Summer rain mystery to be investigated with balloon squadron

Cloud experts and students from Reading will launch a squadron of balloons to help solve one of the biggest weather problems the UK faces - accurately forecasting sudden rain showers. 

The issue has troubled meteorologists for years but a new £2.7 million project funded by the Met Office and Natural Environment Research Council aims to put an end to this prediction problem. 

Scientists at the University of Reading will focus on improving forecasts for spontaneous summer showers and thunderstorms, and working out why sometimes big clouds do not mean heavy rain and why at other times rain appears with little warning. 

Thorwald Stein, an Associate Professor from the Department of Meteorology at the University of Reading will lead the research at Reading in the WOEST (WesCon - Observing the Evolving Structures of Turbulence) project. He said: “We know from previous British summers that heavy rain can sometimes appear unexpectedly, so our goal is to predict the unpredictable. 

“Forecast uncertainty is not only annoying for planning your day, but it also has big impacts on the economy and society. Heavy rain and thunderstorms means events are cancelled or postponed, transport is impacted and lives are put at risk.  

“We want to improve our forecasts to make sure people are safe and are able to go about their everyday lives.”

Mixing methods

The University of Reading is one of five institutions taking part in the £11 million scheme, which will focus on improving the understanding of air and cloud movements caused by fluctuations in wind, temperature and humidity.

Their projects will link with the Met Office’s Wessex Convection Experiment (WesCon), which will collect observations of summer convection, a process that drives cloud formation and can produce heavy rainfall and thunderstorms. Reading’s scientists will be remotely operating the world’s largest steerable meteorological radar based at Chilbolton to track and scan storms in real time, and guiding research aircraft to target the most promising clouds for measurements.

Yet in a project using sophisticated airborne laboratories and state-of-the art radars, the humble weather balloon will still play a vital role. Staff and student volunteers will be launching eight radiosondes (also known as weather balloons) per day at 15 times during the summer. The balloons are filled with helium and very stretchy and are designed to travel very high into the stratosphere. As they go higher, they expand. They are used to obtain vertical profiles of wind, temperature, and humidity. This information will help researchers understand how clouds grow to greater heights and produce heavier rainfall