture is just like tiny ice crystals.
When ice crystals collide, they stick together in the clouds, forming snowflakes. If enough of these ice crystals stick together, they’ll become heavy enough to fall to the ground as snow.
The air temperature has to be below 2°C for it to snow, not zero degrees as often misunderstood. If it’s any warmer than this, snow will melt and fall as sleet. In the UK, the heaviest snowfall tends to fall when the air temperature is below zero and 2°C.
How big is a snowflake?
The size and make up of snow is dependent upon air temperature and the number of ice crystals that have stuck together. According to the Met Office, “Snowflakes that fall through dry, cool air will be small, powdery snowflakes that don’t stick together. This ‘dry’ snow is ideal for snow sports, but is more likely to drift in windy weather.
“When the temperature is slightly warmer than 0 °C, the snowflakes will melt around the edges and stick together to become big, heavy flakes. This creates ‘wet’ snow which sticks together easily and is good for making snow men.”
What you might not know about snow
It is possible that it can be too cold to snow. As snow is formed of frozen water, if there isn’t enough water droplets in the air then it can’t snow.
According to the Daily Telegraph, the average snowflake has a top speed of 1.7 metres per second. According to the Guinness Book of World Records, the largest snowflake on record measured 38cm wide and 20cm thick. It was observed in Montana, USA in 1887 and described by witnesses as “larger than a milk pan”.
With all this cold weather, I’ll be sure to wrap up warm on my travels with my mobile science laboratory, and I hope that you do to! I hope that you enjoyed my science blog post about how snowflakes are made, and that you have fun if it snows near you soon.