Archive for December, 2016

Still learning after all these years

December 31, 2016
David Archer teaching a course on Global Warming

David Archer teaching a course on Global Warming

I have had to teach myself the physics of global warming.

And as an autodidact, I have suffered from the misfortune of having been taught by an idiot.

So ‘attending’ an online course about Global Warming is a genuine pleasure: it is so much easier than teaching oneself!

All I have to do is to listen – and re-listen – and then answer the questions.

Someone else has selected the topics that they feel are most important and determined the order of presentation.

Taking the course on-line allows me to expose my ignorance to no-one but myself and the course-bot.

And in this low-stress environment it is possible to remember the sheer pleasure of just learning stuff.

On line courses

Using the FutureLearn platform, I have taken courses on Global WarmingSoil, and Programming in Python.

I have participated with dual aims. In part I have wanted to learn about the topic. But also I have been curious to experience ‘a course’ from a student’s perspective.

The current course uses the Coursera platform and is much more technical than any of the Futurelearn courses I have tried previously.

For me that’s fine, but my guess is that the mathematical level is somewhere between GCSE and ‘A’ level and many people would find that intimidating.

The course assessments are also genuinely challenging, requiring the use of quite complex online software, and implicitly, the use of a spreadsheet or calculator.

One pleasing aspect of the course – for me at least – is that the course lecturer (David Archer) basically stands in front of a blackboard and talks.

He dresses like a physicist, and sounds like a physicist, and makes mistakes on the blackboard – it’s just like being back at University!

And in the vacuum between Christmas and New Year it has been a pleasure to lose myself in this on-line world.

Continuous Professional Development

‘Attending’ this course has also had a curious personal resonance for me.

I recently applied to become a ‘Fellow’ of the Institute of Physics – I am currently ‘only’ a member.

I first filled out the application form in 2013 – three years ago – and I thought I was doing well until I came to the section marked ‘CPD- Continuous Professional Development’.

The section was marked with a stern warning that it was not optional. Unfortunately, I couldn’t think of a single word to put in the section. So I just forgot about the application.

Each year since I have re-visited the form and fallen at the same hurdle.

But this year I asked some colleagues for help. It turns out that attending courses like this is actually CPD!

Who knew!

 

 

Grandmother’s kilograms

December 28, 2016

weight-2016

One of the reasons that I feel better this Christmas than last is because I have managed to lose weight.

In the 11 months since the end of January 2016 my weight has fallen from about 88 kg to around 73 kg.

For US readers, that’s a weight loss of 33 pounds, and for older UK readers, that’s about two and a half stone. It is a transformative amount of weight to loose. I feel much better.

I mention it here, because I have showed similar graphs before. For example, in 2011 I wrote “The Mass of Sisyphus” which has a graph of my weight from 1995 to 2011 (Ages 35 to 51)

So I have achieved similar weight loss previously, but previously my weight crept back onto my body. However I don’t have any data about the times when my weight is increasing.

It is like the game of Grandmother’s Footsteps in which children have to sneak up on ‘Grandmother’ but they can only move when ‘Grandmother’ is not looking.

Similarly, my weight seems happy to stay still or indeed to go down, as long as I weigh myself every day. But when I stop weighing myself – it slowly creeps up on me in the most sinister way.

My conclusion is that in order to maintain my weight I need to weigh myself every day.

It is yet another example of the power of measurement: because it is not until one measures a thing that one can begin to understand it, and control it.

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The graph also shows the busy year I have had with trips to Canada just before the graph began, India, the USA (twice), Poland, Italy and Spain.

Irritatingly, each trip has broken my weight loss trend.

However another good feature of the year has been running. Compared with 2015, I have increased the distance I have run from about 14 km per month, to around 100 km /month.

running-record-2016

Running has helped keep anxiety at bay and happily I can take my running shoes with me when I travel.

This seems to have settled down into a routine, and although it seems quite sporty for a man of my age (57) it takes only just over two hours a week.

And as I have run more, even though I haven’t been trying to run faster, I found I have naturally speeded up.

running-speed

Looking at the graph I can see that even since July 2016 when my weight has been more or less stable, my speed has been slowly increasing.

So my aim for the new year is to keep on running – and weighing myself every day. And hopefully I will keep Grandmother’s kilograms from creeping up on me!

 

 

 

Happy Christmas 2016

December 24, 2016

christmas-card-2016-explosion-3

First of all, thank you for having taken the trouble to stop by.

I had been going to write my reflections on the year – but I am too tired, and too likely to say negative things. So I will put that off for now.

And looking back at my blog, I realise that I do feel better than I felt in 2013.

All the things I wrote back then are still true, and some even more so.

But my campaign to manage my own anxiety has partially alleviated their personal impact. So there are positives from the year!

But horrifically I also realise that I am struggling to complete exactly the same ‘3 month’ project that I was desperate to complete by last Christmas! Aargh

Hey Ho! “plus ça change, plus c’est la même chose!” Anyway, please allow me to wish you a…

…Happy Christmas, and a splendid 2017.

 

 

When will the North Pole become the North Pool?

December 16, 2016

arctic_ssi_201612_chart

It is a sad fact, but it is likely that within my lifetime it will become possible to sail to the North Pole. I am 56.

Tragically it is also true that there is absolutely nothing that you or I can do about it.

In fact, even in the unlikely event that humanity en masse decided it wanted to prevent this liquefaction, there would be literally nothing we could do to stop it.

The carbon dioxide we have already put in the atmosphere will warm the Earth’s surface for a few decades yet even if we stopped all emissions right now.

Causation

The particular line of causation between carbon dioxide emissions and warming of the arctic is long, and difficult to pin down.

Similarly it is difficult to determine if a bull in a china shop broke a particular vase, or whether it was a shop helper trying to escape.

Nonetheless, in both cases the ultimate cause is undeniable.

What does the figure show?

The animation at the head of the page, stolen from NASA’s Earth Observatory, is particularly striking and clear.

The animation shows data from 1979 to this past November 2016 showing the extent of sea ice versus the month of year.

Initially the data is stable: each year is the same. But since the year 2000, we have seen reductions in the amount of sea ice which remains frozen over the summer.

In 2012, an additional one million square kilometres – four times the area of England Scotland and Wales combined – melted.

The summer of 2016 showed the second largest melt ever.

The animation highlights the fact that the Arctic has been so warm this autumn, that Sea Ice is forming at an unprecedentedly slow rate.

The Arctic Sea Ice extent for November 2016 is about one million square kilometres less than what we might expect it to be at this time of year.

My Concern 

Downloading the data from the US National Snow and Ice Data Centre, I produced my own graph of exactly the same data used in the animation.

The graph below lacks the drama of the animated version at the head of the article. But it shows some things more clearly.

sea-ice-december-2016-graph

This static graph shows that the minimum ice extent used to be stable at around 7 ± 1 million square kilometres. The minimum value in 2012 was around half that.

The animated graph at the head of the article highlights the fact that the autumn freeze (dotted blue circle) is slower than usual – something which is not clear in the static graph.

My concern is that if this winter’s freeze is ‘weak’, then the ice formed will be thin, and then next summer’s melt is likely to be especially strong.

And that raises a big question at the very heart of our culture.

When the North Pole becomes the North Pool, where will Santa live?

 

Why I love thermocouples

December 6, 2016

 

img_4656

Thermocouples are probably the simplest, cheapest and most reliable temperature sensors available.

But like many pieces of great technology, their simplicity hides a mystery!

The Mystery

A thermocouple is made of two different kinds of wire, joined at one end and connected to a voltmeter at the other end.

figure-4

When heated a thermocouple generates a voltage approximately proportional to the temperature difference between the junction of the two wires and the two loose ends of the wire.

This is really useful – and by using standard types of wire – humanity can measure temperatures in a simple way.

And the mystery? The mystery is that none of the voltage you measure is generated at the tip of the thermocouple!

How a thermocouple works

In 1821 Thomas Johannes Seebeck discovered that accompanying every temperature difference in a metal, a small voltage was generated: a ‘thermo-voltage’.

figure-1

We now know that it is caused by the differing extent to which the electrons in the metal are disturbed at different temperatures.

Seebeck noted that the voltage generated for a given temperature difference depended on the type of metal.

figure-2

So a copper wire stretched between two temperatures generated one voltage, (V1), but a nickel wire stretched between the same two temperatures generated a different voltage (V2).

In a long wire, a voltage is created across the length of the wire, and one can work out the total voltage measured by adding together all the small voltages (ΔV) due to all the small temperature changes (ΔT).

figure-3

Interestingly – and this is at the heart of the mystery – because the ΔVs are only generated by ΔTs – it doesn’t matter how long the wire is, or which route it takes!

The thermo-voltage is proportional to the overall temperature difference between the two ends of the wire.

Joining two types of wire together

A ‘thermo-couple’ is made by joining two dissimilar wires together. Because the two wires are different, the voltages V1 and V2 generated by each ‘leg’ of the pair don’t cancel, and there is a net voltage (V1 – V2) characteristic of the two types of wire, and the temperature difference from one end to the junction.

figure-5

 

So if you know the temperature of your voltmeter, then you can work out the temperature of the tip of the thermocouple by measuring the thermo-voltage.

The ‘thermo-voltage’ is usually tiny, typically only 40 microvolts per 1 °C of temperature difference, but that’s enough to make a measurement with an uncertainty of about 1 °C in many circumstances.

The Mystery

From the explanation above it should be clear that the ΔVs are generated along the entire length of the wire – but no voltage is generated at the junction!

If one puts a thermocouple in a furnace – then the ‘thermo-voltage’ corresponds to the temperature at the tip of the thermocouple. But all the delta ΔVs  are generated as the thermcoouple goes through the wall of furnace!

figure-6

If one pulls the thermocouple through the wall, then a different piece of wire generates the voltage.

So in order to get reproducible results it is important that the composition of the wire is uniform along its length. This is one of the major problems in the making thermocouples and being confident they are reading correctly..

A thermocouple thermometer

A thermocouple thermometer is actually two thermometers in one!

  • First the device has a thermometer inside – usually an electrical resistance thermometer called a thermistor – that records the temperature of the electrical terminals.
  • Secondly the device has a sensitive voltmeter that records the ‘thermo-voltage’. Based on the type of wires from which the thermocouple is made, the device works out how much hotter or colder the tip of the thermocouple is than the electrical terminals.

Combining the results of the two temperature measurements together gives the temperature of the tip of the thermocouple

Interesting places to stick a thermocouple

Because thermocouples are small and tough and light, you can stick them in places that you can’t easily stick other thermometers. You might like to try these experiments:

  • Let some ice warm up to 0 °C – and then press it down on some salt with a thermocouple trapped underneath. The temperature will fall to roughly -16 °C – really cold!
  • Try putting just the tip of the thermocouple in a candle flame. You should get an answer close to 1000 °C!
  • Try working out just how hot a cup of tea is when its just right – for me it’s close to 60 °C.

It’s hard not to love a scientific instrument that can do all that!

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Global Warming Trends

December 3, 2016

 

The anomaly in the Earth's temperature based only on thermometers in meteorological stations and excluding the oceans which cover about 70% of the Earth's surface. The Daily Mail only draw your attention to a small fraction of the data - and they include monthly fluctuations which disguise the clear warming trend.The anomaly in the Earth’s temperature based only on thermometers in meteorological stations and excluding the oceans which cover about 70% of the Earth’s surface. The Daily Mail only draw your attention to a small fraction of the data – and they include monthly fluctuations which disguise the clear warming trend.

Why do I ever even look at the Daily Mail website?

The other day I came across this pernicious article purporting to describe a plummeting of global temperatures above the land surfaces of the Earth. The article states:

Global average temperatures over land have plummeted by more than 1C since the middle of this year – their biggest and steepest fall on record. [P.S. by 1C they mean 1 °C not 1 coulomb]

The news comes amid mounting evidence that the recent run of world record high temperatures is about to end.

Some scientists, including Dr Gavin Schmidt, head of Nasa’s climate division, have claimed that the recent highs were mainly the result of long-term global warming.

Others have argued that the records were caused by El Nino, a complex natural phenomenon that takes place every few years, and has nothing to do with greenhouse gas emissions by humans. The new fall in temperatures suggests they were right.

It is accompanied by a misleading graphic:

Graphic from the Daily Mail website. Notice their graph only runs from 1997 and includes large fluctuations due to sub-annual changes. It describes only the changes in temperature above the land surfaces of the Earth.

Graphic from the Daily Mail website. Notice their graph only runs from 1997 and includes large fluctuations due to sub-annual changes. It describes only the changes in temperature above the land surfaces of the Earth.

The article is nonsense from start to finish, but I just thought I would show you how to get at the data for yourself so you can make up your own mind.

Decide for yourself

This excellent NASA web page allows you plot various graphs of temperature data, and change the degree of smoothing applied to the raw data. I invite you to try it out for yourself.

This NASA web page has excellent links and descriptions

You can choose to include land stations only, or combine land and ocean data. Remember that the land surface of the Earth represents less than 30% of our planet’s surface, and so the most relevant measure of global warming involves both land and ocean data.

As well as generating graphs, you can use the website to download data and then graph the data in Excel™ as I have done for the graph at the top of the page.

I don’t fully understand where the data in the Daily Mail graphic comes from. They appear to have picked only recent data and included monthly data rather than annual averages to increase the noise and de-emphasise the obvious trend in the data.

The background colouration in the Daily Mail graphic implies that the high temperatures are all associated with the El Nino conditions. This is not correct. As the graphic below (from skeptical science) shows, years with and without an El Nino are all showing a warming trend.

An animated file showing global surface temperatures in El Nino years, La Nina years, and neutral years. The graphic is from sceptical science.

An animated file showing global surface temperatures in El Nino years, La Nina years, and neutral years.

For the technically-minded reader, this article from Victor Venema may help.

The Trend 

What struck me as shocking was what happened when I set the smoothing of the data to 20 years – so that the trend represented a trend in climate rather than annual or multi-annual fluctuations.

In the figure below I show the data for the land and ocean mean temperature anomaly and the red line shows the smoothing with a 20-year running average. Since 1980 – which was 36 years ago – the data is essentially a straight line.

The estimated change in the temperature of the air above the oceans and the land. The red line shows a smoothed version of the annual data with a 20-year window to reflect changes in climate rather than the internal fluctuations of the Earth's complex weather systems. Source: NASA-GISS: see article for detailsThe estimated change in the temperature of the air above the oceans and the land. The red line shows a smoothed version of the annual data with a 20-year window to reflect changes in climate rather than the internal fluctuations of the Earth’s complex weather systems. Notice that since 1980 , the smoothed line is essentially straight with a gradient of approximately 0.017 °C per year. Source: NASA-GISS: see article for details

What if…

Friends, just suppose that NASA had spotted not a global warming trend, but an asteroid headed straight for Earth. Suppose they calculated it would not destroy civilisation, but it would nonetheless be devastating: its tidal disturbance would cause widespread floods

Would we want to know? Well Yes!

Now suppose that the entire world got together in, say, Paris, and developed a plan to deflect the asteroid. The plan would be expensive and risky – costing about 1% of global GDP – but after about 100 years of effort we would be freed from the risk of a collision.

Would we follow the plan? Well Yes!

Friends, Global warming is equivalent in its impact to an asteroid headed to Earth, and the Paris Accord, while inadequate in itself, represents the start of a plan in which the disparate governments of Earth have agreed to slow development (that brings direct benefit to their citizens) in order to tackle this threat.

Please don’t let the Daily Mail deceive you into thinking global warming is not happening: it is. It is happening slowly – 0.017 °C per year  – and the odd year of inaction makes no difference.

But year upon year of inaction condemns us to a fate that is out of our control.

 


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