What happens when National Grid power lines cross?

 Just outside Great Orton, two sets of power lines cross each other. If you look at the pylon on the right in the picture, there are lines coming into it from behind and then they stop. The lines are sent into the ground and go underground beneath the cables shown.

They emerge later at the pylon below. There are shielding grids between the down-cables.

I've tried to find out more about these pylons but the best I have found so far is here.

A Pebble map of Geology

 This is a map of the area around Teesdale in which each pebble is of the correct rock type for the location it marks.

The slates on the left hand edge are the oldest and date from a collision of continents. That will be Scotland and England crashing into each other.

I've known about that for years but this display helped me to realise how far south of the Equator we must have been when that happened because the limestone formed on top of it in coral seas. And the Whin Sill intrusion happened before the red desert sandstone, which I understand was laid down when we had made it as far north as the Sahara is today. So the map turned out to be a bit of a gem that made sense of a set of facts I'd known but never put together.

The Whin Sill again at Low Force

 

Having previously encountered the Whin Sill on the other side of the hill at High Cup Nick I shouldn't have been surprised to find it in Teesdale where its harder rock causes the waterfall at Low Force. However, it did bring home to me the extent of this intrusion. It ends on Lindisfarne; I found it at Dunstanburgh and also on Hadrian's Wall. 

Calculating the efficiency of my candle

 

I took some results for my candle water-heater and I tried to look up a value for the Joules per gram of candle wax. I found 43kJ and 37kJ so let's say 40kJ per gram. 0.28 grams of wax burned which releases about 11000J. It was set up so a 1 degree Celsius rise in temperature is worth 100J so that means 3140J of energy went into the thermal store of the water. If we are using this candle as a water heater, then the efficiency = 3140/11000 = 0.28. The rest is dissipated to the surroundings as heat and light (heating by particles and heating by radiation in the new parlance). Presumably I would get a higher efficiency if I moved the candle closer, say 2cm instead of 3 cm.

24 cubic centimetres of water

 

We set up this experiment to show that the chemical energy store in a candle empties and the thermal energy store of the water fills. We had the candle 3cm below the tube and we heated for 2 minutes. We weighed the candle before heating and again after. The mass went down slightly showing that the chemical energy store of the candle had emptied. We measured exactly 24 cubic centimetres of water into the tube and measured the temperature at the beginning and end. The 24 cm^3 was chosen because with that volume, the thermal energy store of the water has increased by 100J for every 1 degree Celsius rise in temperature. Not all of the chemical energy from the candle goes to fill the thermal store of the water. Some is dissipated as thermal energy into the surroundings so just by knowing the energy absorbed by the water, we cannot be sure of the actual energy that left the candle. However, I may have a way of attacking this problem and finding the efficiency.

Robin Rigg Wind Farm: bigger turbines

 

Robin Rigg wind farm was visible on the horizon in the sunshine from Southerness Point. I looked up the turbines. Like Watchtree, they are Vestas but this time V90. The serial number refers to the diameter: they have 90m diameter whilst the V47s at Watchtree are 47m. The wind speed for cut in, rated and cut out are the same. These big turbines generate 3MW as opposed to the 660kW of the smaller ones. The swept area of the big ones is 3.67x the smaller (6362m^2:1735m^2). However 660 x 3.67 = 2.4Mw so there is more to extra power generated than just the extra wind energy gathered.

A visit of the centre of England

 

We stumbled upon this whilst out in Sutton Park in the West Midlands. Having been to two rival claimants for the centre of Britain (see this post) I think this is much more likely to be correct since the dispute on the whole of the Britain depends on whether or not you include the Northern Isles. This is probably also done by the centre of mass cardboard model method. And here's what the centre of England actually looks like:

Reaction timer ruler

 

I turned a metre stick into a reaction timer by recalibrating the scale to read in seconds. The idea is that one person holds the ruler vertically level with the top of another person's open hand. When the ruler is dropped, the second person catches it and their reaction time is read from the scale. I used one of the Equations of Uniformly Accelerated Motion to work out the scale division. I used s = ut + 1/2at^2. This reduces to s = 1/2 x g x t^2. Since distance is proportional to t-squared, the linear gaps get bigger.

A lovely film about renewable energy on Eigg

 I'm hoping to visit Eigg and found this lovely film about their ground-breaking renewable energy scheme which involves linking wind, solar and hydroelectric with a battery bank as well. 

An interesting statement about ultrasound

 I bought a new ultrasonic scarer for mice. It is interesting to note that cats and dogs can hear some ultrasound but that this is pitched too high for them.

Most physics teachers would be aghast at that the statement that "ultrasonic waves behave in a similar way to light": hey! Ultrasound is a longitudinal wave and light is transverse - it's  a bad source of exam confusion. But hold on! Actually, the point being made here is that ultrasound will not travel through objects either. Given its use in pregnancy scans, it would be understandable if people thought it was. You need saline gel to get the ultrasound to go into a body and that only works because the speed of sound in saline gel is the same as in muscle. Even saline gel would probably not get ultrasound into furniture - and it would be messy....

Apparent brightness: Wigton lights

 

The Wigton lights have been lovely this year. There were stars hanging from the strings across the street. These were all identical stars but illustrate one point about the brightness of the stars we see in the sky. Here in Wigton we can see the distances between these stars but we can't tell when we look into the night sky. Everyone understands instinctively that if something is further away but intrinsically the same, it will appear to be dimmer to the observer. It follows an inverse square law: doubling the distance means there is a surface 4 times as big over which to spread the light energy. The brightness is therefore reduced to 1/4 of what it was.

Vesta V47 turbine at Watchtree

Watchtree have placed the old generator from a turbine on display. It prompted me to go looking for information on the turbines. I started here. I found that they are quite old turbines made in Denmark called Vesta V47. Each one can generate 660kW. Even better was the information on the turbine type. I always love a graph and if you scroll down it shows what to expect for each wind speed. Translating into miles per hour, it needs 9mph to get generating, hits full power at 33mph and shuts down at 56mph. The turbine forecast for tomorrow is 68% which I assume means 68% of 660kW = 450kW. From the graph that means wind speed of 10m/s which is 22mph. The BBC forecast for Wigton is for 16mph tomorrow. Watchtree is exposed so the prediction is not unrealistic but it has to be really windy to generate full power.
 

A mystery solved : Langmuir circulation

 It's taken 5 years but I have finally found the answer to a question I raised in a previous post. I've been reading John Muir's book First Summer in the Sierra and he mentions seeing what he calls "windrows" on a lake. These lines of foam turn out to be what I've seen on lakes too. They are odd because whilst wavefronts form perpendicular to wind direction, these windrows form parallel to wind direction and I couldn't see a mechanism to do this. Turns out it is called Langmuir circulation. Now I need to work out how the wind makes these vortices under the surface of the water.

Winter high pressure causes renewable energy crisis

 

The notice at Watchtree said that the solar powered card reader wasn't working. This has been a UK-wide problem in the second half of December because an area of high pressure settled in but gave cloudy skies instead of the clear blue skies often associated with a high. So solar electricity was severely reduced at the same time that very light winds reduced wind power to almost zero. Diversity of sources will help us to cope. But as we make cash in Wigton, there was still the option to donate that way.

Vacuum fluctuations at Farmoor

 It was a very calm day at Farmoor Reservoir.

We did spot the Great Northern Diver.

It occurred to me that even on a calm day the surface of the water is not perfectly still. Looked at closely, small ripples are visible. This reminded me of the amazing discovery that a vacuum is not a smooth emptiness but is a seething mass of virtual particle pairs popping into and out of existence due to energy fluctuations based on Heisenberg's Uncertainty Principle. https://en.wikipedia.org/wiki/Quantum_fluctuation

How I missed Comet Leonard

 

I have started looking at APOD again after over a year away and found that there has been a comet around this last year https://apod.nasa.gov/apod/ap211227.html Unfortunately it seems that it has now become a southern hemisphere object https://www.skyatnightmagazine.com/advice/comet-c-2021-a1-leonard/ It shows that I need to resolve to pay more attention this year!