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Jet Stream

29 April 2015

For those unable to attend our AGM and Spring meeting they missed a real treat. Both talks were excellent and videos of them will be uploaded in due course (after a bit of work by Chris Phillips). However, the transcript of Bob Johnson's talk is already there (go to meetings page) and has the title 'The variability of the Sun and the effects on Earth' so you can settle down later in a comfy armchair with a print-out or simply scan the piece from your computer chair. Unfortunately, I don't know for the moment how we can get around those elderly members not on the internet and who would likewise be very interested in reading what he has to say.

The presentation outlines how the Sun affects the weather on Earth – and suggests what might make the Jet Stream tick. We have all heard of the Jet Stream as the Met Office constantly tell us about its changing position – and how when overhead we get bucket fulls of rain and when we are inside or outside a loop it can either be cold, or  unusually hot.

How do we get from how the Sun works to how the jet streams perform in the atmosphere of the Earth. Bob Johnson begins by saying space is not a vacuum (as once thought) but is filled with plasma. The atmosphere of the Earth is not an electrified insulator either – but a weak plasm. This is an important point as it enables the Sun to play around with our weather – which is a fundamental change in thinking. Plasma can form cells and filaments and behaves differently to other gases. It has been described as a fourth state of matter. The presentation is written in a clear and concise manner and is designed to be transparent for a popular audience and the general public at large and is free of as much jargon as possible. It explains everything about plasma (well, almost) and how it is capable of conducting electricity. It can also contain magnetic energy embedded within itself – under the right conditions. Plasma has been the subject of research for a century and scientists know a lot about it – and so on.

The solar wind plasma is deflected by the Earth's magnetic field and this induces a complex system of electric currents which input energy to the magnetosphere and the ionosphere. The input depends on the velocity of the solar wind and the presence of a plasma filled solar wind interacts with the plasma in the Earth's atmosphere (and ionosphere).

Later, when looking at jet streams, which are quite narrow bands, he says they behave somewhat like plasma – or are influenced by plasma. In addition, sea water is an insulator and it is known that El Nino events and other ENSO cycles (the movement of ocean currents around the globe) move in synchronism with solar activity. We are essentially a water planet so this point is interesting to say the least (not least the role of evaporation and the formation of clouds etc).

Bob Johnson has produced an impressive presentation and quotes a host of scientific papers by people such as Akasofu, JA Eddy, H Alfven, Thomas Gold and Fred Hoyle, Lockwood, Zhang, Feng, Svalgaard, Svensmark, Vahrenholt and Luning, Wang, and so on (being just a few names that immediately ring a bell, although some of the others will, I'm sure, ring the door bell later). A terrific piece of endeavour to bring all this together and present it in such an easily digested manner. Highly recommended even if you are non-scientific, and let's face it, we've all heard of the jet stream but not many of us know what it entails, what it does, and what makes it move around and change our weather.

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