12 Mar 2014

Will it always be dreich in an independent Scotland?

As the Scots vote on independence, one aspect of the country seems to already have gone its own way – its weather. So is the notion of dull drizzle and biting blizzards myth or reality? Does Scotland really have an independent climate?

Last weekend, England and Wales were bathed in warmth and sunshine, with temperatures reaching as high as 20C. Meanwhile, Scotland was stuck under cloudy skies and temperatures around 9C.

When I tweeted a list of the warmest places on Twitter, there were some frustrated responses asking why nowhere in Scotland was included on the list. It was simply a case that none of the warmest places were in Scotland, on this occasion. 

forth_bridge_g_wp

So, is the weather in Scotland always not as good at the weather further south across the UK? I thought I’d take a look at the statistics – comparing rainfall, sunshine and temperature – to see to what extent this is true.

Rainfall

The map below from the Met Office of average annual rainfall, clearly shows a huge range in wetness – not just between Scotland and southern England, but also across Scotland.

uk_rainfall_map_MetOffice

Western Scotland has, on average, 1250-3000mm of rain each year, with the mountains having the greatest amount within this range – making it the wettest part of the UK.

This is around two to three times the 600-1000mm that southern parts of England get each year.

However, eastern parts of Scotland from the Moray Firth, through Aberdeenshire to Lothian, are actually just as dry as southern parts of England.

This is because most weather fronts arrive from the west off the Atlantic Ocean. As the air is forced up over the mountains, huge amounts of moisture are squeezed from the clouds. By the time the weather fronts reach eastern Scotland, there is little moisture left to fall – which is why it is drier.

So, in terms of rainfall, it would be true to say that the western half of Scotland is much wetter than the rest of the UK, but eastern Scotland has similar amounts of rain to southern England.

Temperature

When it comes to temperature, the difference is clear when looking at the Met Office map below, which shows the average maximum daily temperature.

uk_meanmaxtemp_map_MetOffice

The most populated parts of Scotland have an annual average maximum daily temperature of 10-13C, which is around 3C lower than the 13-15C that southern England has.

However, given the difference in latitude, this would be expected. Scotland is on the same latitude as southern Sweden and Latvia.

Scotland is in fact warmer than it should be for a place of its latitude in winter, thanks to the Gulf Stream and winds coming from a predominantly mild south westerly direction.

Sunshine

The map below, showing average annual sunshine, exhibits a similar trend to annual rainfall. This makes sense as wetter, cloudier areas are much likely to see less sunshine.

uk_sunshine_map_MetOffice

On average, southern parts of England have 1500-1600 hours (even more along the south coast) of sunshine each year, in comparison to the 900-1200 hours that much of Scotland gets.

However, eastern coasts of Scotland fare much better, with 1300-1500 hours of sunshine each year. This is due to the same effect mentioned earlier in relation to rainfall.

As weather fronts tend to be weaker over eastern Scotland with less rain, the cloud tends to break up more readily, resulting in more sunshine.

Amount of daylight

As well as the weather, there is the length of days to consider. In summer, Scotland has more hours of daylight in comparison to southern parts of the UK, due to its more northerly latitude.

So, when Scotland is bathed in warmth and sunshine in the summer, the days can seem glorious because they are longer.

However, in winter the opposite is true. Scotland has fewer hours of daylight compared to southern parts of the UK.

This, combined with the storminess of autumn and the snows of winter, can make it feel particularly gloomy.

So, whilst looking at the evidence, there are some aspects of Scotland’s weather that make it dreich in comparison to other parts of the UK. However, there is a big variation within Scotland itself, meaning that it’s not as bad as you might imagine everywhere.

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