There was a few inches of snow today in Amersham. I didn’t venture out on wheels. Instead we went for a walk. A good number of people had come out. Some cars skidded by to hug the trees on the roadsides. A gentleman pulling his young daughter on a red plastic sled. A tiny puppy rushed to them, wagging its tail vigorously in excitement. I think it wanted to pee on the gentleman’s wellies. We – the wife and I – made a snowball and rolled it along with us. I quickly learnt the lesson: a rolling snow ball gathers lot of flakes. That reminds me. Is it “a rolling stone gathers no moss” – the saying? Never understood its point. It confuses me. Is it good or bad, the moss gathering?
In the backyard we made a sculpture of Snow White: carrot nose and plum eyes. No lungs, liver or heart. Its just snow all inside. You see her above wearing a fetching hat.
Pause. This being a science blog and me being the silly sod who writes here, I must fess-up. When I started writing this post, I really was thinking of two questions: Why does snow stick together and allow us to ball it up? Why is it white?
I got carried away by a momentary literary ambition at the beginning. Back on the ground now. There’s snow and it’s white. Its white for the same reason that your towel is white (yes, your white towel that is now a light shade of brown. I am speaking of it when it was new). The towel is white because it reflects all the visible colors evenly. It absorbs some but when it reflects it is democratic. No color is given preferential treatment. If you hadn’t paid attention in school, a mixture of all visible colors is another color: White.
Snow is like a towel made of ice crystals – very tiny ice crystals. Ice is not a reflector so how these ice crystals turn light white is not exactly how a towel turns light white. When light enters ice, it bends and exits the crystal only to enter another crystal and bend again. After running here and there and undergoing ambushes all around, part of the light that entered escapes and runs for life. Of course, light that escaped may still be unlucky. We may place our nasty eyeballs in its way and swallow it completely. So, then snow reflects light democratically – that is, reflects light of all colors evenly. That as we noted before is called white light. Alright. What was the other question? Snowballs. Yes.
Snow can be balled up only if it is not powdery. Moisture is essential for making a snow ball which means in regions where the temperature is well below zero, you cannot make snowballs. A good explanation of this is here.
My sincere apologies to Snow White for the nose and the absence of dwarfs – and her ears. When it snows again I promise to have the dwarfs and a pair of ears ready.