What’s to know about snow?
I AM over this hot, dry weather so this week I am going to talk about snow. I was lucky enough a couple of years ago to go on a snow chase into northern NSW and wow, what an experience.
So, how does snow form and what's the difference between snow and hail?
Snow needs the right temperature to form. The atmosphere needs to be cold, but not freezing and there needs to be moisture. The moisture needs to form into tiny ice crystals and when these crystals collide they stick to each other and form snowflakes. The moisture has to be in a vapour form for the minute crystals to form. Any heavier and the droplets will form either hail or rain. If enough of these crystals join they will fall to the ground as snow.
The optimum temperature for snow to form is between minus-1 and plus-2 degrees, although it can form at temperatures above and below this in certain conditions. To use England as an example, the heaviest falls recorded are between these temperatures. If the snow strikes warmer air as it falls it may melt and fall as sleet (slushy rain), rain, hail or graupel (very tiny hail). The snow itself can keep the air temperature cool as it melts by cooling the surrounding air and it may reform into "wet snow" if this happens.
So, what is wet snow and dry snow?
Snowflakes are made up of ice crystals. These crystals group together and the size of the flake is determined by the temperature and humidity. If the humidity is low and the air is 0 degrees or below the flakes will be small and powdery. They do not stick together and this dry snow is what our Winter Olympic athletes are looking for in Russia. This snow is what will blow in flurries and drift in winds. If the temperature is around 1 degree the snow will form large, clumped crystals and the edges will melt and stick together. This is the big, heavy and sticky flakes that are perfect to make snowmen but no good for snow boarding!
Snowflakes can form as stars, prisms and hexagonal plates with every flake being unique. Even though every flake is an individual they always have six sides.