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

Conclusions regarding the brine ponds

After returning home I correlated the new discoveries with my previous observations on the salt flat. I had some presumptions even before, but now I realized the big picture. Let’s analyze the puzzle in parts:

Case 1:

When I first visited the area in January 2011 I found a decent sized pond, which I observed/ selected beforehand using a detailed satellite image. The imagery’s date is 2010 May 27, so it was less than a year old, when I went there. The circular lake I found was more than 10 meters in diameter and (as it was only partially frozen) I estimated the maximum depth to be more than 2 meters. The temperature of the upper layer was -21 degrees Celsius. I returned here about 10 days later and found the pond frozen, except a small portion near one shore, where I measured -22 degrees Celsius close to the surface.

One of the biggest brine ponds of the salt flat, now inexistent (January 2011)

Next winter, In January 2012 I revisited this place and found this lake completely frozen, covered with a thick layer of salty ice. The ice was so massive I could safely walk on it and dig holes on its surface to study the brine beneath. The temperature under the ice was -23 degrees Celsius. This was an expected value as the solution beneath the ice became even more dense, conversely has even lower freezing point than before. But I was a little surprised to not found a single place where the depth exceeded 130-140 cm. I thought maybe it’s caused by more salt deposition on the bottom as the brine became even more denser during the freezing-point depression.

This particular pond wasn’t visited in the following years, I returned here only this winter, in February 2019. There was no lake, not even a shallow, frozen one. I rechecked the coordinates in my GPS at home and correlated with the imagery, but it was no doubt: that water body disappeared.

Case 2:

In January 2014 I was back to the salt flats. This time I accidentally discovered a new lake, which I recognized to be one of the bigger ponds visible on the same 2010 May 27 imagery. The 8 meter diameter circular pond was unfrozen and I measured below -23 degrees Celsius close to the surface. The shores were steep, the bottom at the deepest portion wasn’t clear because of the considerable depth, which was probable more than 2 meters.

This lake still exist, but now is less deep (February 2019)

In February 2016 I returned to see this lake. This was an exceptionally cold winter with -46 degrees recorded at Zavkhan weather station at the end of January. The lake was now covered with a thick layer of salty slush, but its temperature was only -18 degrees Celsius, a few degrees warmer than before, unfrozen. Maybe because of the changing in the surface layer’s composition? Or because of the higher solar angle in late February? Not sure. I checked the depth of the lake using the poles of my tent and found out that the ground was very uneven on the bottom. In some places it was 1.5 m, in others (just a little farther) less than 1 m. But far from 2 meters at any point.

Case 3:

In January 2014 I searched for eutectic frozen brine, so I was looking for very shallow ponds. However I was surprised not to found a deeper lake in one particular area, as I remembered from the imagery there is one. There were some shallow frozen ponds, but none of them had considerable depth (less than 0.5 meters) as I was expecting.

The newly found lake is situated in an area, where on the old imagery are visible some water bodies of variable depths, but this one wasn’t there in 2010

This winter, in February 2019 I discovered this new, 2 meters deep brine lake (where I’ve accomplished the dive), which I thought to be the one I couldn’t found in 2014. But after analyzing the exact coordinates I figured out that this lake is not exactly on the same place, where the deeper pond on the imagery appears. Also the shape is different. And the deeper pond (according to the imagery) is no longer there. This lake has the slush temperature of around -22 degrees Celsius, with the incredible bottom temperature of +2 degrees. As this sensor with the 3 m long cable is a new one, I have no infos regarding the bottom temperature of the other ponds in the former research years, but I suppose, that in the case of the deeper ones, the stratification can be similar.

Case 4:

This winter, in February 2019 I discovered this partially unfrozen, new pond of around 4 meters in diameter, with the surface temperature of -24 degrees Celsius. After returning home I found out that at those coordinates there is no lake on the 2010 imagery, not even a tiny one. The imagery has a 0.5 meters resolution, so even smaller features are identifiable (like camels or bovines). It’s clear: on that date this pond didn’t existed.

Taking into account the above mentioned facts, regarding the geomorphological/ hydrological aspect my major conclusion is that the lifespan of these brine ponds is small (usually less than a decade), they are constantly forming by the action of the springs under the salt crust (underground erosion/ dissolution) and disappearing by the formation of new salt deposits on the bottom of the water bodies (colmatation with evaporites).

The aerial view of a part of the salt pan from 2010 May 27: black arrow pointing to “Case 1 pond”, yellow arrow to “Case 2 pond”, teal arrow to “Case 3 pond”, red arrow (+ sign) to “Case 4 pond” (coordinates of this point) and the blue triangle is the location of my tent in 2019 **Zoom in for a better view**

Regarding the water temperatures my observation is that the surface layer generally reaches the slush state between -20 and -25 degrees Celsius, in most cases around -21, -22 degrees. There are some smaller ponds, where I saw liquids even close to -29 degrees Celsius. As the water bodies are not far from each other (sometimes it’s only a few meters between them), I consider that the general ratio between the solution’s components must be (almost) the same and these fluctuations between the freezing points are mainly caused by general concentration and not ratio changes between the constituents.

Another thing I could mention is that when the surface layer reaches the slush state at a certain temperature, the deeper layers must have an even lower freezing point as in the case of salt water the density rises constantly with the temperature decrease, so if the deeper, unfrozen layer is still heavier than the upper one, its freezing point is certainly lower. This also means that the surface layer’s slush can never reach the maximum possible concentration of the solution.

Note: After I get the water sample analysis results from Budapest (hopefully soon) I will update this section.

Liquid frost: the hyper-cold brine ponds of Sangiyn Dalai (2/3)

Journey photo album

Ulaanbaatar. Tsagaan Sar (Mongolian Lunar New Year) with my guide, Gansukh’s family

The center of Khovd, capital of the aimag with the same name and also of entire Western Mongolia

Street in Khovd with Ulaan Uul (Red Mountain) in the background

Mosque in the town. A significant kazakh minority lives in the town, who are muslims

On the way to Sangiyn Dalai. Somewhere near Khar Us lake’s shore

After crossing the barren plateau between the basins of Khar Us and Khyargas lakes we approached the target, deviating from the Zavkhan road using the GPS (around 130-140 km’s from Khovd). The weather is excellent on the salt flats: sunny, cold and no wind. I am in time to explore a little and raise my tent before sunset

This nice lake was my biggest hope to found unfrozen brine with decent size, but now it was covered by a thick slush layer. I know this jewel from previous trips and saw it unfrozen at -23 degrees Celsius (!). Now the slush is above -20, maybe the last snowy days diluted a little the surface layer’s composition

A little farther I observed a smaller pond, which was only partially covered, with the salt formations on the bottom visible. This is what I am looking for. The temperature of the uppermost layer is below -20. Great

I found a good place for the tent on a slightly convex portion. For my surprise I can even secure it as the salty ground was just perfect (not too soft, not too hard) at these low temperatures

Just before sunset, after only a few minutes walk from my tent: What the heck is this? Oh yeah, it’s unfrozen!

And it’s VERY deep! At least 1.5, but rather 2 meters! Astonished to found this outstanding water body here. A really pleasant gift for the end of the day. Hmmm… Yep, I can do it. I felt huge amounts of dopamine invading my body

On the surface it was around -20 degrees Celsius, but for my big surprise the sensor set on the bottom showed +1.8 degrees! As outside air temperature was below -25, this is really weird. I don’t believe, that the solar radiation can cause this, it’s more likely caused by a strong spring under the salt bed. I will let the sensor here during the night to observe the fluctuation. Unfortunately this logger is said to work only above -30 degrees, so I have little chances to monitor the entire night. Certainly will be below -35

As I expected, a very cold night was waiting for me. One of the coldest I ever spent in tent. You need to be prepared here, no chances to survive without the proper equipment

This is outside near surface temperature beside the tent. I haven’t observed the conversion to Fahrenheit scale as at -40 the two are exactly the same. Probably I pressed some combinations of buttons, which caused this change

During the severely cold night even this special lake froze. Except for a small portion near the steepest side, the brine pond was covered with a thin crust (around 0.5 cm) of salty ice. Bad news for me: looks like my big plan can’t be realized… Then again, despite the extreme conditions the logger was constantly recording. The bottom of the pond cooled only very little from yesterday afternoon as the device showed +1.2 degrees in the morning

Even though, I have a lot to do here as the entire ecosystem is extraordinary. This dark colored salt crust can melt the snow cover even below -30 degrees. No other dry surface is capable of this

This matte-white substance is completely frozen brine, an eutectic mixture of pure salt and ice. Very shallow ponds can reach this state during exceptionally cold nights, like the previous one

A quite dangerous place to walk around as sometimes the salt crust is very thin and it can break under your weight

Measuring the temperature of a pond. Meanwhile I realized the Celsius to Fahrenheit scale change, but (as I never done it before) couldn’t figure out the button combination necessary for this action and left it like this. As a matter of fact my purpose was to explore/ monitor liquids with negative temperatures not only in Celsius (which can be attained even in the case of sea water), but also in Fahrenheit scale, which means below -17.8 degrees Celsius. Therefore this unexpected joke of the fate wasn’t really a problem for me

In many parts the salty surface reminds me of the spiky skin of the moloch, a weird australian reptile

There are also very tiny ponds, like small holes in the salt crust

Around noon I found the big pond unfrozen again. Even if the air temperature didn’t rise above -30 degrees, under the midday sun the hard crust of the morning has transformed into a thin layer of slush. No words. It’s dream-like. After all I can do The Dive (details in part 1). Note: This picture was made by the “self-timer/10 seconds” function of the camera, using the tripod

After the experiment: the equipment on the lake’s shore

The unperturbed midday sun and complete calm helped me to accomplish this performance safe at -30 degrees air temperature

Standing on the place from where I’ve done the plunge

Mission complete. Time to leave, the driver will come after me soon

The Seeriyn Nuuryn Ulaan range in the distance

This part is a little saggy. Not dangerous, but you can’t cross it without mocking your boots

Camels grazing not far from the salt flats. I saw them every year in this grassy area

Still no wind, hence I feel comfortable moderately clad below -25 degrees. But the hoarfrost don’t lie

Ganbold and his UAZ. This russian 4wd car is still common in Western Mongolia, but in the central and eastern part of the country the new korean and japanese jeeps have mostly displaced them. However the driver told me that those are not really good in the winter as diesel fuel is more sensitive to the extreme cold

Following our track on the way back to the road

This is the “main road” between Khovd town and Zavkhan sum. We haven’t seen a single car for about two hours

He is an experienced driver, which is a must in this harsh wilderness. Mongolian drivers are also good mechanics. The two profession is one single here. You must be able to repair your car if needed as localities/ car services are very far from each other

The final section on the new chinese-built asphalt road

Two days later I visited Khovd museum. Snow leopard skin and ibex. The former prey on the latter

Ibex and argali (Marco Polo sheep) horns. Both animals are very large and robust, considerable bigger than their european cousins

Stone heads of turkic origin. Before the mongols this region was ruled by turkic tribes. Kazakhs are also part of them and in the Altai mountains (especially in Bayan Ölgiy province) they are still the majority

More mongolian ethnic groups are living in Khovd province. Each one has his own specific clothing

Religious artifacts. Buddhism is the dominant religion of the country

After two days rest in Khovd we start the trip to the Altai Mountains, my second target. Herds of mixed sheep & goat are very common in Mongolia

Crossing Khashaat pass (2550 meters) on the border of Khovd and Bayan Ölgiy provinces. From now on we are on kazakh land

Tsast Uul (around 4200 meters) the highest peak of the Tsambagarav range is in front of us. Now we are heading to visit a kazakh family who are hunting with eagles, but tomorrow I will return to the mountain

Nice weather and is likely to be the same in the following days. The previous night was cloudy, the ground is covered with a thin layer of fresh snow

Lonely tree near a frozen river. There were no others even in the bigger surroundings

This can happen here at any time, but Ganbold knows his profession

Meanwhile the mighty Tsast Uul is watching us

Approaching Altantsögts, the village where the “eagle family” lives

After lunch we are heading to the nearby hills to hunt with the eagle. My host is the multiple national champion of the “eagle festival” held every year in Ulaanbaatar and also in other locations outside Mongolia

“Kran” is the kazakh name for eagle. They are trained to hunt foxes, rabbits, even wolves. This is an important local tradition

“Hmmm, what can I eat here? I can see only sheeps and goats…”

We move to another location. The master’s son is handling the big bird

I observe on a neighboring ledge another “eagle man” on horseback

“I’m too hungry, can’t wait more. I will eat this rival!”

Nope. We are friends and will continue the hunt together

As no wild meet is available, we are playing with what we have

Ganbold is not big a fan of hiking. At least not by foot 😉

Tsast Uul in the distance. We will meet tomorrow

For a lil’ while I became a kazakh. Or it’s maybe more? Many people say hungarians are related to kazakhs

Kran serving dinner. Our meal was also lots of meat, traditional kazakh style. They eat even the eye of the sheep (I admit I skipped that one). No place for vegans here

Next morning we start the way to the mountain

The night was starry, but now the clouds are invading the sky. The top of Tsambagarav is covered by altocumulus lenticularis

Stopping/ eating in an isolated mongol yurt. As I understood, kazakh yurts are bigger, hence more difficult to keep it warm during winters. Therefore kazakhs are living in houses in the cold season

This doesn’t looks very good. The forecast showed only partially cloudy for today

We reached close to 2500 meters elevation and soon I started the ascent. It’s noon now. My plan for today is to set my camp a little higher and do an acclimatization trip to 3000-3500 meters

The tent was raised at 2700 meters elevation. It wasn’t easy. No strong wind, but those frozen rocks…

The weather worsened as I climbed higher. The wind intensified and snow started to fall. Anyhow I reached above 3500 meters, that’s enough for today

Back to the camp. In the late afternoon the weather conditions improved and the night was completely starry. It was much more comfortable in the tent than at Sangiyn Dalai as it was about 10 degrees warmer. So I rested pretty well

As I expected (and hoped) the next morning the weather was good. I started the climb in dark. Temperatures in the -20s, but the windchill was quite strong. On the surface certainly was colder as my feet felt it soon. On the mountain, because of the steep terrain you are more predisposed to frostbites as the contact with the solid surface is much longer than when you walk on flat terrain. Altitude also worsens this

Nice sunrise, but not (yet) for me. Since I climb from the west I am in the shadow of the mountain

Reaching a flatter portion above 3600 meters elevation. Now I can see what is waiting for me in the final part. More than I thought

Traversing an exposed, edgy section with some easy technical parts. No need for the crampons until now. The snow is small and has good consistence, the wind is mild to moderate

Finally, somewhere above 3800 meters the Sun found me. Or I found him. I climbed constantly for more than 3 hours, it’s time to eat something. That something is goji berries & pecan nuts

The steep rocky part soon is over. I feel the altitude. No sickness, but I’m sluggish

Definitely crampons time. At around 4000 meters

After 5 hours of strenuous effort from the camp I reached the top of Tsast Uul. The GPS shows between 4200-4210 meters. On the maps usually appears with 4193 m, so it’s pretty close. Ganbold told me no climbers are going to Tsambagarav in the winter, not even mongolians. Instead in the summer many, including westerners

The top is very flat, more like a plateau

A zoom to the west: many other high peaks of the Mongol Altai

Now it’s almost noon, the temperature (still in Fahrenheit) is only slightly colder than my bath in Zavkhan sum (-22.3 in Celsius). Of course this is not a correct measurement, but when it’s windy solar radiation has little effect on the sensor

There are some hidden crevasses under the snow on the ice cap. This hole was made by me, involuntary of course. Fortunately I had the luck and strength to pull myself out before disappearing completely. The driver told me that Khüiten Uul’s Potanin glacier is extremely dangerous because of these formations and according to his knowledge it was a single mongolian climber who reached the top of the 4374 meters peak (highest in Mongolia) in the winter, but he died on the descent

I will follow the same way back. When it’s steep on the ice is safer to step backwards

It’s warmer and the wind is light. The hard part is over. I forgot a thermos somewhere during the ascent, but I will recover it following my trails. Otherwise soon it will be tough for my kidneys…

On the last part the weather became really warm as the wind stopped completely and the early afternoon sun was doing his best. At a certain time I felt comfortable in a single blouse. Incredible how much difference between the windy morning and this abundance of radiation. Only rocks. Pretty tiring as the snow is small and your feet are constantly unstable on the steep slope

I saw the driver’s car coming while descending the mountain. He arrived much sooner this time, maybe he was a little worried. I packed everything in time (also have found the lost thermos) and started the last, easy part back to the meeting point

I’m okay, he’s okay, Khovd is waiting for us

Because of the snow drifts we must found another way through the rocks. It was on the limits, the car almost crashed at a certain point. Thanks to the drivers experience we managed to get out from the labyrinth

Back to the asphalt we stopped to eat beside the road, then helped another guy to start his frozen diesel engine. Here people always help each other as they know very well what it means to be blocked in the middle of nowhere

My hotel room in Khovd. See the picture? Its Tsambagarav

Giant mongolian boot (gutul) in the center of the town. Its match is on the other side of the road

Next day I go to a hike to Ulaan Uul sandstone mountain in the vicinity of the town. Frosty morning in Khovd. And back to Celsius 🙂

He has the teeth, I have the ice axe. But the contact remained only verbal

It’s colder than on the mountain. But without the windchill is not that bad

After about 10 km’s on the road I turned to the right and started to climb the mountain from the back side. Because of the new snow layer now is dangerous to try the rocky front side

Following goat trails between the sandstone boulders

On the top is much warmer and there is still no wind. The thermal inversion is very strong

Khovd in the mist. You can see the runway beside

Descending on the same side. From the road I hitchhiked and reached the town by car. The traffic is rare, but the few cars will certainly stop for you. Often without waving

Restaurant in Khovd. Today is Sunday, many of them is closed, including this one. I can’t order my favorite soup…

Approaching Ulaanbaatar. This winter is completely free of snow in the capital

The Government Palace on the Chinggis Square

The Giant Buddha statue of the Gandan monastery

Turquoise reflections on the streets of Ulaanbaatar. It’s almost spring here

Stone caravan on the way to the airport. I will certainly return here

To be continued…

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: https://en.wikipedia.org/wiki/Don_Juan_Pond), 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.

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.

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.

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.

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…