Calm sea in Silloth

For some time I have been interested in the idea that the sound of the sea at Rhosilli camp site last summer was as loud as the wind  turbine at Kessingland. So I've been out with my deciBel meter. Trouble was the sea was very calm when we went to Silloth. I went right down to the edge of the sea.

 66 dB is about as loud as a conversation.

You couldn't even see the sea up in the car park. It suggests the sea was as loud as a refrigerator hum or even rustling leaves. It was louder at Rhosilli!

Polarisation in Wigton

I was talking to my class about the picket fence model for polarisation. Transverse waves are ordinary wavey-looking waves like the waves on the sea. Waves that vibrate in the vertical plane would be able to slip through the gaps between the fence posts. Waves vibrating in the horizontal plane would not. It's a good model but more complicated than that in real life. If the electric field of an electromagnetic wave lines up with the poles, which could be metal or organic molecules, it makes electrons in the poles oscillate so using up energy and thus stopping the vertical electric field electromagnetic waves. Ones with horizontal electric fields can only make electrons vibrate a tiny lateral distance in the poles, thus horizontal waves can get through. This is opposite to the picket fence analogy!

Standard wire gauge and knitting needles

I went down to the library to join the knitting group. You can see my efforts at the top. Knitting needles are now measured in mm - their diameter. I am using 4mm needles. My micrometer screw gauge reads 4.01mm so the needles are accurately labelled! Older needles have a more archaic numbering system which means that the thinner the needle, the bigger the number. It turns out they used to be measured in standard wire gauge. A "28" needle, if it existed, would be as narrow as the copper wire pictured. My 4mm needles would be 8 in standard wire gauge. If you want the history of wire gauge, try this https://en.wikipedia.org/wiki/Wire_gauge. Basically, the number told you how many times the wire had been pulled through the machinery. Each pull made it thinner. Hence bigger number, thinner wire.

Stationary wave on the M6

One of the joys of motorway travel is getting stuck in queues. You can be there for half an hour making very little progress. You get to the front of the queue thinking there must have been accident, but there's nothing there and you just drive away. So why were we queuing? There must have been a cause earlier on, like someone braking hard, and then because everyone else braked, a queue develops. It becomes an enduring pattern - a stationary wave. The pattern stays in place on the road even as each individual car moves through it. Eventually it disappears when the traffic density is low enough for the stopping distances to become much bigger.

Crossing the continental shelf

We crossed the edge of the continental shelf. The crust of the deep ocean beds is made of mafic rock like basalt which is denser and sits deeper. The continents are made of felsic rock like granite which is less dense and sits higher. Once the hills like Skiddaw behind Wigton were on the edge of the continental shelf - mudstones deep underwater. Then we collided with Scotland which threw them up as mountains.

The power of water on Catbells

We found this remarkable channel on the path up to Catbells from Grange. I assume it was cut on the floods weekend in December. Look at the stones piled up against the wall at the bottom. Let's say 1 metre high by 10 metres wide 1 metre deep. That's a volume of 10 cubic metres of rock. The density of rock is about 3 tonnes per cubic metre. That's 30 tonnes of rock shifted. Maybe not as much as I'd thought. What impressed me the most is that the water had such power given the short run-off. It looks like it gets about 150 metres of stream bed. I'm thinking about possible equations. I'd like to apply Newton's Second Law as F = v (dm/dt) where the final term is mass flow rate but the velocity of the flow is not constant because it is accelerated by gravity.

Is evaporative cooling responsible for the ice?

Two consecutive days and very different underfoot. My impression was that the air temperature was about the same each day but we were sliding along on sheet ice in the top picture. The top picture came with gale force winds. It was flat calm in the bottom picture. My hypothesis is evaporative cooling. The wind keeps shifting particles away from the surface. This would lead to higher rates of evaporation for water. It is the most energetic particles that escape first. Those that remain have lower energy therefore the temperature is lower and would thus be more likely to freeze.