Meerkats and Infra-red at the Safari Zoo

Here at the Meerkats at the zoo in Dalton. There's an infra-red lamp to keep them warm. Why does infra-red feel warm? Try Googling that question - it's quite a controversial topic. Perhaps it is because we absorb more at that wavelength. My pale skin is obviously not a classic absorber at visible wavelengths but we don't know what "colour" it would appear at infra-red.

Vapour trail shadows on Little Hart Crag

I posted before about this topic in August and was unclear about what had caused the darkened lines on the clouds. Yesterday it was obvious. The shadow even moved from the right of the Sun to the left of the Sun as the clouds blew. But looking at the top picture, the vapour trail must have been much higher than the alto-cumulus layer than it seemed. There was an equal angle subtended between Sun and vapour trail and vapour trail and shadow. It was about 5 degrees.

Testing gravity in Dovedale

We tested gravity on the way down from Dove Crag. The question was whether a heavier stone would fall faster than a lighter stone. So let's test it. The answer is that they hit the ground at the same time. You can explain it like this: Take two smaller equal sized stones and drop them. They are bound to hit the ground at the same time. Drop them right next to each other. It won't change anything. Now glue them together. They won't suddenly fall twice as fast because you have one block that is twice as heavy. You can split any large block into equal sized smaller blocks and work the process backwards. And this is what we do. We define gravitational field strength as the pull on a 1 kg block. It is force per unit mass. It is the PER that is important. Big blocks are made of smaller blocks but gravity acts PER 1kg block so all blocks fall at the same rate.

h rho g at Glencoyne Dam

Glencoyne is the most wonderful hanging valley above Ullswater. It clearly had a mining past. This dam is in the valley floor. It must have had an earth filling. I've never seen a drystone wall dam before. The height of the dam must have been about 2 metres in the middle. Pressure in a liquid is directly proportional to depth (or height h of water above me). Pressure = h.rho.g where rho is the density of water - 1000 kg per cubic metre. g is the gravitational field strength, 10 newtons per kig on Earth. So water pressure = 2 x 1000 x 10 = 20000 newtons per square metre. That's like 2 tonnes on 1 square metre or a car balanced on a square metre. A car wouldn't go through a double wall filled with earth.

Temperature inversion on the Solway

It was a clear night last night. We could see the cosmos, which has an average temperature of around 3 Kelvin. As such, it emits very little black-body electromagnetic radiation. The Earth's surface is much warmer at maybe 280 Kelvin so it radiates more. The net effect is that thermal energy is lost from the surface of the Earth. The air next to the surface becomes cold enough for water vapour to condense and a layer of mist forms. The upper atmosphere receives thermal radiation from the Sun first and will be at a higher temperature so the mist seems trapped at ground level. Normally the air temperature is warmer at ground level and lower higher up. This is the other way round: a temperature inversion.

Fibonacci pine cones in Wreay church

I first heard about the Fibonacci Series and the Golden Ratio years ago. I've never bothered to look into it. The Series is explained here https://en.wikipedia.org/wiki/Fibonacci_number The pine cone's relation to all of the this is to do with the spirals. It is explained here https://realworldmathematics.wordpress.com/biology/plants/

Coanda Effect and the toilet at Watchtree Nature Reserve

The Coanda Effect is that a jet of fluid stays close to a convex or almost flat surface if it flows next to it due to pressure differences caused. In the case of this toilet, the set up means that a jet of urine stays close to the outside wall of the toilet and is separated from the solid waste, allowing the solid waste to be composted. There's an animated diagram at the bottom of this page http://natsol.co.uk/urine-diverting-compost-toilets/ This article on the Coanda Effect as applied to air flow suggests some experiments for me to try https://en.wikipedia.org/wiki/Coand%C4%83_effect

1 lux in the moonlight

Here's the full moon reflecting off a white wall. The camera is not as good a light collector as my eye. I could even see my shadow on the ground, which would not come out in a photograph. A full Moon on a clear night gives up to 1 lux. Further to yesterday's post about the perigee Moon looking bigger, I suppose the simplest thing to do with the apparent size is to square the angle subtended at the eye to give some sort of angular area subtended. At perigee that would be 9.59 milliradians to be squared giving 92.0. At apogee it would be 8.57 milliradians squared giving 73.4. The perigee Moon should look 92.0/73.4 = 1.25 x bigger or 25% bigger. I'm getting closer to the 30% figure commonly given.

Hunter's Moon and supermoon

The Moon was unearthly orange when we were driving home at 7pm last night so I looked to see if we were missing an eclipse. Articles called it a Hunter's Moon, though that seems to be a folklore name for a full Moon in October, perhaps when the poachers were out. It turns out it was also a supermoon. This is not a scientific term since it originated with an astrologer not an astronomer, The Moon does not go on a perfectly circular orbit around the Earth. It follows an ellipse. A supermoon is when it is at its nearest point, which is more accurately called the perigee. That's about 362600km away. By contrast, at its most distant or apogee, it is at about 405400km which is 12% further. They talk about how big the Moon looks. This will be connected to the angle subtended at your eye. In radians, that is the diameter of the Moon divided by the distance to the Moon. For perigee, the angle subtended is 0.00959 rad and for apogee its 0.00857 rad by doing the calculation using the radius of the Moon as 1738km. The apogee angle is 0.88 x the perigee angle so the perigee angle is 12% bigger. Squaring to give area would leave the Moon looking 23% bigger at perigee. I read figures that say 30%.

50 lux in the kitchen

I think the main kitchen lights are bright. I didn't need the flash on the camera to take this picture. But the solar powered flower toy wasn't working so the light intensity cannot have been high. Having posted about the lux light scale recently, I looked up the brightness of internal house lights - it's about 50 lux.

Ben Nevis caldera part 1

Last Christmas we went up Mount Teide on Tenerife. Many years ago, the then top of the volcano collapsed inwards creating a vast bowl, It's a pretty flat circle surrounded by cliffs. This is called a caldera.Then we went to Ben Nevis and found this:

So the same thing happened to Ben Nevis 410 million years ago. This is going to take some thinking about. But the view below must once have looked like the top picture from Tenerife!

Dutch wind farms

I took these pictures on the way into IJmuiden on the ferry from Newcastle. They are probably the Princess Amalia wind farm although there are two separate wind farms in that section. Princess Amalia has a name plate capacity of 120MW so it is not as big as Robin Rigg. I wasn't expecting that. I thought continental wind power would be bigger. Robin Rigg claims to supply 117,000 households. The population of Cumbria is 500,000 so that might well be half of Cumbria. This Dutch wind farm might do 100,000 households.

Robin Rigg wind farm

The offshore wind farm at Robin Rigg is a prominent feature in the view from north-west Cumbria. I've looked up its statistics https://en.wikipedia.org/wiki/List_of_offshore_wind_farms_in_the_United_Kingdom   180MW compares to a peak UK usage of about 50 000 MW so it provides less than 1% of peak power. It seems to be a medium-sized offshore wind farm - the ones near Barrow are much bigger in total. The West Duddon station provides twice the peak power but at four times the installation cost. But Wharrels Hill, the prominent wind farm near Bothel is only 10MW so this is huge!

Craters on the Moon

I decided it was time for me to stop ignoring the Moon. I never could get excited about the Moon when I was young but I have recently discovered that all of the features are named. This article explains who named the craters http://moonphases.info/how-the-lunar-craters-got-their-names.html Galileo coined the word "crater" from a Greek word for bowl because he was the first to see them as they are by looking at them through a telescope. I went out last night to take this photograph through my telescope. These northern craters were named by Giovanni Battista Riccioli a few years later after famous astronomers from the past. I'll have to find out what astronomy was done by Plato!

Youtube films I really like

Here they are again
Bohemian Gravity for string theory
https://www.google.co.uk/webhp?sourceid=chrome-instant&rlz=1C1EODB_enGB572GB574&ion=1&espv=2&ie=UTF-8#q=bohemian%20gravity

Smarter Every Day and Veritasium do the Coriolis Effect
http://www.smartereveryday.com/toiletswirl/

Spark counter for alpha radiation

It was out with the spark counter again. Nearly 3000V between the thin wires at the front and the backing plate. That is not quite enough for the air to conduct electricity. The alpha particles are helium nuclei so they have enough momentum to dislodge electrons from air atoms, turning them into ions. These charged particles can conduct electricity so you can see sparks when the alpha is present. It is ionising radiation.

D of E navigation nightmare

We were out with the Silver Duke of Edinburgh's Award walkers when we noticed this potential compass problem. If you hold the compass next to an iron gate, you can get the wrong direction for North. The compass needle is a magnet. It's magnetic field is strong enough to line up the domains in the iron, turning it into an induced magnet, which attracts the compass needle. Hence the needle will always point towards the gate - giving the wrong direction for North.

Ultrasound: mouse and rat repeller

I love the definition of ultrasound: any frequency above the highest that a human can hear. The highest we can hear is 20000Hz. This unit sweeps from 30000 up to 60000Hz. This is important because cats and dogs can hear up to 27000Hz so they are not distressed by the device. The garage is an ideal location for it because the hard wall surfaces reflect the sound round the space so one unit can cover the entire room.

How good is the night sky?

The square of Pegasus is a familiar landmark in the night sky at the moment, They say that you can judge how good the viewing conditions are by how many stars are visible in the square. I can see about half a dozen on a good night in Wigton. There is the added problem of how ours eyes work. They rod cells round the outside are better light detectors than the cone cells in the middle of the eye. So I can sense more stars inside the square but as soon as I look directly at them, the cone cells take over and the stars disappear because they are too dim to be detected by cone cells.

Lux in Wigton

We were intrigued by the name of the new tanning salon in Wigton. Lux is the SI unit for light received, as perceived by the human eye. It's a measure of the intensity of the light in Watts per square metre but factored to account for the fact that human eyes perceive some wavelengths as more intense than others. Hence the same Watts per square metre in yellow would have a higher value in lux than red. Now the name of the salon might be short for luxury but since sunlight for suntans could be measured in lux, I think it's an awesome name.

Winglets at Newcastle Airport

I noticed that our aeroplane had upturned wingtips. These are called winglets and are used to reduce the vortices that are formed at the tips of the wings. You can see these vortices in certain atmospheric conditions. There is a pressure difference between the air masses below and above the wing and this difference cause mini-hurricanes. Looking up this topic reveals the drag factors on aeroplanes to be very complicated so more research needed.