Island continent
An Antarctic Mystery: Physical Spectacles of the Frozen Continent
The poles experience polar summers and winters, two extraordinary phenomena occurring nowhere else in the world. During polar summers, the Sun never sets, so it is full time “day”. During polar winters, the Sun never rises; it is the darkness that prevails for many months. Antarctica is the most inhospitable continent on Earth; it is the coldest, driest and windiest. Antarctica is considered the largest desert in the world. Island continent
An Antarctic Mystery is a famous two volume novel by the French writer Jules Verne, written in 1897. Depicting the nautical adventure to Kerguelen Islands, southern Indian Ocean, I had read this book during my school days. This novel implanted a subconscious seed within me, to long for a long and adventurous voyage to Antarctica. I was fortunate to be part of 36th Indian Scientific Expedition to Antarctica (ISEA) and I visited both the Indian research Stations in Antarctica, ‘Bharati’ and ‘Maitri’, aboard m/v Ivan Papanin – an eventful expedition lasting four-months in early 2017. While An Antarctic Mystery is a work of fiction, this article is not; it narrates a number of bizarre physical phenomena, optical illusions, eerie geographical features and much more that one can experience in Antarctica. Island continent
We left the Port of Cape Town, South Africa on 27 December 2016, and in next one week’s time, we progressively headed south by crossing the celebrated southern latitudes, roaring forties (40°S), furious fifties (50°S) and screaming sixties (60°S)− the de facto boundary of Antarctica. By then, we could see numerous small blocks of the floes − floating masses of ice pieces in various shapes− all around the ocean. The temperature of surface water measured, to my surprise, minus 1.8°C. Salt in the seawater brings down the freezing point to minus 2.8°C (the same reason many cities in the higher latitudes sprinkle salt on the roads during winter to melt the fallen snow), an immensely cold water indeed. Man overboard (a person falling to sea from the ship) in these waters would mean instant death from hypothermic shock and cardiac arrest, no matter whether he is wearing a life jacket or not. We approached the continent on southeast direction and could increasingly spot icebergs − a few enormous ones too, especially on our starboard side (right side of the ship). The size of floes progressively got larger, and the sound of these floes hitting on the hull of our ship produced a distinct loud “bang” on iron, a sound remarkably similar to those in war zones depicted in World War movies.
As we crossed the Antarctic Circle (66.5°S), the floes were replaced by drift ice, also known as pack ice− a contiguous layer of white, floating and mobile ice sheet on the sea surface. The thickness of this ice sheet was quite small at first, about a metre, which increased as we approached the continent. The sight of our ship moving through this pack ice was quite remarkable; almost every one of us was gathering either at the bow or the terrace above the bridge, relishing the scene, and capturing it with our cameras. As the hull hit these ice sheets, cracks would appear on the sheet at random locations; not exactly at the point of collision. Being an ice class vessel, our ship could easily sail through the pack ice without any trouble. After cruising through the pack ice for a while, perhaps an hour or so, the ship suddenly smashed on a sheet of ice with a jerk and a loud bang and stopped. This sheet of ice, called fast ice (or land fast ice−sea ice that is “fastened” to the coastline, to the sea floor along shoals or to grounded icebergs), is a lot thicker than the pack ice, so that ship couldn’t easily break it to sail through. Unlike pack ice, the fast ice is not a ‘drifting’ sheet of ice; it is stationary, as the sheet is attached to the shore, and could be 2-3 metres in thickness. Fast ice is so thick that there are runways for airplanes and driveways for snow vehicles built over fast ice sheets in Antarctica. One can ride ice scooters –called ‘skidoos’− a joyful mode of transportation quite often used by the members at the station during winters, over it. For short distance transportation of cargoes, sledges are often towed behind the skidoos. Island continent
After the initial bang, the ship would reverse-sail several shiplengths, perhaps 5-6 times the length of the ship, and then, with full throttle, would smack the fast ice sheet once again, breaking the ice for a few more metres. This strenuous process, known as ‘ice breaking’ would be repeated for the next couple of days. If you stand at the bow, the ship’s reverse sail would reveal the last hit it made on fast ice-that would appear as a pointed semi-triangular-shape of ship’s hull, with the shape filled up with broken masses of ice of various shapes. I could see in those broken masses a distinct haziness of extreme chill− as if you are looking at the pellets of dry ice (the solid CO2 ) at a temperature of minus 78°C. I would stand by the ship’s bow looking at these, fancying lifting one of these hazy white blocks, like the hazy blob of Orion nebula you could see through a telescope. These spongy white lumps, a few centimeters across, are called Shuga, as I would learn later. It was at this time that I experienced that feeling of total pin-drop silence so typical of Antarctica. That was the moment I felt for the first time I have arrived in Antarctica− the frozen continent. Island continent
Amongst those Shuga, I spotted yet another mystery, the blue ice! Blue ice has a spellbinding azure hue that you won’t find anywhere on Earth other than polar areas. Blue ice forms when layers of snow, accumulated over the glacier, compresses that squeeze the air out of the ice, to make them very hard and dense. The blue colour is because strained oxygen-hydrogen (OH) bonds of ice molecules absorb the red light, and the blue light gets reflected back; the same reason why a large mass of water− such as the ocean− appears blue. Over the course of my stay in Antarctica, I would see some massive icebergs and glaciers having conspicuous blue ice formations within; it would appear as a shimmering sapphire, or as if the ice is internally illuminated with a potent deep blue light, a very magnificent spectacle indeed. Island continent
When we crossed the Antarctic Circle (66.5°S), another physical spectacle was waiting for me, the polar summer. Antarctica is in the southern hemisphere, and the seasons in the south are diametrically opposite to those we see in the north; winter in the north would be summer in Antarctica. We crossed the Antarctic Circle on 4 January 2017 (Earth’s perihelion, when it is closest to the Sun).It was the middle of winter in India, but in Antarctica, it was the mid-summer. Island continent
The position of the Antarctic Circle, like the Arctic Circle, is not fixed; as of 17 August 2017, it is located 66°33′46.8′north of the Equator. Its latitude depends on the Earth’s axial tilt, which fluctuates within a margin of 2°over a 40,000-year period, due to tidal forces resulting from the orbit of the Moon. Consequently, the Arctic Circle is currently drifting northwards at a speed of about 15 metres per year. Island continent
Owing to the same axial tilt, places within 23.4° of both the poles experience polar summers and winters, two extraordinary phenomena occurring nowhere else in the world. During polar summers, the Sun never sets, so it is full time “day” (midnight Sun) that lasts for many months. During polar winters, the Sun never rises; it is the darkness that prevails for many months. At the South Pole, the Sun rises and sets only once in the whole year, during the equinoxes; in 2017 sunrise will be on the vernal equinox, 23 September, while the subsequent sunset will be on the autumnal equinox, 21 March 2018. September equinox is called autumnal in the northern hemisphere, while it is vernal in the southern hemisphere. March equinox is called vernal in the northern hemisphere, while it is autumnal in the southern hemisphere. In the South Pole, there will be six months of continuous sunlight (summer) between September and March, followed by six months of complete darkness (winter) between March and September.
Antarctica is the most inhospitable continent on Earth; it is the coldest (minimum temperature as low as minus 102°C at Dome-A), driest and windiest. Strong katabatic winds (winds caused by the downward motion of cold air) blow from the interior of the continent towards the Southern Ocean, with speeds up to 327 km/h (technically a “hurricane”). The ice valleys at the interior of the continent are ‘the breeding grounds” of these katabatic winds that often turn into gales. Almost 98% of the continent is covered with permanently frozen kilometresthick (average thickness is 1.9 km) ice sheet that contains 90% of world’s ice. This ice, if you melt, is freshwater (not saltwater); the ice sheets of Antarctica are estimated to contain 70% of our planet’s freshwater Ironically, Antarctica is considered the largest desert in the world, owing to the scanty precipitation that it receives. Some parts of Antarctica had had no rain or snow for the last 2 million years! In recent times, effects of global warming are becoming apparent in Antarctica, with accelerated melting of glaciers, changes in the distribution of plants and breakup of ice sheets. Occurrences of warm winds have intensified in Antarctica, increasingly forming massive sastrugi (parallel wavelike ridges caused by winds on the surface of hard snow, especially in Polar Regions) and melting the glaciers. One such a wind is the “foehn wind”, which is a warm dry wind. Island continent
Antarctica is home to more than 400 subglacial (“below glaciers”) freshwater lakes that are buried deep underneath the ice sheet. Lake Vostok (250km long and 40km wide) is the 7th largest lake in the world), lying 400 metres below Vostok station of Russia (Antarctica’s largest). Many of these lakes are not frozen, thanks to the geothermal effects of the underlying rock bed. Sub glacial lakes are considered to be ‘time capsules’, as they preserved the remnant of habitats when the continent began to freeze. These lakes are interconnected by the sub glacial network of ‘secret rivers’. One such secret river flows through the valleys of Gumburstev Mountains, which lies underneath the ice sheet. The river is so bizarre that the water “flows” uphill, or ‘backwards’, like a capillary action, or like liquid nitrogen flowing against gravity. This is because the kilometers-thick ice sheet pushes the lake like a syringe piston, allowing the water to pump-up through narrow conduits inside the ice against the gravity. Island continent
There are nine glacial meltwater streams (rivers) in Antarctica, with Onyx River (32km long, flowing near McMurdo station) being the largest among them. The lowest accessible point in Antarctica is Deep Lake at Vestfold Hills, which is 50m below sea level. This lake is extreme hypersaline; with salinity almost equal to that of the Dead Sea. This high salinity brings down the freezing point of water; even at minus 20°C Deep Lake is not frozen. Island continent
Scientists have detected life (few species of Haloarchaea, salt-loving archaeobacteria) in this extreme environment of a double whammy: low temperature and hypersalinity. As the conditions at places like these resemble the extremities of young Earth around 3 billion years ago −at the time when life probably originated− these microbes in the deep lake provide clues on the life’s origin and how life could potentially develop on other planets. Alternatively, these life forms might suggest the very last Martians that survived on Mars or the final vestige of life on Earth. At Taylor Glacier in McMurdo dry valley, there is a famous ‘five-storey’ waterfall, known as the Blood Falls, which originates at the centre this glacier and falls into Lake Bonney. The water is from Brine Lake buried deep within the glacier. The red or crimson colour of the water− which is almost three times more saline than seawater− comes from iron and unique iron oxidising microbes. Iron is picked up from the underlying bedrock, and this iron-rich brine oozes through fissures inside the glacier at high pressures and gets oxidised before falling as a ‘blood fall’ to enthral we humans! Island continent
We were based at Bharati Station, Larsemann Hills− India’s newest and most sophisticated Antarctic research station− for the first 45 days of our stay in Antarctica. In the glaciers of Larsemann Hills, I observed various corrugated surface patterns of the ice sheet carved by the wind−most were in the shape of rhombus, several crevasses and melt water patches. I saw sastrugi everywhere. The melting of troughs of waves by the wind action formed these wavelike features, as I would learn later. At Bharati, the first brief night happened by the end of January, and since then nights started increasing quite rapidly. We left Bharati by the end of February, for another long voyage approximately 3,500 kilometres westward of the same continent,towards our second stop, Maitri station−India’s oldest Antarctic station still under operation. Island continent
As the ship approached the Princess Astrid Coast, around 80 km north of Maitri station, I could increasingly spot frazils− slushy icy formations in the supercooled sea surface that flows with water with intact waves (of course, waves cannot form if the sea surface is frozen completely, for example, floe, pack ice or fast ice). Frazil ice is indeed the first stage in the formation of sea ice. I also found thin greasy translucent surface layers of sea that flows with water; as if we were sailing through an electrophoresis gel slab; these are indeed called grease-ice; the second stage of sea ice formation. At several locations I could spot several round formations in the frazil; pancake ice−as these are called. The pancakes indeed resembled the real pancakes, with a diameter around 1 m. And there were Nilas too− similar to pack ice, but very thin (up to 10 cm in thickness) that bends around waves and swells. Island continent
By the time we reached Maitri Station in March 2017, it was already the onset of long Antarctic winter with shrinking day lengths. The March night sky at Maitri was splendid. As Antarctica remains the most unpolluted place on Earth, in both air pollution and light pollution, you can get some of the clearest views of night sky from here. I could see Orion nebula within the Orion constellation towards northeast, as clear as a blob of haziness and our own galaxy the Milky Way extending in North-South direction with clarity unmatched anywhere; no super high-resolution images can measure up the clarity I saw. Right overhead is the Southern Cross (Crux)− a prominent constellation famous for its inclusion in the Australian flag. Island continent
Before the start of the expedition almost everyone had agreed that the southern lights, or Aurora Australis, would be visible only during the mid-winter in Antarctica, which is around July-August, so we will be missing it. While the wintering teams would get ample chance to watch the aurora during the whole of winter, a few of us staying in the summer huts were lucky enough to spot the first aurora at Maitri on the night of 6 March 2017. Watching the live aurora was a breathtaking, unforgettable experience that we had at Maitri. The news of aurora sighting disheartened some of the winterers next morning, who were furious about why we had not informed them over the radio! Virtually every night since then, between 10:30 and 12:30, the spectacular celestial fireworks−sans sound− was clearly discernible towards southeast of the station, for the jubilation of whole station. Perhaps the Antarctic silence would then seem to you deafening, and you would long for a background score at least; perhaps Handel’s ‘music for the royal fireworks’ might sound best. “Now most of the sky was covered with swinging, swaying curtains which met in great whirl overhead: lemon, yellow, green and orange”−exactly the same as in the description by the celebrated British explorer Apsley Cherry-Garrard in his beautiful book The Worst Journey in the World: Antarctic 1910- 1913. On the night of 13 March 2017, the day back home our families and friends celebrated Holi−the festival of colours – we watched the stunning aurora, the variegated Holi colours straight from the heavens. My feeling then has no words in English; perhaps the closest would be ‘wabi-sabi’ in Japanese; appreciation of beauty which is imperfect, impermanent and incomplete. Island continent
Auroras form as charged particles emitted by the Sun during solar flares collide with the particles (gases) of our atmosphere in Earth’s magnetic field. In a common bar magnet that we used in school (and prodigies among us attempted to make perpetual motion machines out of them!), the magnetic force is strongest near poles, and that explains why auroras are seen only near the poles. These atomic collisions excite electrons in atoms of gases in the Earth’s atmosphere. Like us, superexited electrons jump too; they jump from lower energy level to the higher level. After a while, the electrons fall back to the lower energy level (again, like us). Various studies have found excitement from a major lottery win falls back to the earlier state within one year! There is a name for it in cognitive psychology: “Hedonic treadmill”.The difference of energy is emitted as photons (light). The wavelength of these photons (that is, the colour) depends on which atom is excited; collisions with oxygen produce red and green auroras while that with nitrogen produce pink and purple auroras. Intensity of these auroras depends on the strength of Earth’s magnetic field, which changes every single day, as well as that of the solar flares. The solar cycle− increase and decrease in the number of sunspots− that completes once in every 11 years on average is the major factor that influences auroras though; the last peak happened in 2014 and the next peak expected in 2025.After returning from the Maitri, we could still see the aurora from our ship, very clearly indeed. I found yet another peculiarity of aurora; the camera (I was using Canon EOS 60D) captures it far better than our eyes, perhaps owing to the longer exposure time that I had set (around 2 seconds). Island continent
During Antarctic winters when the temperatures slips below minus 40°C, blowing soap bubble would be a fun activity; the bubbles would instantaneously freeze into transparent ice balls, before breaking to three dimensional wafer-thin ice pieces. One can instantaneously generate cloud-like formation in air by sprinkling or splashing the boiling water; the steam sublimates to ice that would appear as cloud. The water droplets in the atmosphere naturally freeze to form ‘diamond dusts’−tiny hexagonal ice crystals that glitter with sunlight (but does not cause fog). These ice crystals refract the sunlight to cause an extraordinary phenomenon called ‘sun dogs’− two more suns appearing on either side of the sun, 22 degrees apart. At times, these ice crystals also create an illusion called ‘22 degrees halo’ with a ring around the sun at 22 degrees from the centre.
Then there is another phenomenon called “green flash”; just before the sunset you could see a green flash emanating from the Sun, sometimes appearing as a ray projecting skyward from the point of sunset. This green flash in fact happens everywhere on Earth, but hardly lasts for a second or two elsewhere, but in Antarctica it lasts for several minutes. This optical illusion is caused by refraction of sunlight, and is enhanced by the mirage. Due to the shorter wavelength, blue colour is expected to refract the most, but it will also be scattered out much faster (therefore sky, ocean, Antarctic blue-ice, etc., appear blue), rendering the green colour to our eyes. Antarctica amazes its visitors with so many optical illusions seen nowhere else on Earth! Island continent
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