'He letteth fall the snow like wool and scatterth the frost abroad like ashes," says the author of 147th Psalm. In parts of Ireland in recent days, people might have begun to understand this aspect of the Psalms.
But in addition to moving the spirit in this way, a flurry of snow gives us the rare opportunity of examining in detail one of nature's finest masterpieces: we can observe a flake of snow.
There are billions and billions of snowflakes in the average shower of snow and no two are identical. Each one is an aggregate of hundreds of tiny ice crystals which have formed in the freezing clouds far above the ground.
The characteristic six-sided symmetry of these crystals was first spotted by the German astronomer Johannes Kepler, who described them in great detail in a pamphlet written as long ago as 1611, although the scientific explanation for their shape is of much later origin.
Snow is a more complex entity than merely frozen rain. Individual ice crystals form in the high atmosphere when water vapour freezes around tiny particles of dust or salt. The crystals grow as they drift downwards, attracting additional molecules of frozen water, almost one by one, and maintaining, for reasons which are still not fully understood, a shape whose cross-section is almost invariably a hexagon.
The commonly accepted view is that this shape can be traced to the basic molecular structure of water, which one scientist has described as "two little hydrogen atoms stuck on to a big oxygen atom, like the ears on Mickey Mouse's head". It is believed that the angle at which the hydrogen atoms protrude from the oxygen, being about 120 degrees, results in snow crystals with the familiar six-sided symmetry.
Crystals come in a wide variety of shapes and sizes. The most common is the regular hexagonal prism, with six rectangular sides and a top and bottom that are flat hexagons. Their height varies considerably; some are shallow enough to look rather like a six-sided 50p piece, while others are elongated and resemble a length from a six-sided pencil.
There are more complex forms, too. A frequent one, described as stellar, consists of a hexagonal hub with six spokes, resembling a wheel without a rim, while on the very beautiful dendritic crystal, the six spokes each have their separate branches, making it similar in shape to the traditional Christmas-card representation of a snowflake. As the crystals drift earthwards into relatively warmer air, they congregate into snowflakes, each of which may contain more than a thousand individual crystals.