Total Pageviews

Sunday, April 27, 2014

The jet stream(s)

We keep saying that the Jet Stream pushes weather systems around the world.  It just ain't so.  Let me start with a similar situation that occurred in science.

Before the Kiwi scientist, Earnest Rutherford did his work, we had the "Plum Pudding" model of the atom. Lets call this model 1.   Atoms were solid round little bodies packed together with their component parts touching each other.  Rutherford fired alpha particles (Helium nuclei) at a thin gold foil and found that hardly any of the alpha particles bounced back.   Most of them flew straight through the foil with no impedance what so ever.  From this was born the "solar system" model of the atom.  That is to say, most of the atom was empty space and most of the mass of the atom was concentrated in a very small (in relation to the size of the atom) location in the middle.  Electrons orbited around the nucleus like little planets.

This model, lets call it model 2,  was far and away better than the Plum Pudding model but only went so far.  For instance, it didn't explain the peculiar properties of water.  From various other sources, it was realized that water should not be liquid at the temperatures and pressures we have on earth and yet it is.  It was realized that the hydrogen atoms in water are not "attached" on opposite sides of the oxygen atom but rather the water molecule is in a V shape with an angle of 104.5 degrees between the arms formed by the two hydrogen atoms.  This means that the water molecule is positively charged on the Hydrogen side and negatively charged on the oxygen side nd since the positive side is a "naked proton, it has the relatively powerful "Hydrogen Bond"  This explains why water condenses at a much higher temperature than expected, why it expands when it freezes, why it has such a high phase change energy and a number of other peculiar properties it has.

Apparently the orbits of the electrons are not circular as in the planets but, in oxygen, the "p" suborbitals are  like dumb bells at right angles to each other.  Incidentally, this model, model 3, is better than the solar system model but still left something to be desired and later models are even better.

So back to the Jet Stream.

First we have to have a look at the air circulation systems of the earth known as the Hadley cells.  At the equator, the greatest intensity of sunlight hits the earth because the surface of the earth at the equator is at right angles to the sun's rays.  One square meter of incoming sun energy hits one square meter of the earth.  The further north or south you go, the wider the footprint of one square meter of sun radiation.  For the mathematically inclined, you can find how far the sun spreads out by multiplying the one square meter of incoming sun light by the cosine of the latitude.  Cos0 = 1 (at the equator) while cos90 = 0 (at the poles).  Of course this neat picture is complicated by the tilt of the earth.  We could define something called the solar equator and this would be the latitude at which the sun is directly over head at that time of the year.  At the height of summer in the Northern hemisphere, our so called solar equator is at 23 degrees North.

Clear air has some interesting properties.  It is opaque to a little bit of the UV radiation from the sun and this heats up a band of air high in the atmosphere but by far the greatest part of the radiation from the sun passes right through the atmosphere and hits the surface of the earth.  This heats the earth and the earth in turn heats the atmosphere from the bottom.  This effect is greatest at what we have called  the "Solar Equator".

Quite a bit of solar energy falls on the poles at the height of their summer.  However, the poles are covered in snow an ice rather than forests, plowed fields and cities.  The poles reflect much of the incoming radiation right back into space without heating the ground and hence without heating the atmosphere above the poles.  So what results from this uneven heating.

At the equator, with the intense heating of the atmosphere from below, this expands the air and causes it to rise.  In addition, a lot of water is evaporated and as it reaches the dew point, it condenses and gives out it's latent heat.  Air is sucked in from North and South along the surface of the earth to replace this rising air and at altitude, the rising air spreads out North and South.  It moves away from the equator and sinks again at about 30 degrees North and 30 degrees South.   Let's just focus on the northern hemisphere from now on.

At the North Pole, the air isn't been heated at all in winter and not all that much in summer and the air is radiating heat into space.  (every substance which is above absolute zero - minus 273C - radiates heat).  The air cools, contracts, gets heavy and sinks.  At altitude  air is sucked from the south and as this descending air hits the ground it spreads out toward the south.  It rises again at about 60 degrees North.

You will have noticed that we have a gap between 30 degrees North and 60 degrees North.  Between the Equatorial Hadley cell and the Polar hadley cell there is the Ferrel cell which is probably powered by its larger cousins much as an idler gear is powered by the gears on either side of it.

You will notice in this diagram that the surface winds do not blow directly North and South but are scewed to the right in the Northern Hemisphere and to the Left in the southern hemisphere.  This is due to a phenomenon called Coriolis which we won't go into here.

Of interest, though, note that at the equator we have a wall of rising air, between the Northern Hemisphere and Southern hemisphere equatorial Hadley cells  Between the Equatorial cell and the Ferrel cell (not labeled in this diagram) there is a wall of descending air and between the Ferrel cell and the Polar cell, once more a wall of rising air.

The second point of interest, which we see on the following diagram, is that the border between cells does not follow a line of latitude around the globe but waves north and south like a demented sine wave.  These waves are quite irregular and progress from West to East.  They are called Rossby waves.

And note that the above diagram is showing us two of the jet streams.  This is also the border of the circulation cells.  Jet streams occur where Hadley cells meet.You can see where we are going with this.  It isn't the Jet stream that pushes weather patterns around the world,  It is the rising (upwhelling if you like) wall of air or the downwhelling wall of air that occurs between the Hadley cells.  This may sound like nit picking but just as Model three for the atom was more useful than model 2 and 2 better than one,  we are likely to get a far better insight into our earth with a more accurate model.  A more refined model would likely be even better.

Saturday, April 12, 2014

Self Destruction or Rewilding?

We seem hell bent on wiping ourselves out or at the very least wiping out the relatively comfortable, interesting and fulfilling life we now have.

The sooner we admit that we are not as smart as we think we are the better.  Then we might be able to do something about it.

Until recently, the peak of our ecological knowledge dictated that if we wipe out the wolves, we will have more deer to hunt.  Read Farley Mowat's book Never Cry Wolf for a very comical treatment of this myth.  I bet most people "on the street" would still think that this is perfectly correct.

Go to TED talks and type in  the search box George Monbiot or Rewilding or both and have a look at a most erudite treatment of this myth.

We are wiping out species at a rate equal to or greater than during the past 5 great die offs with gay abandon and with little appreciation of the consequences.

Up until recently it was also commonly held that  if you kill all the whales, there will be more krill for fish to eat and hence more fish to catch.  I bet if you asked "the man in the street" you would find he would agree with this also.  George has something to say about this myth too.

And the height of ignorance was expressed by a fisheries biologist that I met in Prince Rupert, BC, Canada who was just off to break up a beaver dam.  He was convinced that beaver dams in streams were detrimental to Salmon and trout.  I mean, How ignorant can you get. You would expect this from a fisherman but not from a biologist.

We are woefully ignorant and the sooner  we realize it, the sooner we may be able to reverse our destructive tendencies.  So what can we do.

Once we have admitted our own lack of knowledge and moreover, our venality in the collective (corporate greed), there is only one solution.  We must set aside large areas on land and in the oceans for nature to get on with what nature does best.

Managed parks such as Kruger in South Africa and all the various other parks in Natal and elsewhere in the world are valuable but there must also be completely untouched areas.  Here is another example of ignorance.

In Kruger Park and other South African Nature reserves, they used to collect dead wood for the fires in the camps.  The accepted wisdom was that this would have no effect on the ecology of the park.  This was stopped when some bright ecologist realized that dead wood is the base for a whole network of organisms.  The cellulose in wood is a polysaccharide.  In other words, a chain of sugar molecules joined together in such a way that the giant molecules are insoluble and refractory to most multi-celled organisms.  Only bacteria can break down the cellulose and many multi-celled organisms from termites to cows have such bacteria in their gut.  In this way cellulose becomes a food source for a whole ecology.

Kruger now brings wood from outside the park for her fires.

If it took so long to realize something so simple such as the role of wolves and whales and of dead wood and of beavers, just how competent do you think we are  to manage vastly more complicated interactions in nature.  We must simply set aside areas which we leave alone.  We can introduce what we believe to be missing components of the ecology but then leave the area well enough alone to sort itself out.  This will generally result in a succession of ecologies similar but not the same as what happened when the continental glaciers retreated from the land.  It will be a source of wonder just what pathways the successions take and a lesson in what used to be and could be in the future.

Look at the story of the return of the wolves to Yellowstone Park.    Here again we have shown our incompetence and venality in our interaction with wolves and the results when we restore missing components and let nature get on with what she does best.  Many of you will be familiar with the story but for a really lucid description, go, again to Monbiot on TED talks.

We also thought we could manage the fisheries of the Grand Banks off the coast of Newfoundland using a simple catch-per-unit-effort model while the catching techniques were ever improving.  How wrong we were there.  For an eye opener of what used to exist around the St Lawrence river area, read Farley Mowat's book, Sea of Slaughter.  Incidentally, some biologists warned against the fishing practices but were shut up by the Canadian Government.  Canada!! for heaven sake.  Considered one of the right thinking, scientifically advanced countries of the world. 

As a further example, just recently, under the Harper government, scientist were muzzled, especially if they wanted to talk out about climate change at threat of their jobs.  What jobs.  The job of a scientist is to speak the truth about what they discover.  These scientist were being paid a salary but they didn't have a job.  If this can occur in a liberal democracy, what must it be like in a totalitarian regime.

If we can't get something so obvious and so simple right, what chance is there that we will manage nature.  None at all.

And why should this lead to self destruction.  With most of us living in cities, we are pretty ignorant of the things nature does for us.  It provides clean air and water, food and fibre, genetic diversity, and a whole range of other benefits.  Besides, nature provides a balm for our senses in this overstressed world we live in.

For that matter, why do we think that us humans, a latecomer in evolution, have the right to wipe out other species who were here long before us.  I wonder if every planet on which life exists eventually produces a species that wipes out the planet and itself with it.

I'd actually doubt that we could wipe out all of humanity.  We are like cockroaches.  Very hard to exterminate.  Lovelock was laughed at when he suggested that within this century, human population would be down to 1b.  We are approaching 7b now so, if he is correct,  6 out of 7 of us won't survive.  He, of course, had no way of knowing just how serious the decline will be but what is pretty certain is that it would be the end of our technologically advanced civilization.  There goes the internet, the mass production of goods by robots which is only viable with a huge market, a sort of Pax UN (as faulty as it is) and so forth.  There goes also our effect on nature and she can begin to repair herself.  Then we will bounce back and do it all over again and again until we achieve total destruction.  Not a pretty picture.

There have been many many empires built up over the last 5000 years or so and all that remains of them is some archaeological remnants and a population of struggling humans occupying the same territory.  On a localized scale we have turned bread baskets into deserts.  The first people who arrived in a new territory wiped out everything their technology was capable of destroying.  European man arrived later and trashed whole ecologies.  There is some hope, though.  In some locations where man has eliminated himself, nature has come back with a vengeance.  A good example is along the border between Italy and the former Yugoslavia along the Soca valley.  In his book Ferral, George Monbiot describes how the Soca valley repaired itself after total destruction during the first world war.  A great read.

Look at North America, for instance.  When Europeans arrived, they were amazed at the richness of the ecology of North America.  Of course they were comparing it with Europe which they had already trashed.  They had no idea of what existed there before the "Indians" arrived.  All the richness Europeans observed was only a remnant of the original pre-human mega fauna.

For the first time, we have a commercially connected world.  We all breath the same air and depend on the same weather systems.  For the first time, as shown by the 2008 mini crisis, what happens in one location effects all of us and as the people in Western Canada will attest, the air pollution from Asia effects them.  I have a friend living on the West coast of Vancouver island.  Their laundry is regularly sullied by Asian pollution.

The ice of the Arctic is disappearing at a rapid rate and prediction of the effects of an ice free Arctic are dire.  It's not that we couldn't live in at least parts of the world under the new climate that seems likely to occur.  It is just that we have used our technology to adapt ourselves to the present climate and have allowed our population to grow to an extent that we are balanced on a knife edge.  A failure of the crops of the Northern Hemisphere for only one year, would send waves of destruction around the world.

I'm sad to say that what we need is a mid level disaster.  Nothing else will shake our system hard enough that we will do something about it.  Let's hope when we do finally wake up, that it is not too late.  This year (2016) is looking like we have already passed a critical tipping point.  2017 will either deny or firm up this impression.

In the mean time, let us set aside  areas as large as we can and leave them alone.  We can introduce remnant populations since often the migration routs have been cut by "civilization" but let nature get on with what it does best.  In Scotland, most major rivers have wide riparian zones. The rest of us should do the same.  These provide migration routs to connect wild areas.    We can even introduce species close to those that have long since disappeared and see how they do.  We are not necessarily trying to re-create what once was but rather an ecology of varied flora and fauna that nature can sort out and which will be a nucleus of recovery if we crash our economy and the rest of the ecology. 

Such areas will also remind us of what richness used to exist in our areas for comparison with the sad remains we have now.  We really need to reset our expectations.  Resetting our expectations may be one of the most important results of rewilding.

Friday, April 11, 2014

The Malasian Airliner

I'm puzzled about the search for the Malaysian Airliner.  Once they had detected even a single ping on the towed array, I would have thought that they would have pretty well pinned down the location of the source of the pings.

Before I explain what I mean, I must admit that my "knowledge" of how these things work is based on novels by authors like Tom Clancey.  However, Tom was said to be a bit of an enthusiast on modern weapons and did his homework.  The basic premises were confirmed in other novels.

As I understand it, when an atomic submarine, either the missle carriers or the attack boats, are on patrol, they stream a long line behind them which is festooned with acoustic sensors (microphones).  I'll explain how they work with simple geometry but of course, the signals detected by these sensors are fed into a computer which gives a virtually instant firing solution.  And as far as I understand, a single ping from an enemy submarine or a noise such as propeller cavitation,will determine its position.

Lets look at the simplest situation in which the target is at right angles to the towed array and right opposite the middle of the array.  The pings arrive at the front microphone and the back microphone at the same time.  This tells you that the target is located somewhere on a disk that intersects the towed array in the middle and at right angles to the array.  In the case of a black box which is pinging, you know it is on the bottom of the ocean so the black box is on a line where the disk intersects the bottom.

However, you don't only have microphones at the front and back of the array.  Let's look at the microphone that is in the middle of the array.  It is closer to the target than either of the end microphones.  It therefore receives the ping before either of the end microphones.  The speed of sound in water is well known.  As the wave front of the ping moves outward, the circle gets larger and larger such that for an infinitely distant target, the wave front is essentially flat.  The difference in time becomes shorter and shorter the further away the source of the ping is located.  From the difference, with modern electronics you get an estimate of range.  In other words, our disk becomes the rim of a bicycle wheel and becomes a solution of the two points where the rim meets the bottom of the ocean.

Now it seems unlikely that all the microphones on the array are omni-directional.  I would assume that there are some directional microphones and the difference in the amplitude of the sound recorded by these various  directional microphones gives you a direction.  In other words, if the "bicycle wheel rim"  intersects the sea bed in two locations, this sorts out which of these is the target.

An added dimension is added when the black box pings for an extended time and the boat is towing an array of microphones.  You are getting a view from a whole bunch of different angles all pointing to a given location. 

The geometry is only slightly more complicated when the ping is in front or behind the array.  In one sense, it is simpler.  If, say, the ping is behind the boat and off to the side, the front and back microphone receive the ping at different times and this indicates in what direction the pinger is located.

Then you have the "passing train" effect.  The pitch changes if the train is coming toward you or has passed and is going away from you.  In this case, the listener is on the train and listening to a stationary sound.  Same effect.

A modern submarine is dependent on knowing exactly where an enemy is located and quickly before they can get off a torpedo.  I can't understand why the location of a stationary source of repeditive pinging is not pinned down almost instantly.   What is all this steaming back and forth over the location to narrow down its position.  They certainly can't be towing an array such as the subs use.

For that matter, why was one of the American or Russian atomic subs not diverted to the location.  Surly they would have pinned down the location within minutes of arriving on location.  Perhaps they have been.  For that matter, they could be pinging themselves and mapping the bottom.  Surly the echo from a bunch of scrap Aluminium would be different from the echo from a soft muddy bottom.

I don't get it.