Articles about the manufacture and use of home weather stations are published regularly on Giktime. I decided to keep up with the trend and also write a story about the weather station that hangs outside my window - about the stormglass.
In short, a stormglass is a flask with a camphor solution used to monitor the weather in the 19th century. There is a lot of information on the network about him - but the descriptions of the principle of work are usually reduced to the esoteric "did not receive a full scientific explanation." Several years ago I read about stormglass, got interested, made one for myself, experimented at home for several days, then hung the bottle outside the window and for the second year I have been observing its behavior in real conditions.
The explanation of the principle of operation turned out to be incredibly simple, and the device itself was sensitive enough so that, by looking at it, I could understand how to dress when leaving the house.
Stormglass is known largely thanks to Captain Fitzroy, the same one who took Darwin on a trip around the world. In a nutshell, stormglass is a solution of camphor in diluted alcohol, with the addition of inorganic salts. The solution is unstable, and when the weather conditions change, camphor crystals fall out of it, the quantity and shape of which can be used to judge the weather.
I did not find clear explanations of the principle of operation of the stormglass on the Internet, but, in general, it was clear that the main "operating factors" of the weather were temperature, pressure, humidity, insolation, and also, possibly, something like an electromagnetic field. It is known that in old weather stations, storm glasses were usually sealed flasks, which means that they could not measure pressure and humidity. In the visible part of the spectrum, the stormglass solution is transparent, and the glass bulb does not transmit ultraviolet light well, so a reaction to sunlight is also unlikely. It was more difficult to exclude the influence of electromagnetic fields or factors unknown to science on the solution - but, nevertheless, it seemed to me the most probable that the stormglass reacts to temperature fluctuations.
My stormglass shows that it is now cool and gradually getting colder.
I thought about all this even before the manufacture of my bottle. The very first experiments showed that I was right. The fact is that the solubility of camphor in a mixture of alcohol and water strongly depends on the temperature: it is enough to slightly warm the solution, and it becomes transparent, it is enough to cool it - and the whole flask will be filled with white flakes of camphor. At the same time, the principle by which the composition of the solution was selected became clear: the ratio of the amounts of alcohol and water was taken such that in warm weather most of the camphor would dissolve, and in cold weather it would precipitate; then, with a change in temperature, the amount of camphor flakes will change most noticeably. Mineral salts are needed in order to increase the density of the solution; due to the addition of these salts, the density of the solution is approximately the same,as the density of the dropped out camphor crystals - that is, crystals growing in the thickness of the solution will not sink, and they will be seen best.
These were common words. Now some observations:
Promotional video:
- The most obvious fact: the amount of crystalline camphor at the bottom of the bottle depends on the temperature. The colder, the thicker the layer. At the same time, over time, the deposited layer becomes denser, therefore the dense layer at the bottom shows the approximate temperature of the last weeks, and from the change in the thickness of the loose fresh layer, it is easy to estimate how much colder it is today than this average level.
- With a slow cooling, needle-shaped crystals begin to grow at the bottom of the bottle. On the contrary, with warming, the needles of crystals dissolve, and the bottom layer looks like loose melting snow.
Slow cooling: clear solution and camphor needles. The smaller the needles and the longer they are, the slower the temperature dropped. Remember the first batch-produced stormglass photo? There the needles are very long and beautiful - apparently, the stormglass was cooled very slowly and carefully - perhaps even in a thermostat.
With a faster cooling, camphor crystals precipitate not only at the bottom, but throughout the entire volume of the flask - they look like snowflakes soaring in the thickness
- Moderately fast cooling - snowing.
- And when it gets colder very quickly, even snowflakes do not have time to grow, the entire solution becomes cloudy at once and becomes similar to Schweppes.
Schweppes. The solution in stormglass is cloudy - this is how it looks during a sharp cold snap; at the bottom lies a yellowish layer of caked camphor; This layer is thin, that is, it is now warm enough.
The question arose: "How is the crystal size related to the rate of temperature change?"
Of course, for a full-fledged weather prediction, one observation of temperature dynamics is not enough - in fact, even modern meteorologists, who have powerful computers and a network of meteorological stations that enmeshed the entire planet, are not very good at this task. But in the conditions of the beginning of the 19th century, when even the most banal thermograph seemed to be a high-tech device - and in sea conditions, when the thermograph had to be somehow protected from ship rolling - the functions of the stormglass turned out to be in demand.
Now a little about the manufacture of stormglass:
Potassium nitrate and ammonia are potassium nitrate and ammonium chloride, respectively, and can be purchased at a hardware store. A 10% camphor solution is sold at the pharmacy.
The concentration of camphor is not too fundamental - I read about stormglass made directly from a pharmacy 10% solution. But, if you (like me) do not want to deviate too far from the recipe, add water to the pharmacy camphor solution - camphor will immediately precipitate in the form of large dense flakes that are easy to filter (for example, with a non-woven cloth), dry (note that camphor evaporates during drying, and you need to take it with a margin) and dissolve in alcohol again, to the desired concentration.
If you got the salts from the hardware store, they are most likely dirty and should be recrystallized. This is also simple: take boiling water (preferably distilled water from an auto parts store), pour so much salt into it so that it stops dissolving, defend the solution (or rather filter it through the same non-woven cloth), cool it to room temperature, collect the bottom sediment of salts and also dry it.
Now you mix the components in the right proportion, and you get a conditionally working stormglass.
Another stormglass with beautiful crystals. If yours is standing in the room, and not hanging outside the window, then something similar may grow in it.
"Conditional" - because it also needs to be calibrated for your weather. It's a bit boring, but also easy: take the resulting mixture, slowly heat it to the temperature you want to make the maximum working temperature - for example, to the temperature that the thermometer hanging outside your window shows on a moderately hot summer day. Now make sure that very little camphor remains at the bottom of the container with the mixture: if all the camphor has dissolved, add water dropwise to the solution with constant stirring - until a little sediment appears at the bottom; keep in mind that the precipitate will fall out with every drop, but until a certain moment it will dissolve with stirring. If there is too much sediment, on the contrary, add alcohol.
Probably, you can also calibrate the solution in terms of density, but a small deviation of the density from the required one has little effect on the operation of the stormglass, so I did without this stage.
All! The solution is ready! Pour it into a bottle with a ground stopper (leave a little air in the bottle so that the solution can expand when heated), seal it with a sealant (I recommend taking a silicone solution - the solution is quite active, and, for example, the vacuum grease, for example, dissolved in my place in a year, also turned yellow, in result), hang it outside the window next to the thermometer - and watch the growing and dissolving crystals.
Author: APLe