Think of a Jet stream as a fast-moving river of air. It is generally defined by wind speeds of 50 knots or greater with the strongest wind contained in the core of the jet stream. They form along boundaries between hot and cold air. Since these hot and cold air boundaries are most pronounced in winter, jet streams are the strongest and farther south during the winter. That also means jet streams are weaker and farther north in the summertime. Troughs will most likely have clear air turbulence as

25K views · 200 reactions | The Jetstream is currently weak and split, lying to both the north and south of the UK. However, it is set to strengthen into a single jet over the next few days and lie across the UK. This change will bring more unsettled weather for all as we head into the weekend, but it will be less cold as a result. | Met Office | Facebook

Here's a look at how the jet stream will play a pivotal role in the weather we can expect this week | Met Office