Liquid frost: the hyper-cold brine ponds of Sangiyn Dalai (1/3)

Intro: Freezing-point depression

This chapter will be a little different than the “classic exiles” as the research’s main target will be not air, but water and beside this the writing has a separate personal/ philosophical section. However the plan is strongly related to the local climate’s peculiarities, therefore worthy to include here as a new episode.

We know that water freezes at 0 degrees Celsius. In a practical approach a mixture of ice and water has always this same temperature, not influenced by the elevation (atmospheric pressure) as in the case of the water’s boiling point, which can decrease very much in the high mountains. This is valid for pure H2O, but if we dissolve some substances in the water (especially salts) the freezing point will start to decrease.

In the case of NaCl (rock salt) at maximum concentration (23.3%) this can go as low as -21.1 degrees Celsius. There are a few other salts (MgCl, CaCl), which can decrease the freezing point even farther. This is lab science, but how about nature?


The relation between the temperature and the salt content in the case of NaCl solution

Sea water contains around 3.5% salt and freezes at -2 degrees Celsius. The Arctic and Antarctic waters have this temperature under the ice. Are somewhere on the planet conditions so extreme to cool liquids to temperatures much lower than this?


Choosing the target

As you can conclude there are two terms, which are crucial here: 1. extremely salty water (brine), 2. severe cold. The combination of these two is mandatory.

Regarding nature/ climate, the first premise is mostly related to aridity, where the lack of rainfall and the strong evaporation will increase the salt content of the water bodies situated on the bottom of the closed basins and the second premise is about persistent seasonal cold, when these concentrated fluids are exposed to very low temperatures for a long time. Something like a crossing between the Dead Sea and Siberia? That’s right.

After a thorough pondering I’ve concluded that outside of Antarctica’s Dry Valleys (where this kind of environment has already been studied:, north-western Mongolia offer the best conditions for this phenomenon to happen.



Here are places which receive rainfall so low as Death Valley in the US, while at the same time have average winter temperatures similar with Central Siberia. Zavkhan sum of Uvs aimag is a good example for this combination of extremes, where the mean yearly precipitation is around 50-60 mm and the average January temperature is under -28 degrees Celsius.

Beside this, winter is the dry season, therefore snowfalls are quite rare and inconsistent here, with January and February averages under 1 mm and the snow thickness of the midwinter is usually between 0-5 cm. Locals refer to 4-5 cm as “big snow”.



Because of its dry climate the Great Lakes Basin of Western Mongolia has many salt lakes/ flats, which due to the higher mineral content, in the winter-time can cool down to much lower temperatures than the sea-water before freezing.

I chose the salt pan of Sangiyn Dalai lake in southern Uvs aimag (situated around 1030 meters above the sea level) to be my research area for this new purpose, where I suppose to have excellent chances to found liquids in natural context at extremely low temperatures.


The location of the Sangiyn Dalai salt pan on the map of Mongolia (red dot)

Brief summary of the research

I reached the salt flats on 9th of February and set my camp on its surface in the afternoon. I know this area for some time (I’ve been here more times in the past winters) and with the help of a detailed satellite image and GPS I identified many small and medium sized brine ponds/ lakes (1-20 meters in diameter) which can remain unfrozen at air temperatures lower than -30 degrees Celsius.


Satellite view of the lake and salt flats (brown part on the western shores)

This season is an average one, but now became colder as the daily maximum remained below -25 degrees and were good chances to have a night minimum of around -40. The sky is clear, the air is still. The typical thermal inversion of the mongolian winter. The snow cover in the area is around 3-4 cm thick and is only partial on the salty surface.


My tent in the salt desert

The particular lake I hoped to found unfrozen had now a layer of salty slush on its surface, hence the bottom pattern was not visible. The liquid’s temperature was close, but not below -20 degrees. Not far away I found a smaller one, which was only partially covered and was colder (below -20 near the surface).

Shortly after the tent was raised I discovered another lake, which was between the few still unfrozen water bodies seen by me on this day. But this one was more impressive than the others as it was significantly bigger (around 8-10 meters long) and surprisingly deep (around 2 meters) for its size.


The newly discovered unfrozen brine lake

The uppermost layer had a stunning temperature of -21, -22 degrees Celsius, but for my great amazement at the bottom it was above 0 degrees (+1.8 to be precise). This “warm” bottom cooled only very little even after the frosty -40 degrees night, the device shoved +1.2 degrees Celsius.

While there was a thin crust of salty ice on the surface of the lake, a small portion near the steepest side remained unfrozen. I concluded that this strange phenomenon must be caused by a strong spring under the salt bed.


Measuring the temperature of another pond . This is Fahrenheit scale, in Celsius it means -24.5 degrees

Even if the air temperature did not rise above -30 degrees Celsius, at midday the solid crust had transformed to a pasty slush. I collected half liters of brine from this lake with the purpose to found out the exact composition of the minerals (and maybe microorganisms) in the solution after returning home.


The coldest dive

As a “cold fanatic” I had a big dream for a long while, when I accidentally discovered the hyper-cold solutions near a former bay of Uvs lake: having the coldest bath ever taken by a human. This wish later transformed to “performing the coldest dive” as an even more complete form of the previous. And I want to do this unsupported, alone in the wilderness. After many years of planning, struggle and bad luck related to injuries and improper climatic conditions, on 10th of February 2019 shortly after midday the time has come.


After a -40 degree night even this special lake froze

This newly discovered lake has the size & shape ideal for my plan and the actual conditions were just on the limits of the coldest possible as most of the water body had some thin slush on its surface. I am here, physically, logistically and mentally prepared. Let’s do it.
I call this “The Convergence”.

After relocating the tent close to the lake’s shore and sorting everything to help me in this action, at 1:30 PM I was ready. Shorts, scuba gloves & socks, swimming goggles & cap. Just the minimal protection for this extreme environment. Most of my body will be in direct contact with the hyper-cold fluid. The temperature of the uppermost layer represented by the salty slush was around -22 degrees Celsius.

You have VERY short time here, no fumbling or bad calculation will be excused. The body looses heat 25-30 times faster in water than in air and at these freezing temperatures the solution can cause you frostbites in less than 30 seconds (!), much sooner than hypothermia can install, even before hyperventilation is over. And this is valid for any part of exposed skin. Frostbite is by far the biggest risk here. I know very well what this medium is capable of as it is not the first time I expose myself to these elements.


Traversing the hyper-cold lake

The dive went smooth. Good adherence on the margin, haven’t touched the bottom or the side with any body part, no brine entered inside the goggles and I managed to get out of the water in less than 15 (maybe 10) seconds.


Close-up of the thermometer: -7.3 degrees in Fahrenheit means -21.8 in Celsius (the sensor inside the brine slush)

Because of the speed I haven’t seen almost anything while underwater, reaching/ grabbing the other side and pulling my body out of this natural rapid-freezer in a single flow-like movement. The coldest sensation was just when I emerged/ left the water as then my entire body passed through the -20 degrees brine-slush layer. Probable the fastest cooling rate a human ever experienced.


The equipment used in the experiment

After out from the lake I knew the real danger was over. The tent was waiting for me with the strong greenhouse effect inside. The temperature difference between exterior and interior was certainly above 20 degrees Celsius in this part of the day.

I guess many people will think it’s still very dangerous when you are out wet at -30 degrees, but I can tell you from this and previous similar experiences that during midday sun and complete calm, for a few minutes you are safe, it’s almost “comfortable”. Of course, this feeling is enhanced by the adrenaline and endorphine rushes, preceded by massive dopamine ammounts and followed/ topped by serotonin release. A complex and thick biochemical cocktail. Genuine catharsis.


Mission complete

The instruments used in the field

-One LogTag Tred30-7R data logger with the measuring range between -40 and +99 degrees Celsius, an accuracy of 0.5 degrees Celsius and a resolution of 0.1 degrees Celsius.
-One Greisinger GMH 2710-T digital precision thermometer with the measuring range between -199.9, +200 degrees Celsius, an accuracy of +-0.1 degrees Celsius and a resolution of 0.1 degrees Celsius.


The LogTag data logger measuring the bottom temperature of the brine pond

To be continued…





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