winter

Winter is coming

The maps above show the UK winter (Dec, Jan, Feb) averages for 1981-2010. The analyses are based on 1 km grid-point data sets which are derived from station data (Source: Met Office)

As we approach the winter season and temperatures start to dip, we take a look at winter weather in the UK – what affects it, seasonal extremes, what an ‘average’ winter looks like and link to some ‘wintry’ articles of interest.

Dreaming of a white Christmas? 2017

As we head closer to December, one of the questions we are often asked as meteorologists is “Will it be a white Christmas?” The first thing to clarify, is what exactly is being asked – do you want to know if anywhere in the UK will see a single snow flake or are you envisaging streets and roofs with a dusting of the white stuff when you wake up on 25 December. 

Weather Facts for Winter 2017 issue theWeather Club Mon, 18/12/2017 - 10:14

1) 30% of solar energy is reflected back into space by clouds, snow, ice etc

greenland ice sheet

 

2) The diameter of a lightning channel is 1 -2 inches

How does hoar frost form?

Under clear, cold nights in winter, a hoar frost can form.

Hoar frost forms when water vapour in the air comes into contact with an object that is below freezing. Rather than the water vapour first condensing onto the object and then freezing, the water vapour immediately freezes to form ice crystals. The hoar frost is distinctive due to its feathery structure and the freezing process is so quick that it traps air, giving it a white or silver opaque appearance.

What causes these beautiful frost patterns?

Clear nights and plunging temperatures can deposit a thick frost by daybreak. For frost to form, the temperature of the surface must be below 0°C. But what causes these pretty, leaf-like patterns? The patterns are the result of very tiny imperfections on the glass, such as scratches, specks of dust and salt, or the residue from washer fluid. These variations in the surface affect the way that the ice crystals form and branch out, forming the beautiful patterns captured in this image, taken in North Yorkshire on an smartphone by Paula Davies.