Stories from the Barn
A hive of activity in the Hampshire downlands
Icicles and Frosts Winter’s Jewels
The magic of icicles and frosts, sparkling jewels of Winter.
Advent Calendar 11
Waking up to a sunny Winter morning sparkling with icicles and frost are nature’s gifts to us when the days seem short and dark.
Rows of icicles hanging suspended like tubular bells show off the simple artistry of nature. They stay with us for a limited time but long enough to observe that not all icicles are the same. If you look at them carefully they are made up of ripples along their lengths. If you measured these ripples you would discover the astonishing fact that they have the same wavelength, that is the distance from peak to peak is the same. These ripples come about because of the salt content of the water.
How do icicles form?
For an icicle to form it has to be a very cold day with the temperature falling to well below freezing and ice and snow in the mix. The sun then needs to come out and impart some energy so that it melts some of the ice and snow. The water droplet that is formed then runs down the roof or branch but freezes as it loses heat to the colder air. The next drop does the same and so on forming a tubular shape. The icicle continues to form as the water runs down the structure adding a thin film as it goes.
This thin film of water gives off heat to the air around it by the process of conduction. As warm air rises, it removes heat from the liquid layer and so freezing continues. The shape of the icicle, an upside down cone, is determined by this wrap of warm air. More heat escapes from the tip where it is thinner. The base of the icicle is thicker and grows more slowly, the tip grows faster and so we get a pointed icicle.
What is frost?
At its simplest, frost forms when water vapour comes into contact with a surface whose temperature is below freezing. However there are several different types of frost and who better than to explain the differences than the Met Office.
Who is Jack Frost?
Jack Frost is a way of personifying the deep icy cold of Winter. It is believed to come from stories from Nordic lands where the grip of an icy Winter needs to be controlled for reindeer to thrive. Ice men and women, legendary figures who controlled the ice and snow can be found in many cultures.
Read a good book that will chill you to your core.
Black are my steps on silver sod;
Thick blows my frosty breath abroad;
And tree and house, and hill and lake,
Are frosted like a wedding cake.‘
~Robert Louis Stevenson, ‘Winter Time’