Porphyritic granite on the Pentland Road

Hello There's a cutting on the Pentland Road about 2 miles east of Carloway with an obvious vein of big crystal granite in it. Looks like it has intruded  between earlier layers. BGS viewer suggests a vein of Uig Hills - Harris Igneous Complex which could be around 2 billion years old.

The phenocrysts are very like those in Shap granite. 
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But it's quieter inside the car!

Sat inside the car it is 10dB quieter. 

Motorway noise

From right by the motorway. In the 80s of decibels. 

Snowshoes!

These are how snowshoes were in old physics books. They are on the wall of the Tiso cafe in Perth. My feet are approximately 25cm long by 10cm wide. Total area of both feet = 500 square cm. One snowshoe looks to be made of 2 triangles that are 30cm x 30cm and 70cm x 30cm giving area of one snowshoe as 1500 square cm. Total area of both = 3000 square cm. So with the snowshoes the pressure is 1/6 of what it would be. I still find it hard that they are not solid. How does the mesh work?

Not a sundial!

I have got so used to public sundials that I was confused by this. The "gnomon" points east. Then I realised there were no times on the seats.And then that the seats were on the wrong side. Whoops! I'm getting conditioned. 

How long do rainbows last?

This year I am trying to count the number of rainbows that I see. Sometimes the shower stops and the rainbow disappears only for it to start again in roughly the same place a couple of minutes later. Is that a new rainbow or a rainbow that has been paused? There was one part-rainbow that endured for over 10 minutes. There were a series of rainbows that followed the one above and due to the lengthy gaps between the showers, the position of the sun had shifted which meant you could tell the rainbow was not aligned the same way over the loch. Rainbows in waterfall spray can presumably last all the daylight hours and must subtly shift orientation as the sun moves. Philosophically, is a rainbow even a thing at all? Anyway, the questions on ephemeral phenomena are keeping me entertained.

Solar powered!

This truck intrigued me. I wondered if it were a portable solar power unit. But looking at the other side, I wonder if it is actually a solar-powered advertising display.