This summer in Britain has been the wettest for 100 years, with the period of April to June being the wettest ever on record. Since the devastating floods of 2007, five out of six summers have been utterly miserable. So what is responsible for this horrendous weather?
The Jet stream is an enormous ‘river’ of fast moving air, several hundred miles wide, flowing high above the clouds, at around 30,000 feet altitude. It moves East to West around the earth at 150-300 mph. The Jet stream separates the cold air in the North from the warm air in the South. Usually the Jet stream ‘meanders’ but over this summer it’s course was fixed south of the UK over Northern France, which meant that areas of low pressure from the north were being directed over Britain, bringing with them heavy cloud and rain. In contrast, the US – which is largely positioned to the south of the Jet Stream – has had a searingly hot summer with many regions affected by droughts
2. Warming of the Atlantic Ocean
So what determines the path of the jet stream? Well, the truth is that no one can completely explain this phenomenon. However, one significant factor is thought to be the warming of the Atlantic Ocean. The Atlantic naturally goes through cycles of warming and cooling (lasting 20-50 years) and it has been warming since around 1990. The warming of the water affects the surrounding air pressure, which in turn directs the jet stream.
3. Global Warming
It is believed that global warming, caused by the emission of greenhouse gasses into the earth’s atmosphere, is accelerating the warming of the Oceans. The images released by NASA of the unprecedented melt of Greenland’s Ice sheet confirm that global warming is a real threat. Studies suggest that the resulting release of heat over the Atlantic has weakened the jet stream making it more meandering. For the UK, this has brought about the terrible weather that is now becoming a staple of the British summer.