Total solar eclipse: Reading scientist to record rare data

A tracking balloon to be launched during today’s (Mon, 8 April) total solar eclipse in the US will help a University of Reading meteorologist obtain incredibly unusual atmospheric data.

Professor Giles Harrison has teamed up with Peter Gibbs (former Met Office and BBC weather forecaster and University of Reading visiting fellow) to launch the balloon, which will be released from Austin, Texas before the solar total eclipse - which is when the moon entirely covers the sun’s disc.

A specially designed and constructed instrument sensor capsule will be attached to the balloon to capture the reduction in sunlight, and any slight atmospheric motions related to the eclipse.

But this is not the balloon’s only purpose - two cameras will be attached to the system to capture a 20-second video of the moon's shadow travelling across the earth at about 1500 mph.

Professor Giles Harrison said: “A total solar eclipse is a rare and special thing – a sort of natural experiment - and I’ve tried various ways of measuring their effects since the UK solar eclipse of 1999. The national citizen science experiment for the 2015 eclipse was particularly valuable in helping understand effects on the weather-forming regions of the atmosphere. 

“In 2015 we coordinated three modified weather balloons aloft simultaneously at Reading, Lerwick and Reykjavik, which successfully measured the eclipse-induced sunlight changes by being above the clouds. At the University of Reading, we use weather balloons for all sorts of things including learning more about summertime storms, but eclipse monitoring is an unusual use.

“The next total solar eclipse will be in 2026 and only be visible in Iceland, Greenland and Spain. Hence this eclipse presented a valuable opportunity to obtain some new atmosphere data.”

Eclipse wind

In 2016, Professor Giles Harrison published a study about a total solar eclipse that occurred in May 1715. The eclipse was accompanied by a ‘strange wind’, according to astronomer Edmund Halley.

Three hundred years later, people across the UK felt this strange wind again during a partial solar eclipse. With the help of 4,500 volunteers in the National Eclipse Weather Experiment (NEWEx) meteorologists at the University of Reading were able to work out why this ‘eclipse wind’ occurred.

Speaking in 2016, Professor Harrison said: “There have been lots of theories about the eclipse wind over the years, but we think this is the most compelling explanation yet.

“As the sun disappears behind the moon the ground suddenly cools, just like at sunset. This means warm air stops rising from the ground, causing a drop in wind speed and a shift in its direction, as the slowing of the air by the Earth’s surface changes.”