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The solar eclipse at ECN sites

On Friday 20th March 2015 a partial solar eclipse was visible across Europe, North Africa and the Middle East. Despite cloudy weather at many ECN sites, sensitive weather monitoring instruments picked up some changes.
The solar eclipse at ECN sites

Photo © Carol Taylor, JHI

The solar eclipse occurred between about 08:30 to 10:40 in the morning, peaking at around 09:30 am. Coverage across the UK was at least 83%. In the Shetland Isles, the eclipse was nearly total (97%). Observers in the Faroe Islands witnessed a total eclipse.

Most ECN Site Managers who observed the eclipse reported cloud cover, though many were able to photograph the phenomenon through veiled cloud.

We've now gathered data from several ECN Automatic Weather Stations (AWS) and other instruments. The graphs below show how the eclipse affected readings from the solarimeters (which measure incoming solar radiation), thermometers measuring air temperature (in the shade) and anemometers (recording wind speed).

Solar eclipse 20 March 2015 - Northern Ireland. Photo © Colm McKenna, AFBI
Photo © Colm McKenna, AFBI

There will not be a larger solar eclipse in the United Kingdom until 12 August 2026.

Data from ECN site Automatic Weather Stations

Measurements made every 5 minutes and averaged over the hour. The arrow marks the 10:00 am hour value, which included data taken at the peak of the eclipse, around 09:30 am.

Data shown from 7 ECN sites: CAI - Cairngorms, GLE - Glensaugh, HIL - Hilsborough, MOO - Moor House-Upper Teesdale, ROT - Rothamsted, SOU - Sourhope, WYT - Wytham
[Open map of sites in new tab or window]

We thank the following for providing these data: Chris Andrews, Bev Dodd and Sahm Amirsedghi (CEH), Helen Watson and Carol Taylor (JHI), Colm McKenna (AFBI), and Tony Scott (Rothamsted Research).

Solar eclipse 20 March 2015 - solar radiation @ ECN sites

Not surprisingly, the reduction in solar radiation (above) is clear, despite the cloud cover.

Solar eclipse 20 March 2015 - air temperature @ ECN sites

The available data also show a small decrease in air temperature at most sites (above). If you watched the eclipse yourself, or were outside at the time, you may have felt a change in temperature.

Solar eclipse 20 March 2015 - wind speed @ ECN sites

Some people have reported from previous eclipses that wind speeds may decrease during a solar eclipse. In the data we have received from sites, there is no clear change in wind speed that might be attributed to the eclipse (above). The winds at these locations were quite light before, during and after the eclipse.



Data from North Wyke Farm Platform AWS

This AWS at the North Wyke Farm Platform in Devon stores data at 15 minute intervals. These data are courtesy of Rothamsted Research (North Wyke) and were kindly provided by Deb Beaumont.

Solar eclipse 20 March 2015 - solar radiation @ North Wyke

Again, the dip in solar radiation (above) is obvious.

Solar eclipse 20 March 2015 - air temperature @ North Wyke

The temperature at North Wyke (above) decreased by about 1 Degree C during the eclipse.

Solar eclipse 20 March 2015 - wind speed @ North Wyke

There was no clear indication of a decrease in wind speed at North Wyke (above) that could be attributed to the eclipse.

Data from research tower in Alice Holt Forest

These meteorological sensors are 27m above the ground, so about 8m above the Alice Holt forest canopy in Surrey. The sensors were set to record at 5 minute intervals. These data were kindly provided by Ed Eaton and Sue Benham, Forest Research.

Solar eclipse 20 March 2015 - solar radiation @ Alice Holt

Despite thick cloud cover at Alice Holt, the solar radiation signal (above) clearly shows when the eclipse took place.

Solar eclipse 20 March 2015 - air temperature @ Alice Holt

Temperatures at Alice Holt (above) fell steadily during the night, and there is no obvious drop due to the eclipse.

Solar eclipse 20 March 2015 - relative humidity @ Alice Holt

There's no clear sign of a decrease in relative humidity (above) at Alice Holt during the eclipse.

Automatic Weather StationFurther information