A Matter of Physics

A Matter of Physics

 

As a youngster, I watched my brother-in-law making a hash of felling a tree! Not that I understood fully what I had seen, nevertheless I learned something from it. His business was a cartage contracting and he had won the contract to remover the old pine trees from the boundary of a racecourse that was being shut down. We’re talking about the mid-1950’s when there wasn’t the equipment there is nowadays.

 

Jack had a three-tonne truck and hooked a wire rope onto the tree about four metres up the trunk and the other end was hooked onto the truck. He put a front scarf into the butt of the tree and almost cut it through on the back cut. He them hopped into the truck to pull the tree over. The truck skidded a bit on the dewy grass, so he stopped to reverse to give it another tug, which was enough to cause the tree to rock. What was left of the wood in the back cut let go, and backwards went the tree, pulling the truck backwards, with the wheels sliding on the dewy grass. There was a six-foot fence behind the tree, then a footpath, a street, another footpath and a house. The fence went ‘ping’, the electric wires on one side of the road also went ‘ping’, the telephone wires on the other side of the road did too but the tree missed the house. It took the rest of the day to clean the mess up and the power and telephone companies were none too happy… nor the house owner!

 

Jack didn’t understand the physics. The truck didn’t even have duals on the back, so there were only four points of contact with the grass. And traction was limited because of the dew… it would be better to have a heavy load on the tray, to provide more traction and make it heavier for the tree to pull back. The higher up the tree the rope is attached, the better the purchase and less actual weight that needs to be pulled. A couple of wedges driven in on the back cut could have probably toppled the tree or at least taken the rocking out of the equation. It was lucky he had insurance, and the street was quiet.

 

Much later, I used my little one and a half tonne utility truck to pull over a lot of trees. Loaded with firewood or perhaps gravel, I used my truck as an anchor. I didn’t use wire rope, instead I used the malleable number eight fencing wire, which can pull four tonnes. I climbed the tree and hooked the wire where there was about six inches of diameter. Mostly I didn’t use wedges, instead used a chain-wire-strainer so the pull never let go. Before my back cut had gone in very far, I took the strain with the wire strainer, so the tree couldn’t go back on me, I would then cut almost as much as I judged was enough, and pulled more with the wire-strainer. Normally the hinge wood worked like a hinge and the tree would topple, but it gave me the opportunity to cut more one side or the other to directionally fall the tree, leaving holding wood. I never had a mishap.

 

Sometimes advice falls on deaf ears and that happened with Richard, who worked as a breaker-out in a contract logging crew I kept my eye on. Breaker-out is the term for the guy who hooks the rope onto a tree for the hauler to pull it out of the forest onto a landing. I noticed Richard was hooking the rope well up the stem. I explained that the rope needed to be hooked onto the very butt of the tree for reasons of physics. The butt might hit a stump, or other immovable object, which might stall the hauler, but more likely cause the butt to jump over the object. But if the rope is hooked further up the stem, the butt will stall on the object, but the rope will keep going and the head of the tree will come around in an ark… and at lightning speed! Well… a couple of days later, I was called up to an accident! Richard had hooked a log almost half-way up a tree, the butt had jammed and the swinging tree had hit him on the thigh! He was wearing anti-ballistic trousers, but the force had broken the bone in two places, without the trousers, it would have taken the chunk right out! It took forty minutes for the ambulance to arrive and while I had a work crew cut a track to carry him out, I tried to make him comfortable and stayed with him. Morphine and oxygen did wonders while we carted him out of there.

 

When you’re my age, a quarter of a century doesn’t seem so long… anyway, I used to take weather readings for the met. office for twenty-five years, and taking those measurements is a branch of physics. A metbox is a ‘Stevenson screen’, which is a white box with slatted sides at ‘breast height’ above the ground. It’s your ‘temperature in the shade’, so isn’t really the outside temperature, but a standard measurement used around the world… and to track the trends in temperature, the met. office doesn’t like moving the boxes because it breaks the timeline. What I found was the microclimate around the boxes changes very quickly, in our case ornamental plantings blocked out the cold winds and intensified the frosts. Many of the metboxes around the world are located at airports which were originally grass strips, but now are sealed and have buildings around, another complication is the heat from aircraft and motor vehicles alters the maximum reading. Some metboxes are in the CBD with heat influences from buildings, asphalt and vehicles.

 

What does this mean? Generally, that the temperature in cities and built-up areas is warmer than areas outside those areas, which means that warming isn’t necessarily to do with a change in the world climate, but that of a microclimate. The other error is that to achieve a daily mean temperature, from which a mean annual temperature can be found, the daily maximum temperature and the daily minimum temperature are added together to achieve the mean (average). According to my mathematics teacher averaging averages is bad practice… but for this it is within a whoop and a holler. But the maximum only needs to reach that temperature for enough time to move the mercury up the tube! The biggest failing is what I found in my measurements… the maximum was only marginally warmer because of the shelter but not withstanding the colder frosts, because of the shelter, the night remained warmer thereby lifting the average temperature, so at an airport or in a CBD, asphalt and concrete buildings don’t cool down as much at night.

 

There were times when my forestry crews were working in gulleys, when the still air increased the temperature significantly more than on ridgetops, so a thermometer was taken with them and I pulled them out at 40°C… they were usually in direct sun so the thermometer was placed in the sun. Our potting shed in the nursery was made of corrugated iron and had no lining the reflected heat off the iron could reach 40°C plus too, but we kept working. Conversely, in frosty weather, it felt warmer in the cool store than in the shed and the coolstore was set at 3°C. I took a thermometer with me to Tanzania and one Saturday afternoon, working by myself, I thought it was hot, so I sat the thermometer on the ground… it was 45°C. There was a heatwave in the UK while I was there and in response to the news items, people complained about the heat… but although I didn’t carry thermometer, my phone said it was 29°C, and I didn’t think it was excessively hot. Was it mind manipulation by the media? These days a heat wave is an unusually hot temperature, night and day for three days… it used to be five days and whose opinion is ‘unusually hot’?

 

There’s no need to be a scientist to understand how the temperature record is at least dubious, so what of the scientists? We hear a few speaking out, they are the ones who have retired, but the majority keep mum for their own reasons, and they do have reasons… if your job depended on not telling the truth, what would you do? Here’s the cause; eighty-four counties signed up to the Kyoto Protocol… well their political representative did, and others have since signed up making 192 in all, and there is the Carbon Trading Scheme. Those countries like to show they are green by reducing carbon dioxide because of the theory a warming planet is going to be a catastrophe… which could be argued is an anti-green policy because if we reduce carbon dioxide, we are robbing the food source from plants (y’know, those green things that support life on the planet). Anyway, the politicians in our country say if we don’t do the green thing by reducing our carbon dioxide emissions, nobody will trade with us… inferring, but not saying they will block incoming trade from counties that aren’t reducing their carbon dioxide emission, yet we still trade with China and right now we’re busy courting India to get a trading agreement. I’d be surprised if other western countries weren’t doing the same. So, we are compromising our economy because our representative at a COP meeting was stupid enough to sign up to the Kyoto Protocol… and many countries are in the same boat. And I’ve been around the globe a bit and never have I seen produce libelled from a green country… it’s simply political clap-trap.

 

Of course, the climate changes, it always has, but there’s no empirical data anywhere that says armegeddon is approaching or even that extreme weather events are getting worse or more frequent, but there is data to say that resilience and good economies are the key to mitigating extreme weather events. The trouble is a couple or more generations have been through schooling and university where they have been indoctrinated that carbon dioxide, global warming and severe weather events are linked… and all because the simple physics of temperature measurement has been corrupted.