ISO 400: In the moonlight on Ling Fell

We climbed Ling Fell by moonlight - no torches needed this time. I was trying to get better shots than last week on my very cheap camera. This week I went for the lightest image I could select on the exposure setting and then tried ISO 400. I don't actually know anything about ISO so some work to be done here but we thought that it might make it better. The result is the view of Cockermouth above. ISO alters the sensitivity of the image to light. I was hoping that more sensitivity might mean I'd pick up more light. I'm not sure it works like that because they say it makes the image more blurry. So I've got an excuse for more experiments.

Physik im Advent

You should look at this wonderful series in the run up to Christmas. http://www.physik-im-advent.de/ The German Physical Society are posting a short video clip of a fun experiment every day. They ask a question and post the solution the next day. You don't need great German to follow what's going on. I shall be trying some of the experiments myself.

Upside down Moon in Australia

Here's Grasmoor with the Moon on Sunday afternoon. During the walk I was asked how this could be the same Moon that is seen in Australia or New Zealand. I know that it has to be but that it will not be visible to them at the same time that it is visible to us. The rotation of the Earth brings us past the Moon and away again, then bringing them past the Moon. So I emailed friends in Sydney and in New Zealand asking for photographs. I got a surprise this afternoon looking at the photographs. If you enlarge my photograph, you'll notice that the right hand side is lit. It's a half Moon. By the time I received the photographs, the phase had moved on to 3/4 Moon, but look carefully at the picture below from Sydney and you'll notice that it is the left hand side that is lit up, not the right. So from Australia the Moon does appear to be upside down. Wow! There'll be more on this when I've done some thinking.

Bird-on-a-wire potentials

Last night I heard a wonderful lecture by Dr Harald Fox from Lancaster University. He was explaining the need for the Higgs Boson. He started with Noether's Theorem. Emmy Noether was a brilliant mathematician who proved that if you have a symmetry in nature, then you will have a conservation law. I'm beginning to get my head round this so there will be a some posts about it to help me to understand it. One example of a symmetry is that of electromagnetic potential. He described it as a "bird-on-a-wire" potential so I was very pleased to spot this bird this morning. Normally they perch on the very top wire, which is the earth wire and has no current or potential. This bird was perched on one of the lower wires. Judging by the number of insulators, I'd say the lines would be at least 10,000V. So why isn't the bird hurt? The answer is because both legs are at 10,000V. You need a potential DIFFERENCE to get a current to flow. As long as the bird only touches wires at that potential, there is no difference and the bird is safe. If we transferred the bird to a higher voltage line, say 425,000V, then the same thing would apply and the bird would still be safe. Provided there is no difference in the voltage (potential) for each leg, then the bird will be safe wherever. That's what we call a SYMMETRY. You can change the condition but get the same result. The overall situation looks the same although we have changed one condition. So we have a symmetry with electromagnetic potential (voltage). There must be a conservation law connected with it. In this case, it is conservation of CHARGE. And that's what we check when we are looking at particle interaction equations to see if they will work.

Drying the homework

I had an accident and my water bottle leaked onto the homework. I have dried it out and it has now been marked. But consider this method of drying on a radiator. I was taught that radiators are badly named and that they work principally by convection. This is true. If you hold your hand above a radiator you can feel the warm air rising. So why would you hang things next to a radiator? Try holding your hand a couple of centimetres from the side surface. You can feel warmth. That will be infra-red thermal radiation. White is said to be a bad emitter of radiation (remember that white reflects all the colours) but the point is that it is a bad emitter of visible wavelengths. It does emit quite well at infra-red wavelengths, so the homework dried. See the previous post about Leslie's Cube for more information http://wigtonphysics.blogspot.co.uk/2014/09/leslies-cube-and-why-my-physics-teacher.html

Hypothesising on Blake Fell

When we were driving down to Loweswater, Blake Fell was clear. When we arrived, the mist had settled high on the sunny side of the fell. It was a still day and got me thinking. My hypothesis is that the rising sun started to increase the evaporation on the sunny side which increased the humidity. That then took the amount of water vapour in the air above the amount needed for saturation at that temperature. Then it cleared at lunchtime, probably because the air temperature had risen and was no longer at the saturation level.

We looked across to Grasmoor in the afternoon. There was a cloud stubbornly lingering in the high corrie to the right of the summit. It stayed there all afternoon. So I came up with a hypothesis that the lack of wind inside the corrie would allow the humidity to remain high enough by not shifting the water vapour. The horizontal wisp of cloud half way up the cliffs was another interesting feature. It also persisted at exactly that level. Could that be to do with the temperature decreasing as you go up to be low enough for saturation at that altitude? I'm not sure how true all of this is but I have had a great time coming up with theories and thinking about them.

Cirrus cloud over Castlerigg Stone Circle

I spotted these clouds yesterday afternoon. Cirrus are very high - over 5km up in the atmosphere. It might be below -20 degrees Celsius up there. Thus they are made of ice crystals rather than water droplets. The winds are very strong at that height so the clouds are strung out and are shaped like commas. They form ahead of a warm front. Oncoming warm air is pushed up above colder air and condensation happened. The front arrived overnight. It did feel like a warm night to me.