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Sunday, 5 January 2014

Weather.

I was just listening to an item on the radio about Ice Fairs on the Thames. I think the last one was 1814 if I remember rightly. I assume that not only has the weather been warmer since then but maybe the flow of the Thames has increased due to it's banks been developed and the bends narrowed so concentrating the flow making it more difficult for ice to form. I am in the camp that believes that all man made addition to the atmosphere will be having some affect on it. I also understand that there have been fluctuations in the climate for ever, and I don't mean just the ice ages etc, as there has been great fluctuation during and between ice ages. In the past it may be thought that the atmosphere was self correcting as in when there were great volcanic episodes the extra CO2 in the atmosphere helped in the evolution of plants and trees and these grew terrifically using the extra CO2 and producing O2 to bring it back to a balance. When you add in the unnatural man made additions to the atmosphere it is difficult to think that they will have no effect.

When I learned my meteorology the line of depressions moved up and down with the season. So in our summer the winds bands moved back towards the equator and this meant that the depressions moved south of us and were less frequent. In our winter the bands moved north and so the lows tracked over, or to the North of us. This may still be true to a certain extent but it certainly seems that this year they are more fierce than we have known for a long time. There is an item in today's Sunday Times that postulates that this is because the Equatorial Jet Stream has changed from an easterly wind to a westerly. Jet streams are rivers of fast moving air at the tropopause, about 12km up, and at the major front between warm and cold air masses. The main one is the Polar Jet at about 60 degrees latitude and the Sub Tropical Jet Stream at 30 degrees. The Polar Jet is the strongest due to the higher temperature difference between the air masses. They say that this has added impetus to our own Polar jet Stream that is always westerly. (ie blowing from the west). I had never heard of the Equatorial Jet stream before, and I had never heard of one changing direction of flow. I had heard of the sub tropical jet stream and as far as I knew this was always a westerly anyway.




Northern Hemisphere jet streams. Polar Jet Stream is the Mid Latitude Jet stream on the Diagram.
https://www.fas.org

Maybe they ear taking about these much more minor seasonal jet streams that are also much more variable and could conceivably change direction that would then maybe increase the strength of the Sub Tropical jet, which in turn could strengthen the Polar  Jet.


 Equatorial jet streams?
http://www.wunderground.com/blog/Weather456/understanding-the-atlantic-hurricane-season-tropical-jet-streams-the

I find the study of climate fascinating as the world is so interlinked that it is almost true that the flap of a butterflies wing can cause a hurricane half way round the world, as said in Chaos Theory. Our weather has a lot to do with the temperature of the sea and this is affected by the ice caps etc etc., and we have all heard of the El Nino Effect.

I hope you haven't got bored and switched off as I'm really not banging on about global warming, man made or not, although I would say that it makes good sense for each of us to do a little bit to prevent pollution just as we will save money by doing so. I was really wanting to say we should not underestimate the power of the weather and especially water.


These people should be very careful indeed as they may just but somebody else at risk trying to save them.
www.mirror.co.uk

Be very careful when moving about on the water as we may get away with it once or twice but maybe not the third time, and in the end is it worth it.


Winter 2012 saw 75% increase in call outs for River Canal Rescue with claims at £1.9 billion.

It is always wise to take precautions, like mooring from under trees when gales are forecast.

30ft Scots Pine across the Chesterfield canal.

Is it therefore any wonder that the British are well known for talking about the weather all the time. Carry on consulting the weather forecasts as 'forewarned is forearmed' as my Granny used to say.

Stay safe out there.

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