A large-scale weather phenomenon associated with low pressure and cloudy, wet and windy conditions.
The strict meteorological definition of a storm is a wind measuring 10 or higher on the Beaufort scale (meaning a wind speed 55 mph) or more, however popular usage is not so restrictive.
In the UK, storms are often linked to frontal systems associated with depressions. In a depression (also called mid-latitude cyclones), air rises and cools, and water vapour condenses to form clouds and perhaps precipitation. Consequently, the weather in a depression is often cloudy, wet and windy, with winds blowing in an anticlockwise direction around the depression.
Low pressure systems track across the Atlantic every few days and dominate the weather over Europe. They sometimes bring with them high winds or heavy rainfall that can cause flooding. These low pressure systems tend to follow similar paths across the Atlantic, along what is known as the North Atlantic storm track.
Find out more
- UKCP09 provides a commentary about potential future changes in storms over the UK. For an overview, go to section 5.9 of the Briefing report, with further details in Annex 6 of the UKCP09 climate change projections report and section 2.3 of the UKCP09 Marine & Coastal Projections report.
- A discussion on how well HadRM3 (the regional climate model, RCM, used in UKCP09) simulates large-scale atmospheric features is presented in Annex 3.4.2 of the Climate change projections report.
- Recent trends in storminess are described in section 1.6 of the Observed Trends report. This uses observed sudden changes in mean sea level pressure to characterise a storm event.