What Causes Our Weather Here in the UK?

Every day we experience the weather and the effects that come with it, whether it’s the grey clouds and drizzle we so often see, or the rare occurrence of hot sun with clear blue skies. But as you become drenched in the April showers, or get thrown about in gale force winds; just take a moment to think; what is actually causing these natural phenomena’s to take place?

What Causes Our Rainfall?

Rainfall is one of the most common weather types in England, and one that I’m sure has ruined many hours of carefully perfected hair-dos, but why do we seem to get rain so much more than any other country? Well, it’s all to do with things called jet streams which criss-cross the earth at around 20,000ft above its surface and are basically narrow bands of very strong westerly winds. The UK is at just the right latitude that the polar jet stream passes right over it, and because of this, areas of low and high air pressure are formed, which in turn create similar patterns in sea pressure.

These changes in sea pressure affect the movement of winds and cause a common weather feature called depressions to form. Depressions are regions of low pressure which produces rainy and windy weather, and is the main cause of the miserable and changeable weather we so often see in the UK. Quite simply, a depression forms when a large mass of cold air meets a large mass of warm air, with the cold air usually coming from Polar Regions and the warm air from the Tropics. Heavy rain and strong winds form where these two air masses meet because the warm air rises over the cold air and condenses to form rain clouds.

How about our Snowfall?

We have explained the cause of the wet and wind that we are so used to in the UK, but how about snowfall? It may not be such a common occurrence, but still... why do we get it?

As we have already found out, the majority of the UK’s weather is determined by the polar jet stream, which brings us wet and damp weather in the form of depressions. However during winter, the oceans are normally much warmer than the land because they take longer for them to change temperature, and because of this, an area of high pressure forms above them and this interferes with our usual jet stream position.

When this newly created area of high pressure forms over the Atlantic, our usual jet-stream becomes blocked, and instead of flowing right over the UK as normal, it is actually deflected southwards slightly – allowing chilled air from the north to flood into its place – and where our usual Atlantic weather system meets the cold front from the north, snow falls. The UK was stuck like this for several weeks in 2010, which was the cause of widespread snowfall.

How About our Warm Weather?

So now all the cold, wet and windy weather is other with, how about the hot weather? This may seem like an even rarer occurrence in this country, but nevertheless it does happen.

The cause of these blissfully hot days and clear blue skies are from a weather phenomenon called anti-cyclones. These anti-cyclones are the opposite of depressions and are instead areas of high pressure where the air is constantly sinking, as opposed to rising in a depression, but why does this cause nice weather, and not bad?

Well, because this air is sinking instead of rising in an anti-cyclone, clouds aren’t formed which means that no rain can be produced, and the fact that there are no weather fronts also means that no wind can form. If an anti-cyclone was to form during the summer then would most likely bring warm weather with clear skies; while if in winter, then it would bring clear but cold days, with frosty nights. The weather will always be consistent and unchanging as long as an anti-cyclone is present.

So, there’s a quick introduction into the causes behind our country’s weather for you, and hopefully the next time you look out of your window, deciding what clothes to wear for the day and see the all-too familiar grey clouds forming above, you’ll know a little more about why it’s all happening.