Equipotential at Sty Head Tarn

 Retreating high water had left a mark linking places of the same height - a natural equipotential.

What is causing the "waterfall" of cloud?

It was a cloudy start after the stormy weekend but by lunchtime the sky had cleared over Birks. However there was cloud tumbling over the top of Hart Crag and down into Deepdale like a waterfall. How does that work? For there to be cloud, the humidity needs to be at or higher than the saturation level for air of that temperature. Today I suspect that the cloud on the west side of the hills reflects moist air coming in from the sea which would increase the humidity. Where I was standing the sun has increased the temperature so that the air is no longer saturated. My hypothesis is that the cloud is tumbling over the shaded side of the hill where the sun is not reaching so the air there will be colder and become saturated more easily. I'll need to remember to look next time to see if it happens over sunny slopes.
 

The range of a micrometer screw gauge

I've taught about the resolution of a micrometer screw gauge before (+-0.01mm) but I've not considered the maximum reading. This would be called the Full Scale Deflection (FSD) on an analogue electrical meter - the largest reading on the scale. Turns out that for the micrometer it is 25mm.
 

What is inside a digital thermometer?

 A broken thermometer gave me the chance to look at the temperature sensor.

Using a magnifying glass, I could see what looks like a glass bead with two clear contacts inside. It doesn't look like a thermistor. So it could be an RTD - resistance temperature detector. I hadn't realised there was so much to think about. I learned a few years ago about the relative merits of 2-wire and 4-wire probes but this article even includes 3-wire probes.

After the first 100 moves

 This is where I've got to after 100 moves. It does reflect the probabilities quite well.

Quantum shuffling update

 It's coming on but to get a full view I'm going to need about four times as many moves. I think that I have calculated the number of microstates for J incorrectly. Update soon.

Quantum shuffling day 3

 Today there was a lot of shuffling between different microstates in E

Quantum shuffling day 2

 After another 20 moves, the pattern is beginning to emerge. Macrostate E has taken off. 

Starting the quantum shuffling

 I was wrong yesterday about the macrostate with the most microstates. I finally got round to making a chart showing the macrostates and their number of microstates. You'll see below that macrostate F has more microstates than J.

                                       

So I started the quantum shuffling with the dice from state A, the most unlikely. After 20 moves the oddity so far is state I which has been far more common than expected. It could be an artefact of starting from an unnatural point.

The most microstates

 Back to the quantum shuffling game. By my calculation, this is the macrostate with the most microstates.

I tried to list all the possible states that began with 12 on Level 2. I found 6.

Then I realised that 13, 14, 15, 16 would follow the same pattern. As you start to put other numbers onto Level 2, you get some repeat patterns so the number of extra microstates falls. In the end, I think there are 76 possibilities.

Trying to measure the angle between two rainbows

 There was a good double rainbow visible and with the ends clearly touching the ground, I thought that they seemed a long way apart.

I had a go at measuring the angular separation using the fingers method and managed to get my whole hand in. My little finger at arm's length is worth 1 degree. I'd estimate 6 degrees here. https://www.metoffice.gov.uk/weather/learn-about/weather/optical-effects/rainbows/double-rainbows suggests about 10 degrees so it really is quite a big separation.

Making a noise in Bitts Park

 I found this instrument in Bitts Park Carlisle a while ago. You bang the xylophone but there are pipes behind.

The xylophone bars are fixed - this one is 10cm apart. If the fixture points act as nodes then the wavelength of the stationary wave is 20cm. Assuming speed of sound of 340m/s that gives frequency of 1700Hz. It was nowhere near as high as that!

The pipe behind was about 15cm long. Given an antinode at each end, the wavelength is 30cm and the frequency 1100Hz. I still don't think it was that high. I will have to wait until I'm allowed to go again to test my memory of the pitch.

Green filters reflect green

 

Teaching about a green filter, I would say that white light hits the filter, red and blue are absorbed and green is transmitted through but it must also be true that the green reflects as well. In the case of the guide light for Silloth harbour, it is the case that some green light will be transmitted and then reflected back through the filter by the shiny light casing I could see inside, but it was mostly looking green to me because green light was reflecting from the outside of the filer back towards me without being transmitted. This will be why filters make the world seem darker because not only is part of the light absorbed but also part of the transmitted colour is actually reflected without going through, reducing the possible transmitted intensity.

A buzzing tree on Wedholme Flow

 

There was such a strange buzzing noise coming from half way up this tree that we stood awhile looking for some type of insect, though it seemed too early in the year for that to be possible. It turned out that it was a piece of bark being on our side being vibrated backwards and forwards. Our side was the side away from the wind, so my guess is that there was some kind of vortex shedding going on as the wind passed the tree - a bit round one side and then a bit round the other way. But is that possible if the tree is not vibrating as a wire would in the wind? Trees are flexible enough to move slightly and maybe that is enough coupled with the variability of the wind flow. Though thinking about it, it is probably the vortex shedding up and down that actually makes the wires move up and down, not the vibration causing the vortex shedding.

Floating ship mirage

 This story has been going round the Internet https://www.bbc.co.uk/news/uk-england-cornwall-56286719 It is an amazing image. A superior mirage diagram is here https://upload.wikimedia.org/wikipedia/commons/5/54/Superior_and_inferior_mirage.svg It looks like it happens in temperature inversion conditions and that light travels faster in warmer air than in colder air. This will be because warmer air is less dense. I shall now be more aware on days of temperature inversion in the hills. Having seen the Brocken Spectre last year, it would be great to see a floating object!

A surprise spectrum

 The bevelled edge of the mirror acted as a prism producing a pleasing spectrum today. Since the light hadn't bent through in the normal way, there must be some reflection involved.