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Tuesday 28 April 2015

Sunny interval

This post is intended to raise three questions.

A few months ago Paul Homewood wrote an interesting post on a possible link between UK sunshine, temperatures and air pollution. Because of our recent sunny weather, and long may it continue to warm my old bones, the issue is worth raising again.

Here we have a normalized graph of UK sunshine and temperature from 1929 based on data I recently downloaded from the Met Office. Obvious questions are :-

Is a link between UK sunshine and temperature worth pursuing?
Could air quality be a factor?
Do activists distort our perception of pollution?


3 comments:

Demetrius said...

The trouble is that what is defined as pollution is only what is measured and what is looked for. If there have been a lot of things going on that are not perceived, measured or analysed then we will not know whether there is or is not a problem. My guess is that in the last half century and more so in the last couple of decades we have been putting a lot more stuff in the air than we realise.

A K Haart said...

Demetrius - there is a genuine problem with regulation here.

For example, regulators may list various pesticides for environmental monitoring, but this mandatory monitoring can crowd out the monitoring of newer pesticides.

jpbenney said...

Air quality is certainly a factor linking sunshine and temperatures. This is especially true in very cold months – the very times when sunshine has greatest influence upon personal comfort.

Sunshine measurement in the United Kingdom goes back to 1881 – although a possible proxy based upon cloud cover in London and published in the July 1888 Quarterly Journal of the the Royal Meteorological Society goes back to 1818.

In the early years of sunshine measurement in the UK – which coincides substantially with the coldest period in the CET record since 1700 – one often notices cold months that were generally very sunny in rural parts of the United Kingdom, but quite dull in London. Notable examples include February 1895 – the coldest month over the UK as a whole since 1884 and probably since 1814 (we await figures for January 1881 and February 1855) – when even suburban parts of London had only 40 hours of sunshine, but rural areas of Southeast England had up to 140 hours! Another example is March 1892, which was colder than any March since, but which saw up to 150 hours in rural southeastern England, but only 94 hours in suburban London and probably much less in the city centre. Even the less cold Februaries of 1887 and 1891 saw very substantial sunshine declines in London vis-à-vis rural southeastern England.

However, the declines in sunshine between London and rural Southeastern England were completely inconsistent. For instance, March 1883 – the third-coldest March since 1675 – was very sunny across the UK as a whole but unlike March 1892 saw almost the same sunshine in suburban London as in rural Southeast England. The same is true for January 1891, which followed the infamous December 1890 that saw no sunshine whatsoever in central London, and also saw a latitudinal temperature inversion across Western Europe so pronounced that Baltasound was the warmest place in the UK, and Tromsø was warmer than Paris. In January 1891, Kew averaged 75 hours of sunshine, about two-thirds above normal and comparable to nearby rural areas.