Low clouds in climate models

These low clouds over Longsleddale are the opposite in climate models to the high clouds. They are thicker and the cloud tops reflect more solar radiation back out into space. However, global warming models suggest that a warmer earth will push clouds higher on average which will then increase the warming. See January 2025 Physics World for the details.

High clouds in climate models

There's a lovely article in the January 2025 edition of Physics World explaining the differing effects of clouds in climate models. High clouds are cooler being higher up in the atmosphere and absorb more of the outgoing radiation from the Earth's surface, reradiating a lot of it back down in the classic greenhouse warming effect that makes our planet habitable. These high clouds - like the alto-cumulus in the picture of Skeggles Water - are thinner so they also let more sunlight through which is another warming effect.

Venus

Venus has been very prominent in the early evening these last couple of months. It was the subject of a feature in the last series by Brian Cox on the Solar System. I was interested in the apparent "snow line" effect on the mountains of Venus. It's a kind of metallic frost. It has to be something that melts and evaporates at 460 Celsius at the lowest levels on Venus but solidifies at cooler temperatures with altitude. Brian Cox names lead sulfide as a possible candidate. Looking that up, I see a melting point of over 1000 Celsius. This must be at Earth's standard atmospheric pressure and will be different on Venus. This article names bismuth sulfide and tellurium as other possible candidates.

Retrograde motion

Mars has been in retrograde motion recently as Earth has been overtaking it. Earth has a higher angular velocity. Mars is still going forward but looks like it is going backwards relative to a fixed reference point. OK, there are no fixed reference points in space but the background of stars are so far away that it doesn't make much difference. Here Mrs B was overtaking a lorry coming up to a bridge. Above, the cab lines up with a bridge in the distance. 

In the second view there is daylight between the cab and the bridge and below the cab is nowhere near lining up with the bridge. You could achieve the same effect if we were still and the lorry went backwards. But all the while it was moving forward at 50mph. This is what we mean by retrograde motion.

Polarised ice

Stress colours in ice above Kentmere through polarising filter. And then rotated through 90 degrees

The cracking seems to have contributed to the stress. Concentric so perhaps shrinkage on freezing? 

Mars in Opposition

Mars is clearly visible in our eastern sky early evening at the moment. I have heard that Mars is in opposition at the moment. That means that it is directly on the opposite side of the Earth to the Sun. So Sun, Earth and Moon form a line.

Mars takes almost twice as long as Earth to go round the Sun so I'm going to approximate to a two year orbital period. In 6 months, Earth has gone half way round the Sun but Mars has only gone quarter of the way.

In a year's time, Mars will be on the opposite side of the Sun to Earth.

And in 18 months we still won't have caught it up. So it will be almost 2 years until the next opposition.

Statistical Physics and Sheep

There's a lovely article in Physics World magazine from November 2024 about efforts to model the herding behaviour of sheep. It says that the original work on flocking was done modelling birds by having them match the speed and direction of those nearest whilst inserting a repulsive force to avoid collisions. Sheep proved more problematic because flocks don't just do one thing. There is a need to have both an eating in one place and a moving to a different place behaviour. This is seen as being like a phase transition. Sheep have a hierarchy so some animals lead and the rest follow. That also needs programming into the model. So I'll be keeping an eye on the field!

Salt on our windows from Storm Eowyn

Storm Eowyn has picked up salt from the sea and perhaps dust too and deposited a layer over our windows and car. The sea is a good dozen miles away. Turns out this is just like the Saharan dust that we get occasionally.

This Is A Low: Storm Eowyn

I posted about bombogenesis when Storm Ashley hit. This is a fall of 0.71" in 24 hours. Yesterday afternoon at 4pm my barometer read 29.4". Now it is 28.7" which is a lot lower than Storm Ashley. This must be bombogenesis.

Thirlmere Aqueduct again

We crossed the Thirlmere Aqueduct again near Staveley on the Potter Fell walk. It is disguised as a bridge by the Victorian ironworks were a give away. The pipes are high above the beck below. I dropped a stone and timed 1.90s. I'm not sure the stone fell cleanly, so let's say 1.5s. Using s=1/2gt^2 gives a height of 11m. It's probably a little under 10m but not much.

Block of ice

We found a huge block of ice in a water tank above English Kershope. Its depth was the bottom section of the pole so 27cm. The width is about 90cm and I estimate the length at 150cm. Volume is 364500 cubic cm or 0.36 cubic metres because 2sf is the best I can claim. Density of ice depends on temperature but at 0 oC it is 916 kg/m^3. So the mass of the block is about 300kg. Specific latent heat of fusion of ice is 336kJ/kg so it would need over 100000kJ to turn the block into water at zero Celsius and that is ignoring any energy needed to raise the temperature of the ice to zero Celsius.

Gravity gate

This gate at Mirehouse has a brilliant self-closing mechanism. You push the gate and it forces a wheel upwards along a curved track. You are pushing uphill against gravity. When you let go, gravity pulls the gate back down the track provided the oil is oiled. 

Radon Gas

I was interested that radon gas had been detected in a building on the Chastleton estate. A quick check of the UK radon map shows that this is a radon area. This site explains that limestone can also be a problem geology. This explains why it is the daughter decay products that are the lung cancer danger. 

Does sea ice contain salt?

At Port Carlisle, there is ice banked up on the beach. This will be from the sea freezing in the shallows at high tide in the night. It has a very funny texture and freezes in odd shapes. Some of the sections are reminiscent of the bigger, harder mini-ice-bergs that washed up in 2010. We wondered if the freezing process removed the salt. One small piece sampled had no salt taste. This article explains our observations quite well. It is probable that we had the start of pancake ice. It also explains the mushy texture. I have seen articles that say sea ice is salty but in less than 4 years it becomes pure H2O. The Met Office article would suggest that the salt gets concentrated into tiny sections. How the salt is then removed over time is not clear to me yet.

House on the Bridge

This set up was needed to create a platform to repair the House on the Bridge in Ambleside. It is a hinged platform so we can apply moments. I estimate that it is 6m long. 8 x 20kg masses on the pavement. Two attachment points on the platform make the analysis more complicated and perhaps unsolvable so I'm going to assume that all of the load goes through the oblique cable at about 30 degrees to the platform. Worker at 3m from hinge, cable at 5m from hinge. Then moments 

5W=3 x 160gcos60

W = 1300N

So it will support a worker but not much more because the weight of the platform is included.

The Albedo of Snow

This week the snow on the fells has been so beautiful against the clear blue sky. The snowy peaks seem to shine. This is because snow reflects most of the light that shines on it. I have read that this is because the snowflakes are tiny flat planes. They are all oriented in different directions so that the reflection is diffuse. Swiss avalanche researchers give the albedo as up to 95%.

APOD jigsaw

 We were intrigued by a link on NASA's Astronomy Picture of the Day for 6th January 2025. It takes you to a page that offers an online jigsaw of the image. We managed the one with the biggest pieces. Thanks to Mrs B for spotting this one.

The potato radius

This came up in the last Brian Cox series on the BBC, Solar System. Asteroids are large lumps of rock in all shapes but often looking rather like a potato, with one axis larger than the other. When rocky objects get to a certain size, they have so much mass that gravitational forces can pull inwards enough to make the rocky object spherical. Then we can call it a Dwarf Planet. The Potato Radius is the smallest radius of such a dwarf planet. It is somewhere between 200 and 300km.

Storage Batteries for Solar

 

Having worked out in a post the other day that I could perhaps generate 5000kWh of solar a year, could I use that? My total energy consumption for a year is bang on average at 11500kWh so it would be nearly half my annual consumption. Batteries are now being touted as a way to smooth out the electrical use. On a summer day I might generate 20kWh but I only use 5kWh. The smallest battery at 5kWh would be no use because I'd be needing to store more than that every day. Even 150kWh battery would be storing 10 days of surplus. I don't think this advert is aimed at me.

Albedo and drying roads

There was plenty of snow here yesterday and slush on some roads out of town even this morning which could have caused problems with a forecast of freezing temperatures.

But where the dark colour of the roads has been exposed, thermal energy is more easily absorbed. We say that the road has a low albedo because it is a good absorber. The thermal energy helps to evaporate the standing water, drying the roads and hopefully keeping us free from ice in the coming freeze.

Data about Solar Panels

 

This article from the Oxford Mail gives some useful figures about solar panel output. 1400 square metres is giving 260,000kWh per year. My south-facing roof is maybe 30 square metres and further north so might give 5000kWh per year.