Pressure is falling

This was the pressure this morning. You can see from the marker where it was a week ago. What I find odd is that outside the weather is very much like that for high pressure - settled with clear skies. However the barometer reading is not much higher than when Storm Ashley came through last month and I posted about bombogenesis. With Storm Bert on the way, I will need to watch the barometer.

Not quite the Sea of Tranquility...

... but Tranquility on the sea in the marina. It reminded us of the Apollo 11 landings. The Mare Tranquilitatis was named in 1651 by two Jesuit priests who were early physicists. It escaped being a called the Mare Belgicum. It was an assumption by early astronomers that the dark flat areas on the surface of the Moon must be bodies of water like they would be on Earth but they are actually vast basaltic lava flows.

Looking for the Winter Hexagon

I am trying to get reacquainted with the late autumn sky after the weeks of cloud cover. It took me a while to tell the difference between Auriga and Gemini. So it is Auriga top left. Looking into it brought up another asterism to look for - the Winter Hexagon. I could see the bit from Capella down to Aldebaran but Orion had not yet risen so Rigel was behind the garage. I've now got something to look forward to this winter,

Nuffield Physics

This old tractor in the Penrith Christmas Lights parade was a Nuffield ie one from the works of Lord Nuffield, William Morris. It reminded me of the money he put into Physics education. The Nuffield A Level Physics course was so innovative and was more about developing thinking than learning facts. A lot of the ideas live on here

Kirkwall Power Station

 

I am always interested in how islands are powered. It turns out that this power station is now a back up. It is worth 16MW total. It is oil fired. 

Clouds form over islands

 

It was noticeable approaching Orkney, that in an otherwise cloudless sky, convection cumulus was forming over the islands. My guess is the differential heating of land and sea by the sun. Earth has a lower albedo and a lower specific heat capacity so should get warmer. The vapour later maritime air would get forced up by convection over the islands as a result and condense to form cumulus.

Up to 175kW

 

I've been interested in how quickly you can charge an electric car. This station was claiming up to 175kW. I looked up electric car battery capacities. This source suggests between 60 and 120kWh. Assuming all could be charged at the full rate, and that probably is a big assumption, then it would be between 20 and 40 minutes here.

Jupiter again

Jupiter is back in my evening skies. Two years ago it was prominent in September. Last year it was October. Each year it slips by a month. It has taken the Earth a year and a month to catch up with Jupiter again. Obviously in the mean time, Jupiter has also been moving along its orbit. One month forward every year. There are 12 months in an Earth-year so after 12 years, Jupiter would be back to the same place. The orbit of Jupiter round the Sun must be roughly 12 Earth-years.

Even higher pressure

The new high pressure is even higher than the last one. This needs recording as it may be set to drop quickly over the weekend. 

End of coal

Last time we drove past it was still burning coal to generate electricity but that stopped last month at Ratcliffe-on-Soar. That means no more coal burning to generate electricity in the UK.

Waves taller than a church

  During Storm Ashley we found a link to this site. It gives the live data from the buoys in the Atlantic used to feed weather information to the Irish Met Office. At the time, buoy M6 was recording waves 20m high. That's taller than our church tower!

Anti-cyclonic gloom...

... was a phrase used by Tomasz Schafernaker to describe the weather in the UK under a continent-wide high pressure. It's about as high as I've seen my barometer go and is a good time to calibrate them against a known reading. Mine is really close to the BBC reading for Carlisle so that will do.

The conditions won't be doing much for renewable energy. No sunshine, no wind and no waves!

Cumecs

I was interested in the board for the river flow gauge at The Hermitage near Perth. I'd never come across cumecs as a unit abbreviation. 

Durham Geology Map

I loved this map on the pavement outside the Bill Bryson library. They have done their best to make the stones in the pavement match the correct type found in that location.

Here's Cumbria. Wigton is indeed on some lovely red sandstone - but clearly not our easy wearing type!

Units for pressure

This came through my door. Pressure can't possibly be measured in joules. Those are units for energy. 

Durham Cathedral Meridian Line

I found this notice and looked across the cloisters to see one covered over section.

And below is the view from the other side.

Their website says it is quite recent: 1820s. They made a mark at noon when the Sun was highest in the sky on summer solstice. The mark is on the floor.

Repeated at winter solstice and the lower sun puts the mark higher up the wall.

They drew a line between the two. On any other day, when the Sun hits the line it is noon. Watches and clocks can be set by this. The website says this was necessary because devices were less reliable in those days. This was still before train timetables so there wasn't a standard time across the country. This fixed local Durham Mean Time.

Which I guess means I was wrong about Murdoch Mackenzie's Meridian in Kirkwall. It probably wasn't for surveying purposes as a base line but was to fix accurate local time.

And the pressure has gone right back up again!

An impressive rise of 0.5 inHg in 12 hours. 

Bombogenesis

With Storm Ashley raging around us, I was interested in an article that told me about bombogenesis. This article spells out the definition. My barometer works in inches, so it would be a fall of 0.71 inHg in 24 hours. I last set the reading marker a few days ago and it has come down 0.6 inHg in that time. Not bombogenesis but quite a fall. Reading the article carefully shows that it depends on latitude. I can see how but not why. We are 54 degrees North and would then need a fall of 22mb. I converted my readings and had a fall of 21mb, but I think that was over 3 days not 24 hours. It's got me paying more attention to the baromter.

Murdoch Mackenzie's Meridian in Kirkwall

I found the line in the pavement in Kirkwall. 

I was wondering if Murdoch Mackenzie had been working on the time problem on ships. It turns out he was mapping North Ronaldsay. I thought that this must have been the base line for his map against which he made the measurements. But if you read the post on Durham Cathedral Meridian Line from 22 Oct 2024, it's most likely this is a line to fix local Kirkwall time.

Interesting scale

 

This was in the Botanic Gardens at Oxford. Apparently the Scoville Scale is based on chemical analysis. I was trying to work out whether it was logarithmic. But as it seems to be ranked against variety, which is not a linear scale, there shouldn't be a clear spacing between each level.

Colder inside than out

Strange conditions with a wad of warm damp air coming after the house got cold. There is condensation on the outside of the windows because the cold inside is making the glass surface temperature low enough. 

Projecting onto an oblique curved surface

I went to see the brilliant Katherine Priddy play in a tent. The blue spotlights were circular so the beam must have started circular. It hit the tent canvas in the middle top of the photo, spreading out into an almost parabolic shape. A very clear visual mapping from a circle to a parabola. 

Vapour trail

There is a whisp of vapour trail in the middle of the picture. I watched the plane pass. It seemed to go through the high cirrus cloud. Why did the contrail persist there and not elsewhere? Is it that the humidity is high there so it can't evaporate? Is that why there is a cloud there in the first place?

Tare

 I have been aware of the TARE button on electronic balances for several decades but thanks to Mrs B for pointing out the definition in an old dictionary from over a century ago, as being the mass with the container removed. In recent years, it has often been labelled as the "zero" button. Place the container on the balance and press it to make the reading set to zero. It's interesting that it had a usage similar to algorithm. And its other usage: I thought tares were generic weeds but it seems to be specifically Vetch.

Slight aurora

I was out at 9.30pm on an Amber alert and was able to photograph a faint aurora. I was not able to see anything directly with my eye.

Below is another 9.30pm image

At 1.30am after a Red alert, even the camera was struggling to pick up the aurora. The effect is very variable.

Heavy electric cars

This is because electric cars are so much heavier due to the batteries. Can be a bit of a nightmare at festivals if it gets muddy.

The Perseids

Last night the conditions were perfect. A beautiful clear sky. Sadly I missed any trace of the aurora but in my half hour out I did see two meteors. I had a lovely view of Perseus. I have learnt a new word: radiant. I have enjoyed reading about comet Swift-Tuttle. It is interesting that after its discovery in 1862 that they predicted incorrectly the date of return. With something that has a 133 year orbit, it is hard to figure out on one viewing how long its orbital period is because you have to wait so long. It turns out it had been seen before so that made it predictable. And the dust that it left behind perhaps 1000 years ago gives us our annual spectacle.

How long does a solar panel last?

It finally occurred to me to ask what the lifespan of a solar panel is. I found this information from the States. They are suggesting maybe 25 years. It suggests that they will go past the break-even point but it is not as long as I'd expect a roof to last.

 

Fluorescent watch

Sunlight provides enough energy to move electrons up energy levels. As they de-excite and fall back they release visible photons. A question arises about the time delay. How have they been able to stay excited long enough to de-excite when I go into the dark later?

Back of the fridge

The fridge acts as a heat pump. Thermal energy from the objects inside the fridge is transferred to a fluid and then transferred from the fluid onto the black grill. Now I'm not teaching I can say that it passes by conduction into the metal grill. From there, the thermal energy is transferred to the surroundings. This can be by conduction to air particles, which gives them more kinetic energy making them spread out. The result is lower density air that floats upwards. But there is also heat radiation, the emission of infra-red radiation. This is why the grill is painted black as this is the best emitter colour. The large surface area works well for both methods of heat transfer into the surroundings.

Voltmeters

Unlike an ammeter, a voltmeter must have a very high resistance. In theory, no current should flow through it. If current flows, then a potential difference is set up across the voltmeter. If the voltmeter were connected in series, it would take the lion's share of the available emf in a loop, according to Kirchoff's Laws so voltmeters are in parallel. Even then, unless the voltmeter's resistance is very high it will reduce the current flowing through the component being measured and thus lower the measured potential difference.

 

Haltwhistle as the Centre of Britain

 

I have posted before about Dunsop Bridge's claims. That is done by the centre of gravity of a 2D shape method. Haltwhistle seems to be the the method of measuring the half way point between as many coasts as possible. See here for details. 

Where have all the rainbows gone?

It's been a very showery summer in Wigton yet this morning's rainbow is the first I've seen for a few months. The reason is to do with why the rainbow is such a low arc. Rainbows are centred around the extra-solar point, which is an imaginary point as far below the ground as the sun is above it. The rainbow is part of a circle around that point. When the sun is very high in the sky in the summer, the extra-solar point is very deep so only a small fraction of the circle is visible. This was what was visible early morning in August. For the past couple of months, so little will have been visible and that explains why I haven't been seeing them.

Ammeter

I loved the circuit symbols in the windows of the Electronics Department at the University of York. Because an ammeter measures the flow of current, it must be in series so that it experiences that flow. So as not to interrupt the flow, it must have vanishingly low resistance. If one were placed in parallel to a component, current would flow through it rather than through the component, thus rendering the component useless. In other words, it would act as a short circuit.

 

An interesting approximation

I was intrigued that the sign said "Scandinavia 401 miles (approx). I think it's a clever joke but suppose we took it seriously. Now approximating must mean some decision to round. Here the rounding has been to 3sf and that might be appropriate if the actual distance is measure to the nearest yard or inch. It would work if you are measuring to a point. The problem is that Scandinavia is quite an amorphous concept. Where would we place the point to mark Scandinavia?