It isn't exactly seasonal but this month's MOO Report is on snow. Due to its geographical position, Bournemouth rarely receives snow, and only a sprinkling when it does - unfortunately never enough to miss school! Nevertheless, in a wider context snow is both important and interesting to meteorologists.

The story of snow begins when super cooled water forms in the atmosphere. A requirement is that the atmospheric temperature is less than 0 degrees Celsius, the freezing point of water. The second condition is that there must be a nucleus for crystals to form around - typically these nuclei are dust particles. The size of the snow particles which form depends on a number of factors, but particularly important are water content and atmospheric temperature.

When snow falls it can be categorised by meteorologists or scientists by the amount of time it covers the ground. Most common in the UK is temporary snow cover, which lasts for just a few days at most. There are two other categories; seasonal - when areas are covered for months at a time, typically mountains in water at low latitudes like the UK or summer months in high latitudes; and additionally permanent.

Snow is both loved and hated. Whilst it can be great fun to play around in (or force days off school!) it can also be treacherous. Meteorologists are invaluable in producing information regarding snowfall on motorways, for instance. Additionally, they can often predict when avalanches will happen.

Avalanches are more likely to happen in a snowpack if the temperature on the ground rises quickly, if there is rainfall or if there is fresh snowfall. In many skiing resorts, meteorologists are employed to forecast these conditions in order to make a prediction of likeliness of avalanches. If meteorologists think there will be a dangerous avalanche, they can advise managers on evacuating the area.

MOO realises that avalanches are fascinating to many of its readers; watch out for other MOO reports about prevention of avalanches in the near future!