Colorimeter photos and resolution

 

We used the absorbance scale, which is the bottom scale with the black numbers. The smallest scale divisions are every 0.05, which means that the resolution is therefore 0.05.

Here are the filters we used to find lambda max.

Here is the all important zero button.

Meniscus

 Liquid has surface tension. The particles would normally bond in all directions but at the surface they can only bond sideways and downwards. This means more bonds than usual are formed sideways creating tension. Where the liquid touches the side of a container, these bonds hold on. Gravity makes the liquid sag downwards in the middle. The sag is called the MENISCUS.

We always measure to the bottom of the meniscus.

Here are the two pieces of measuring equipment we used in class so that you can see the resolutions.

Rain before seven, fine before eleven

 Here is the scene first thing this morning.

By quarter to 11, the first sign of fine weather was beginning to appear in the west over the Solway.

My parents taught me the weather saying "rain before seven, fine before eleven" when I was a child; we were trying to be optimistic on wet holidays on the west coast of Scotland. When I became a teacher, an early lesson was that very few students had been taught it by their parents! It is based on the four to five hour transit time of an Atlantic front across the UK. It often doesn't work in mountainous areas like this one because the mountains can catch the cloud, especially if the weather is coming up from the Azores as it was the other week. But today it looks as though it's going to be all right.

Angles morts: blind spots

 

In France, the warning to cyclists and motorists about where they cannot be seen seems to have been called the "angles of death". In English, we call them "blind spots". The French is better. It is the physics that fixes this. Light travels in straight lines and cannot pass through metal. I'm interested that it includes a space right in front of the vehicle where the driver would not be able to see down.

Thirlmere Aqueduct at Greenhead Gill, Grasmere

 

The water from Thirlmere goes to Manchester through a tunnel that needs no pump - the water flows due to gravity alone. However, there are points where the gradient of the tunnel takes it above ground level. One such point is Greenhead Gill at Grasmere so they had to build two bridges to take the aqueduct out of tunnels and above ground. This included a change in direction. There is a brilliant film about the project that includes a visit to the site to be found on the Institution of Civil Engineers website https://www.ice.org.uk/what-is-civil-engineering/what-do-civil-engineers-do/thirlmere-aqueduct-and-reservoir

Gassy lava near Dockey Tarn?

 On the way up towards Nab Scar from Alcock Tarn, I found this boulder inn the path. There are rows of little indentations.

I was wondering if it was artificial but it continued into rocks nearby. This means that it is probably due to gas bubbles in lava. But why would the bubbles be so uniform in rows? It doesn't look as though there were repetitive layers forming on layers and that in each the bubbles rose to the top. So a mystery.

We went on to visit lonely Docket Tarn which sits on one of those wide ledges that is characteristic of the lava flows in the Borrowdale Volcanics around St John's in the Vale.

Optical corona: reflections in Alcock Tarn

 The Sun was shining through thin high cloud, enough to produce an optical corona. Having posted last year about optical coronae in steamed up glasses due to mask wearing, I thought this was an unusual way to capture the optical corona of a different kind. This isn't the corona that is the outer layer of the Sun; rather, it is what happens is diffraction through water droplets. In fact, I think the bit I saw is the aureole - see http://www.atoptics.co.uk/droplets/corona.htm