Defining Extreme Weather

Extreme Weather

In this course, Dr Tom Matthews (King’s College London) explores the physical processes behind and impacts of extreme weather. In the first module, we consider some definitional questions, including how weather is distinguished from climate, and how weather events are classified as “extreme”. The second module then looks at extreme temperatures, their negative effects on humans, and why hot and cold air masses form where they do. In the third module, we turn to wind extremes and the role of atmospheric pressure gradients in the weather system, and in the fourth we explore precipitation with a particular focus on its complex relationship with flood risk. The fifth module then examines different types of drought and their impacts, as well as the issue of multi-hazardous weather conditions. We conclude with a sixth module on preparation for and management of weather extremes, and the role of forecasting in this.

Defining Extreme Weather

In this module, we think about how extreme weather is defined and measured. We focus on: (i) the distinction between weather (the state of the atmosphere at a given time) and climate (the longer term statistical patterns of the weather); (ii) how weather events are defined as “extreme”, primarily through thresholds set by two factors - rarity and impact; (iii) some of the key variables which determine the characteristics of the weather, including air temperature, precipitation, and wind speed.