Flash flooding: The physical processes involved in heavy rain

Date: Wednesday 3 October 2018

Time: 19:00 - 20:30


Inverness College
1 Inverness Campus
United Kingdom



SPEAKER | Prof Alan Blyth, University of Leeds.

ABSTRACT | Numerical weather prediction models make forecasts of the location,
timing and intensity of heavy rain showers from cumulonimbus clouds.
The models make assumptions about the physics that occur in the clouds by using parametrisations. Typically the rain develops through the sequence of the formation of cloud drops (about 1/100th mm), the growth of these drops, the formation of small ice crystals, collisions between ice crystals and supercooled cloud drops (liquid cloud drops at temperatures less than 0 deg C) to form what is called a graupel particle (like a hail particle) which falls and melts to produce a raindrop. All of this occurs in a turbulent cloud that has updraughts of about 10 - 20 m/s and downdraughts of about half as strong. It turns out that something as familiar to us as rain is quite difficult to represent
well in models. Learning more about the physical processes should lead to an improved accuracy of the forecasts. An increased warning time of even 10 mins due to an improved forecast could result in saving lives in a flash flood or severe wind gust event. In this talk, I will discuss the cloud physics processes and present examples of research that is carried out to try and better understand the processes using research aircraft and radars.

BIOGRAPHY | Alan Blyth is currently the Director of Atmospheric Physics in the
National Centre of Atmospheric Science and Professor of Atmospheric Science at the University of Leeds. began his career doing a PhD at the University of Manchester Institute of Science and Technology (UMIST), now part of the University of Manchester. He was then awarded a NERC fellowship and moved to the University of Wyoming in Laramie for 2 years. The next position was at New Mexico Institute of Mining and Technology (New Mexico Tech) in Socorro, New Mexico which was home to the Langmuir Laboratory for atmospheric physics. Alan spent 17 years at New Mexico Tech, becoming a professor and chair of the Physics Department. He then moved back to the UK in 2001 which eventually led to his current position.