Snow

Snowflake Symmetry


The vast majority of snowflakes do not display the perfect six-fold symmetry we expect. According to Kenneth G. Libbrecht, Professor of Physics and snowflake researcher at Caltech, snowflakes come in all sorts of shapes, some with six- fold symmetry, some 12-fold, others are hollow columns, needles, triangles, and, most commonly of all, irregular lumps. He’s written The Field Guide to Snowflakes to help collectors identify all the different types. Working in Southern California, his own snowflake collection must have taken quite some time to put together.

The source of the misapprehension is that micro-photographers seek out symmetrical snowflakes as their subject matter, sifting through thousands to find one suitable one. The resulting images are then aped by schoolchildren - the ease of cutting symmetrical shapes with scissors appeals to them and to their teachers – and so we all grow up believing in hexagonal snowflakes.
 

Emergency Snow


If there’s no snowfall this Christmas, and you’ve forgotten to buy any of the artificial kind, there are a couple of ways to improvise. You can use detergent powder and a little water or, in a pinch, extract the stuffing from nappies.
 
Disposable nappies contain a super-absorbent chemical called sodium polyacrylate which can absorb as much as 200 to 300 times its mass in water. When sodium polyacrylate is exposed to water, the higher concentration of water outside the polymer than inside draws the water into the centre of the molecule via osmosis. Sodium polyacrylate will continue to absorb water until there is an equal concentration of water inside and outside the polymer. The same chemical is used in the nappies worn by astronauts - known as 'maximum absorbency garments' which are worn during lift-off, landing and extra-vehicular activities.
 

Dreaming Of A White Christmas?


If we take London as our reference point and define a white Christmas as one where there is snow lying on the ground (as opposed to the usual bookies' definition of a flake of snow falling on Christmas Day, whether or not it lies) then there were only four during the 20th century: 1927, 1938, 1970, and 1981 (a year which the bookies wouldn’t have counted because it didn't actually snow on 25th Dec - but there was snow on the ground).
 
There happened to be snow every Christmas of the first eight years of Charles Dickens' life, which probably explains why white Christmases are a consistent feature of his stories. His snowy childhood has its origins in the colder climate of the period 1550-1850 when Britain was in the grip of a 'Little Ice Age'. Winters were particularly persistent and severe - 1813-14 was the last winter that a 'frost fair' was held on the frozen River Thames in London. Before the change of calendar in 1752, which effectively brought Christmas day back by 12 days, snow was even more likely as Christmas comes at the beginning of the season for snow. Wintry weather is more likely in January.
 
Our last white Christmas was in 2010 when there was snow on the ground at 83% of stations - the highest amount ever recorded - but snow or sleet also fell at 19% of stations. Climate change has brought higher average temperatures over land and sea (which reduces the chances of a white Christmas) but the natural variability of the weather will not stop cold, snowy winters happening in the future. 

New York gets 15 times as much snow as the South Pole.

A snowflake that falls on a glacier in central Greenland can take 200,000 years
to reach the sea.

VOLTAIRE (1694-1778)

No snowflake in an avalanche ever feels responsible.

The only specialist cider shop in Bristol is located on 'Christmas Steps' and run by a 'Mr Snowman'.

The only specialist cider shop in Bristol is located on 'Christmas Steps' and run by a 'Mr Snowman'.

Iceland was called 'Snowland' before the present name caught on.

ROBERT SOUTHEY (1774-1843)

Their wintery garment of unsullied snow
The mountains have put on

Ernest Shackleton took cocaine with him to the Antarctic to combat snow blindness.

The world's heaviest snowfall in a 24-hour period is 190 cm on April 15, 1921 in Silver Lake, Colorado.

VLADIMIR NABOKOV (1899-1977)

Genius is an African who dreams up snow.