It’s 21 June, it’s Winter Solstice here in the Southern Hemisphere, and at just after 5pm in the afternoon in New Zealand, the shortest day of the year is already dwindling fast.
And what a winter solstice it has been for the country – some of the worst snow storms in recorded history covering much of the South Island in a thick white blanket, while other areas are bludgeoned by extreme tropical storms. Over the last two days, the capital Wellington has been one of the worst hit areas, with flooding and winds of up to 200km/h.
Scary stuff, but then again, winter solstice does kind of give one that feeling that from here it can only get better – longer days, increasing temperatures, new growth, new life…
And if nothing else, crisp winter mornings are just the greatest for some amazing frosty photo opportunities all around us. That’s the joy of photography – no matter how cold, or how extreme the conditions, there’s always something amazing to photograph (often the more extreme, the better, in fact!).
To everyone in the southern hemisphere, enjoy the opportunities the cold bring. And for my northern friends, have a great summers day (hard to imagine down here, I have to admit)!
Today we celebrate an event that may be somewhat unthinkable on this day to our Northern Hemisphere friends, especially everyone suffering in the US heat. On this day, back in 1983, the coldest ever temperature on earth was recorded at Vostok Station, Antarctica.
So how cold was it? Well, believe it or not, but exactly 19 years ago, the poor folk at Vostok Station recorded an icy -89.2°C (-128.6°F).
That’s pretty darn chilly… Certainly not a temperature you want to be exposed to for any length of time. Prolonged exposure to very cold temperatures has some interesting effects on the body.
Goose pimples and shivers
When the temperature falls below 8°C, touch sensitivity starts being compromised. Goose pimples appear, lifting hair follicles as the body tries to protect itself from the cold. Unfortunately this does not help us humans much, because we don’t have enough body hair to have a significant effect, but you can imagine how this can be very useful to an animal with a dense fur coat.
The next step is shivering, as the body starts to increase its heat production by working the muscles – shivering is said to increase the body’s heat production five-fold.
Your skin also starts doing strange things. From below 10°C, the surface blood vessels start to dilate (your skin becomes red). As it gets colder, the blood vessels start constricting again, to avoid heat loss through your extremities. This is followed by alternating periods of dilation and constriction, as the body tries to balance the supply of oxygen and nutrients to the skin, with protection from heat loss. So you may start sporting an interesting blend of red and white skin tones.
During extended exposure to cold, the body has to start making decisions on how its available heat should be best applied. In order to keep vital organs warm and avoid hypothermia, our extremities – fingers, feet, ears, nose – will be allowed to cool down, and blood flow to the extremities will also be reduced (to avoid blood cooling down as it circulates to the extremities). If this situation persists, it can lead to frost-bite, where the cells close to the skin surface start freezing and die. When heat returns to these cells, it results in swelling and blisters, forming a hardened black layer.
In extreme conditions, the frostbite can reach deeper layers of muscle and bone, resulting in permanent tissue damage, and ultimately amputation of body parts – a fate that has befallen many polar explorers and extreme mountaineers.
Even though the body will do its best to maintain its core temperature, even sacrificing body parts in the process, it cannot keep up the heat if exposure to extreme cold continues. Next the body will slow its metabolism to minimize blood flow and limit energy loss. At some point, however, the body core starts to cool, and hypothermia sets in. Not much of a core drop is needed for this – clinically, hypothermia sets in when the core temperature drops below 35°C.
First symptoms of hypothermia include reduced motor skills and slowed reaction times. Judgment also becomes impaired, with the dangerous result that the hypothermia sufferer may lose the ability to recognize the condition.
As the core temperature drops below 35°C, the body starts shivering more violently in an attempt to reverse the situation. You get more sluggish and tired, with a strong need to give up and go to sleep. Below 32°C the shivering stops, as there is no energy to keep it going, resulting in even quicker heat loss.
Unconsciousness sets in when the body core drops below 30°C. In a final primal attempt to avoid death, the heart rate and breathing slows down severely, to the point where the metabolism is so slow that the sufferer basically appears to be dead.
Below 28°C cardiac arrhythmias become more common. If the sufferer has not yet died, the heart finally stops beating at a core temperature of about 20°C.
Gender and age matters
Interestingly, women can survive extreme cold better than men. The temperature gradient from skin to body core is greater in women – women’s bodies will more readily allow the skin surface and extremities to cool down, while better protecting core temperature. So while a woman may sooner suffer frostbite, her warm core is likely to keep her alive longer. Women also tent to have a higher subcutaneous fat percentage, further helping to protect core temperature.
Age also plays a role, with people losing their ability to handle extreme cold as they age. Children are more likely to recover from the effects of extreme hypothermia – their organs appear less likely to be affected by physical stresses that may be fatal to older organs.
Brrrrrr! Chilling stuff! Suddenly the chilly New Zealand mornings seem decidedy mild. Enjoy the weather – whether you’re basking in the northern summer heat or shivering in the southern winter cold. It could have been worse!