I discovered a hilariously wacky group on Telegram, “Rzhivopis.” I spent an hour on vacation using a script to download their paintings and overlay them with their custom titles from their channel. Then two more hours reviewing them all and picking out the best. Definitely subscribe, there are about 2000 paintings, I won’t post that many, but maybe next time there will be a second part of the funniest:)
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Driving in the old town is quite something
It’s interesting that even a little experience in drawing portraits makes one see patterns in other people’s faces that you wouldn’t think about otherwise. For example, you look at someone’s face, and some points on the face converge into an equilateral triangle. Or the shadow from the sun forms a notable pattern. Or some lines are strictly parallel or perpendicular. And at that moment, you feel like grabbing a pencil and trying to sketch it. At this point, it seems that achieving a likeness is a piece of cake.
Or you notice that a silvery dress is the darkest thing in the picture and probably needs to be depicted almost in black. With highlights, of course. This contradicts the notion that “a silvery dress is just a shiny white.”
Sometimes you look at someone’s face, reassured that the typical proportions are maintained, or, conversely, that they are not. There are also optical illusions. They are the most interesting. It’s when it seems that some point exactly divides a segment in half, but as soon as you measure, it turns out not to be the case.
It’s also interesting that our eyes deceive us about what lines are and what are not lines. Here, it would be more correct not to use the word line” but edge.”
What was the architect smoking?
I constantly see such panels on almost every house in Turkey. Of course, my first thought was that these were solar photovoltaic panels for generating electricity. But the second thought — they are expensive, there shouldn’t be so many of them, plus typically just two panels on a roof seems too few. I started googling.
It turned out, these are solar water heaters, more precisely, flat-plate solar collectors. The system is simple, reliable, and inexpensive — that’s why they are installed on every other house.
The principle of operation: the panels consist of an absorber (usually copper or aluminum plates with a black coating), a transparent cover (low-iron glass for greenhouse effect), and thermal insulation (glass wool or stone wool). A heat-carrying fluid circulates in the tubes — either water or antifreeze (glycol).
Solar rays heat the absorber up to 60-90°C, the heat transfers to the fluid, which by the principle of thermosiphon (natural convection, without a pump) rises to the tank, which is usually nearby. The tank is a thermos of 100-300 liters, with insulation, so the water stays hot for 2-3 days.
This too was a surprise. I actually thought the tanks were just metal and heated up in the sun by themselves. That’s how it was in Baku. It turns out, no, and so they are white here, not black.
In Turkey, with over 2000+ hours of sunshine a year, such a system covers 70-90% of the hot water needs for a home. The efficiency of the collector is 40-60% (depending on the model and angle of installation, optimally 30-45° to the horizon for the latitude of Antalya). For a family, this costs from 500-1500 euros, with a payback period of 3-5 years due to savings on gas/electricity. Electricity is expensive in Turkey. Plus, government subsidies and tax incentives encourage installation.
Probably, there are also electric panels, but I haven’t seen them yet.
I look from the boat at the water and wonder whether the divergence angle of the waves depends on speed or not? Started Googling. Turns out, according to Kelvin, it’s constant at any speed, and amounts to 39 degrees (or 19.47 =arcsin(1/3) from the axis). But then I found a paper where the authors studied satellite images and disproved Kelvin, stating that with increasing speed, the wedge indeed narrows slightly (“Ship wakes: Kelvin or Mach angle?”, authors: Marc Rabaud and Frédéric Moisy)
Came in to eat some sushi
It was supposed to be crab
Great idea indeed. A carriage drove past me, delivered a passenger, returns to base.
👀
