Thinking about cloud streets

At Silloth the wind was coming in from the right. The cumulus clouds formed distinct lines. But are these cloud streets? This site seems to imply something closer and more tubular. However they seem to tie in with the description of formation. 

Calibrating my barometer

You are supposed to wait until there is a settled high pressure before adjusting but that hasn't happened in the last two months! I have set it to the Carlisle Airport figure given on the BBC Weather website. It seems to be staying about right. We were wondering whether modern double-glazed houses would affect the readings. I can't find anything on that but did find this site about where to put them. It is on an outside wall about head height and nowhere near a radiator so that should be right.

Euphotic zone data

 

I found this data at the aquarium in Maryport

I put the depth and intensity data into a spreadsheet. I'm guessing that light intensity will fall exponentially with depth in the form I = B.exp(-kd) where B and k are constants.

This seems to be true because I get a straight line.

Mercury maximum elongation

My book told me to get out at 7.30pm to see Mercury. The arrow shows Jupiter. Mercury was in the circle but the sky was to bright there for it to stand out in the photo. It has led me to find out what elongation means. It turns out that it refers to an angle. It is the biggest angle between the Sun and the planet as seen from Earth, so I suppose it must make it seem furthest from the Sun and in Mercury's case, makes it easier to see.

Testing the bin lid

I realised I have a dB meter on my phone. The bin is rated 89dB so not far off but my conversation was this loud! 

Comparing electricity supply sources

 It must be mandatory now to show sources on bills. Here are a couple I've been shown:

The second makes a point of being 100% renewables.

The bottom of a lightning conductor

 

I noticed that the lightning conductor was double thickness at the bottom - made of two parallel strips. I wondered if that was a standard feature but I haven't been able to find anything. However I did find this brilliant article. I hadn't considered what happens below the ground. So the system needs to take the current away from the building. In this case I'd hope towards the graveyard because directly away from the building was towards a house a few metres away! 

Glow sticks

There were glow sticks at Laura's party! I've always known that flexing the case breaks a chemical container inside allowing two chemicals to mix. Looking up the details here has got me doing some thinking. It says that the reaction is exergonic. This seems to be because the reaction is at constant temperature. The graph seems similar to the one I taught for exothermic reactions but they would release heat and presumably the temperature wouldn't remain constant. The energy released seems to excite a dye compound, meaning that the electrons go up energy levels. They de-excite by releasing a photon and if the dye is chosen so that the energy levels produce photons that lie in the visible range, we have a glow stick. Would we still call them glow sticks if there were photons released but not visible to the human eye?

Sensing the temperature

There is a brass-coloured cylindrical piece of metal clipped to the back of the heater. It is then attached to the thermostat control by a long bare piece of wire.

Somehow this must be sensing the temperature behind the heater. The mechanism sounds like a bimetallic strip kind of sensor. Perhaps the long metal wire is conducting heat here not electricity!

Increasing the surface area

This electric wall heater has two heating elements. The device has a switch that toggles between "half" and "full" ie one element connected or both. There are thin metal plates that sit perpendicular to both, with the elements going through them. These are to increase the surface area. The idea is that when the air touches the hot metal, there is transfer of thermal energy by conduction. The more metal that is touching the air, the more of this can happen at once and the faster the air heats up. The air expands, becomes less dense and rises. This allows colder air from below to move in to touch the plates.

Heisenberg on In Our Time

Lord Bragg of Wigton has a big interest in Physics and has done a lot to promote the subject. Heisenberg was the subject of a recent In Our Time. Towards the end, a contributor describes starting out to draw a wave as a series of points. When you draw the first point, you know a lot about the position. But you need to add more points in order to figure out the wavelength. With more points, you know less about the position. Hence particle and wave properties cannot be fully known at once.

Another lichenometry data point

It occured to me that the slates on this roof are also a way of measuring the rate of growth of the type of lichen that grows on the cemetery wall, which is half a mile away. The slates are 75 years old. So this shows that the lichen is increasing in diameter by about 2mm a year or 1mm in any ditrection.

Dark Side of the Car

I lived this vehicle. The image is one of the first bits of Physics that I remember. My Year 9 teacher was at pains to point out that the colours should be split in the middle of the prism too and not white. 

Beautiful Belt of Venus picture

 APOD had a fab picture last week which went beyond just the Belt of Venus. More sections of the sunset sky to examine and understand now.

Wheelie bin decibel level

I don't know why I'd never noticed before but I was amazed to notice that the wheelie bin had a decibel rating. It turns out that it is a warning about the noise made when the lid slams down. See here. There are lots of decibel scales on the Internet. It suggests that this is somewhere between a loud truck, a shouted conversation and a hairdryer. One difference is duration - the lid slam doesn't last long.

Potential well in Dalby Forest

I was really impressed by this structure in the adventure playground at Dalby Forest. It really does look like an inverse square potential well. 

Situated in the outer surround, it is a brilliant representation of the nucleus and alpha radiation. The alpha particles would have to use quantum tunneling to escape through the sides of the potential well.

Shap Granite erratics at Robin Hood's Bay?

We found these two boulders on the beach at Robin Hood's Bay. They could well be glacial erratics. There was always a stone opposite the Radcliffe Science Library in Oxford that was a glacial erratic of Shap Granite brought back from Filey, I think. It shows ice moved in that direction. I suppose they could have been brought as sea defences but sea defence boulders are usually all of the same type. Also the coast is not being defended!