What Causes Snow?
When outside temperatures are low and there is moisture in the air, small ice crystals are formed. On their own they are tiny, but when they collide they stick to each other and make snowflakes. When lots of these particles join together they get heavier and once they are heavy enough they fall to the ground as snow.
Many people believe that it has to be freezing before it will start snowing, although in actual fact precipitation falls as snow when the temperatures is 2oC or below. In the UK the heaviest snow falls tends to happen when the temperature is between zero and 2oC. If the temperature is any higher than this the snow will melt as it falls and end up as sleet or rain.
Different types of snow
Snow is snow, right? Well, not exactly. There are two distinct types of snow – ‘wet’ and ‘dry’. The type of snow that falls is determined by the made up of the snow flake and how many ice crystals grouped together to form it in the first place. And this in turn is determined by the air temperature. If snowflakes fall through dry, cool air, the snowflakes don’t stick together and they tend to be small and powdery. This is the type of snow that is ideal for winter sports as it can become quite compacted under pressure. Before it compacts it is more likely to drift in windy weather.
Wet snow forms when the temperature is slightly warmer. The snowflakes melt around the edge and they just like the ice particles they stick together to confirm large heavy flakes. This type of snow is great for making snowmen and snow balls. Add a lit bit more heat and the higher temperature will melt it further, producing thick slush or sleet.
Dealing with snow
For many people (especially children!) snow is greatly desired and welcomed. For most, however, snow can be a hindrance and cause lots of travel chaos and access issues. If snow is forecast it is best to be prepared. See our other blog post on tips for preparing for winter and make sure that you don’t get caught out this winter.