Solar Eclipse and Weather Patterns

Tuesday 03rd Mar 2015 by theWeather Club

Solar eclipses have a local and regional impact on weather patterns.  During the near-midday solar eclipse on 11th August 1999 a co-ordinated investigation into the weather conditions was undertaken. The study explored the influence on meteorological parameters including air temperature, wind, radiation and clouds, and the data was compared to a weather forecast model to predict what would have happened without the eclipse.  

The real-world experiment revealed a clear and widespread dip in the daily temperature profile at various stations across the UK as the Earth was deprived of sunlight. This drop was typically around 1oC, although some larger temperature drops were measured locally in south-east England and East Anglia where skies were clear. 

Wind speeds also dropped on average 0.7 m/s and the wind direction turned anticlockwise becoming more easterly, agreeing with an ‘eclipse cyclone’ hypothesis that was proposed in 1901 by H Helm Clayton, one of the first scientists to investigate the impact of an eclipse on weather. He suggested that when the shadow of the moon is cast on Earth, a core of cold air develops, around which a weak, short-lived cyclone forms, skewing the winds anticlockwise.  

There were also reports that low-level, convective cumulus cloud dispersed during and immediately following mid-eclipse.

2015 Solar Eclipse Weather Experiment

On Friday 20th March a total solar eclipse will occur across the far Northern regions of Europe and the Arctic. This will be the last total solar eclipse in Europe for over a decade - the next one will be on 12th August 2026. For more information visit: http://www.solareclipse2015.org.uk

University of Reading and BBC learning are joining forces and inviting schools and members of the public with weather stations to participate in a live research project.

The aim is for participants to provide weather observations during the solar eclipse from around the UK, to assist the Department of Meteorology in Reading to use the eclipse as a natural experiment on the weather.

Participants will be asked to make frequent observations of temperature, wind, and cloud during the morning of the eclipse.  The University of Reading are also planning to launch weather balloons with UV sensors attached.

Data from the experiment will be displayed at the Stargazing Live Event, to be held in Leicester. The BBC Stargazing Live programme will link to this event and may feature the experiment. It is unlikely that participants will be mentioned by name

If you would like to take part, please email stargazing.schools@bbc.co.uk to register your interest.