Is Scotland's weather getting worse?
Scotland's weather - love to talk about it, love to moan about it - will we ever get used to it? And is it really getting worse? We can all remember hot, sunny summer days when we were kids, playing outside for hours in the baking heat. But is this a true representation?
Weather presenter Stav Danaos gives us the lowdown on where our weather comes from and what's really been happening during summer through the decades.
The Scottish Summer
Weatherman Stav Danaos looks back through weather statistics to see if summer 2011 is really worse than others. He explains the weather patterns that bring an ideal summer or a wet washout. BBC World Affairs Correspondent Allan Little describes some of the key moments from his career and answer questions about what it is like to report the world in an age of conflict. Bill Boyd reads his poem Hogmanay, written in the style of Robert Burns.
Where does our weather come from?
As we can all testify, UK weather is very changeable. Due to our island group's position at the edge of the Atlantic, close to the Arctic and next to the European continent, we experience the effects of a variety of air masses, as shown in the map below. Moist maritime air flows in from the west, bringing milder, wetter weather. The cold Arctic air comes from the north, while warm, tropical winds come in from the south. The air coming from continental Europe tends to bring dry, hot conditions in summer but cold, dry weather during the winter.
This creates variable weather that changes from day to day between different regions and within different regions. Consequently, predictions or forecasts can be difficult and we often see the weather changing daily. For example, it is not uncommon to see a run of two or three hot and sunny days during summer, followed by several days of lower temperatures and rain.
The east/west divide
The weather in Scotland largely falls into an east/west split and this is down to the shape of the landscape. When prevailing winds from the west bring moist air, the mountains of the Highlands and Southern Uplands force the air upwards. The air rises and cools, forming rain clouds. By the time the air has passed over the mountains, much of its moisture has been lost. A rain shadow is created, bringing drier weather to much of eastern Scotland. As a result, Edinburgh receives only about half the rainfall of Glasgow. Further north the difference is more dramatic: Aberdeen's rainfall is about a third of what Fort William or Skye experience.
The wind is largely responsible for this localisation of weather in Scotland. If there is no wind, you will generally find that the conditions are the same across the country as the shelter of the mountains has no effect.
This variable climate gives rise to some interesting findings, such as:
Are our summers getting worse?
If we define 'worse' as lower temperatures and more rain, then the answer is "no". The evidence actually suggests that temperatures have risen, and rainfall has decreased since 1914. So, in that sense, the summers are improving. The amount of sunshine that Scotland enjoys on average has stayed the same. The overall message is that our climate is changeable. Scotland experiences a mixture of dry and wet weather during the summer which can vary across the country. Check the weather report before you go out and pack those waterproofs just in case!