The UK - a mild spot, unconcerned about heavy snow or extreme cold because of benign currents and maritime influence around its extensive coast. Wrong! The poor population have been shuddering in winter, with lots of the white stuff and in December! Scientists have now attributed the northern hemisphere's general winter cold recently to solar activity ("sun spots"). In Nature Geoscience, these findings also predict that decadal weather itself can be predicted according to the 11 year solar cycle. For the first time, several researchers have been able to reproduce a consistent climate pattern and confirm how it works.
The link between weak westerly winds in the winter and solar activity is bolstered by the pattern's prediction of cold easterlies over the British Isles. Now with the help of measurements from NASA's Solar Radiation and Climate Experiment (SORCE) satellite, the amount of UV light reaching the earth has been revealed in detail (Previous research had to use broader spectral bands, which didn't show the solar signals properly).
A UK road during the snow in January 2010 via Shutterstock
In years of low UV activity, cold air forms about 50km high over the tropics. It is balanced by an easterly flow of air which then brings its influence to northern Europe. That means we're cold, while Canada and the Mediterranean are warmer in general. The opposite situation, at the peak of UV activity, causes strong westerlies to bring warm air and mild winters to the European continent, and Britain. Professor Joanna D. Haigh is quoted "While statistical data pointed to links between UV from the sun and winter weather, this new paper explains how those links come about."
"What we're seeing is UV levels affecting the distribution of air masses around the Atlantic basin. This causes a redistribution of heat - so while Europe and the US may be cooler, Canada and the Mediterranean will be warmer, and there is little direct impact on global temperatures," explains Sarah Ineson from the Met Office, the lead author of the report. Joanna goes on to say that there is a possibility of faulty data because they used only one NASA satellite, which is extremely honest for a weather forecaster.
The Sun, half way through it's main-sequence evolution via Shutterstock
It seems she is confident that further data will be added through the SOLCLI consortium of the National Environment Research Council. But they are confident, it seems, that seasonal forecasting has just improved immeasurably.
It's just that cloud on the horizon is worrying.