Do the British have weather worth talking about?

NASA Earth Observatory images by Joshua Stevens, using VIIRS and MODIS data from LANCE/EOSDIS Rapid Response and the Level 1 and Atmospheres Active Distribution System (LAADS) and Land Atmosphere Near real-time Capability for EOS (LANCE), and Landsat data from the U.S. Geological Survey.

Everyone knows the British like to talk about the weather. But last week even NASA was talking about the British weather – so you know something must be happening!

Well, it’s been hot. Now I know many readers from other parts of the world will be wondering what all the fuss is about. But for the UK, things have been hot!

According to the UK Meteorological Office (Met Office), June was an exceptional month which included some climatic records. The key highlights were:

  • Warmest June on record for Wales and Northern Ireland, with the highest temperature of the month was 33.0 degrees centigrade recorded in Wales at Porthmadog, Gwynedd.
  • A provisional national high-temperature record for Scotland of 33.2 degrees centigrade at Motherwell on 28th June (although there is a subsequent concern about the accuracy of this reading).
  • UK mean temperature was 14.8 degrees centigrade, provisionally making it the third warmest June since 1910.
  • Sunshine was a whopping 42% above average – provisionally making it the fifth sunniest June since 1929.
  • Rainfall was less than half normal average, with parts of England and Wales receiving less than 10% of average rainfall with some places receiving less than 2 mm.
  • The Met Office issued its first-ever thunderstorm warning.

This is a heatwave for us! The last UK heatwaves were in August 2003 and July 2006, and so you can see this is not a hugely frequent event!

What does all this have to do with NASA?

Last week they issued the image at the top of the blog which showed an almost cloud-free United Kingdom – there were a few wisps of cloud over the South West, Scotland and Northern Ireland. The image was acquired on the 27th June using a composite of scenes acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite and the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite. This image was obviously such an unusual event, that they decided to write a short article about it too!

So is this event really this rare?

Armitage et al. 2013, published the paper ‘Probability of cloud-free observation conditions across Great Britain estimated using MODIS cloud mask in Volume 4 of Remote Sensing Letters. Using MODIS data for 2005 their research predicted that the probability of cloud-free skies on any given day over Great Britain is only 21.3%. Somewhat surprisingly the maximum probability of 33.3% is in November, and the minimum probability of 12.9% is in March. This compares to the rest of the planet which has a 33% probability of cloud-free skies on any given day, whilst the oceans just have a 10% probability of being completely cloud-free.

Top of atmosphere colour composite created from SeaWIFS data acquired on 18th May 1998. Data courtesy of NASA.

In our experience, cloud-free images of the UK are very infrequent! We can often get cloud-free images of parts of the UK, but to have the whole country like this is very unusual – a previous favourite is shown on the right from the 18th May 1998 acquired by SeaWiFS that also showed coccolithophores blooming, highlighted in the top image; coccolithophores are phytoplankton with calcium carbonate plates that turn the water milky and so are easily spotted but can sometimes be other phenomena. We know about the issues of clouds as we’ve created a (nearly) cloud-free Landsat 8 mosaic composite of the whole country and had to use multiple years to complete it! We use this archive to create, and support, our Earth Observation products. If you’re interested in such cloud-free images, let us know.

So whilst the British do like to talk about the weather a lot, maybe this time we might have something to talk about.

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