No second helping of aurora

I tried again twice on Saturday night. At 2am, it was a 200nT Red Alert on the app. Nothing doing. In the morning I found this article here. I was interested in the classification of a G4 geomagnetic storm. Turns out there are several ways of measuring the strength of a geomagnetic storm but the G scale is from the US. See here for info.

Aurora at last

This was the alert. 

This is what the camera saw. To our eyes, much less colour and looking like cirrus at weird angles. Also wasn't expecting it south of the house. 

Zero Error

I have been noticing that the altitude readings on my app is always about 50m too high. The viewpoint on Brock Barrow has a spot height of 223m so the screenshot below confirms that magnitude of zero error. 

Oscilloscope app

Turns out I have a sound oscilloscope app. Here's me whistling. 4 cycles in 3ms means T=0.75ms. Frequency = 1/0.00075 = 1300 Hz which sounds about right. 

Under the M6

I got under the M6 at Carnforth. Not surprisingly the thick concrete is a decent sound insulator. 

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.