Microscope graticules and woolly fringe-moss

 I found the slide graticules for our microscopes. I also viewed my ruler again below to show that the numbers are in millimetres and the smallest scale divisions are 0.1mm.

 I found some moss on the summit of Skiddaw that I hoped was Racomitrium lanuginosum (Woolly Fringe-moss). https://rbg-web2.rbge.org.uk/bbs/activities/mosses/Racomitrium%20lanuginosum.pdf The key feature is the toothed hair point.

Ultra-violet water filter

We found this water filter at Skiddaw House. The frequency of UV is of the order of 10^16 giving a photon energy of the order of 10^-17. Since ionisation energies for carbon, hydrogen and oxygen are 10^-18, the UV can ionise the atoms in living organisms. It can damage the DNA in micro-organisms, killing them. Flow rate needs to be slow enough to allow all the water to be adequately treated but fast enough to stop it overheating. http://filterbutler.com/blog/what-does-a-uv-water-filter-do-and-how-do-they-work/

Skiddaw Metamorphic Aureole 2: Sinen Gill

 Sinen Gill is famous as one of the three places that the underlying Skiddaw Granite reaches the surface. I went looking for the join between the granite and the metamorphosed country rock. I couldn't find the precise place mentioned in the guides but did find the weathered section mentioned.

 I found a large white piece of granite by the stream and there was weathered granite. The rock above, in the picture above, is not granite. I think that is hornfels. So I think this must be where the granite met the country rock. If so, then the temperature 400 million years ago would have been over 1000 degrees Celsius. The metamorphosed rock is brittle in the correct physics definition. It breaks without deformation, but then all rock does. It's just that it breaks into square blocks whereas the original Skiddaw Slate breaks into flat sections along the layers.

Skiddaw Metamorphic Aureole part 1

We went up Mungrisdale Common by way of Sinen Gill. A granite intrusion breaks the surface in the gill and is surrounded by the well-known Skiddaw Metamorphic Aureole. The Skiddaw Slate has been changed by the heat of the magma welling up. This is contact metamorphism. In the distance in this photograph is another gill where we first found evidence of metamorphism. It is about 1km away. I looked up the temperature of magma and perhaps 1000 degrees Celsius would be a ball park figure. I was wondering about modelling the conduction of the heat from the magma through the slate. From https://en.wikipedia.org/wiki/Thermal_conduction heat flux density q=-k.(temperature gradient). So temperature gradient is likely to be of the order of 1 degree Celsius per metre. A value for the thermal conductivity of slate is 2W/mK. Of course, that is roofing slate so it isn't the same thing. But it would give a heat flux density of the order of 2000W per square metre.

A random walk experiment

I have been trying to understand electron diffusion equations in conductors. One is based on a random walk model and gives the probability of finding an electron at a given place at a particular time. It contains a term for the dimension of the space. I was wondering what would happen if I simplified it to one dimension. So I got a coin and tossed it 100 times. I said I was starting from position 0 and moved one to the right for HEADS and one to the left for TAILS. I tossed the coin 100 times. I haven't done that since my introductory maths class on probability in 1978!

I got 52 heads and 48 tails. The position ranged from -2 to 10. Here is a bar graph showing frequency.

It might be heading towards a bell shape. Maybe I would be able to get a Gaussian distribution eventually. I thought I'd been quite smart coming up with this idea but now I've got wifi again I can see that this is a common strategy. This link even computes the probabilities https://en.wikipedia.org/wiki/Random_walk

Sound reflecting from the mountains

Another thing that struck me as the planes went past was that mountains reflect sound quite well. I suppose that should come as no surprise because you can hear echoes but they are usually in tight corries with well defined craggy backwalls. What I noticed was that out on the open fellside, I watched the plane go past, "saw" the sound follow it and then yet there was a distant rumble from behind - the sound of the plane reflecting back from the mountain slopes behind. It's just surprising because it isn't a good reflecting surface. I now teach about diffuse and specular reflection of light. A sheet of paper reflects light but you can't see your face in it because the light is sent in all directions producing a diffuse reflection. That's probably what the mountain is doing to the sound.

Precise snowline in Langdale: rain starts as snow

It had been raining in the valley bottom at night. The very precise snowline around Langdale last week brought home to me that that same rain had been falling as snow half a mile away, and that up the hillside, movement of a few metres must have meant moving from rain into snow. So the conclusion is that all precipitation starts as snow and then melts as it falls. http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/fcst/prcp/rs.rxml Now I'm thinking about the thermodynamics. How quickly can the thermal energy from the warmer air flow into a snowflake and cause a change of state? It clearly isn't an adiabatic process.