Every schoolchild knows about Rudolph the Reindeer and his magic red nose. However, not many people know that Rudolph’s real-life counterparts really do have a magic nose. The colder it is, the better a reindeer’s nose is in keeping the animals warm and hydrated.
Reindeer live in harsh conditions during the winter. On the fells and mountains of mainland Norway, temperatures sometimes drop to 30-40 degrees Celsius below zero. Little food is to be found when snow covers the landscape, and reindeer have to chew cold snow to get water. So how do reindeer survive when it is so very cold?
Their thick fur is a good insulator, but that is not the whole explanation. Reindeer also survive by releasing as little heat as possible to the environment through their nose – and by conserving as much water vapour as possible.
What is so special about Rudolph’s nose?
Does Rudolph’s nasal structure explain why reindeer do so well in cold climates? This hypothesis interested PhD student Elisa Magnanelli and her supervisors at the Norwegian University of Science and Technology (NTNU), Signe Kjelstrup and Øivind Wilhelmsen, who decided to carry out a study, which has been published in the Journal of Non-Equilibrium Thermodynamics, to understand this wonder of nature.
Reindeer on treadmills
Magnanelli and her supervisors work closely with scientists at UiT—The Arctic University of Norway in Tromsø, who brought real reindeer into a climate chamber and had them walk on a treadmill to study their respiration. Results showed that reindeer have a fantastic ability to change the temperature of the air they inhale before it reaches the lungs, and vice versa.
On exhaling, the reindeer cools its warm breath instantly, in order to conserve as much body heat as possible. In addition, the reindeer breathes out minimal moisture when it exhales – which is especially important when the access to water is only icy snow.
Huge inner nose surface
The powerful reindeer snout is made up of cartilage and bone, fleshy structure, mucous membranes and lots of blood vessels. The researchers carried out CT scans of reindeer nose slices in able to acquire cross-sectional images of the reindeer’s breathing organ in its entire length. The pictures showed that the nose interior has an unusual and strange structure that resembles a seashell.
The scientists also measured the inner surface area, which turned out to be enormous. The expansive inner surface provides plenty of space for exchanging heat and water vapour between the air and the nasal wall.
What is nature’s recipe?
Rudolf’s incredible ability to convert the cold air in his nose to warm air in record time is another one of Mother Nature’s secret recipes. How is it possible? The NTNU researchers decided to find out.
Mathematical reindeer nose
By creating a mathematical model of a reindeer’s nose by obtaining vital measurements, such as the amount of air a reindeer inhales when it breathes, the researchers were able to use the data to develop and assess the accuracy of a computer program specially designed to simulate a reindeer’s nose. In addition to the data-simulated reindeer nose, the scientists also created a computer program of a simplified cylinder-like data nose that served as a reference case. The scientists conducted repeated experiments in both data noses, with surprising results.
An ingenious design
Magnanelli’s simulation experiments, carried out over 1600 kilometres and 15 degrees of latitude from the reindeer’s northernmost stomping grounds, shows that their nose mostly works according to the principle of minimum energy loss. This energy dissipation in the form of friction is what scientists call entropy production. The brilliant reindeer nose ensures that entropy production is nearly always uniform. This means that the animal as a whole loses the least possible amount of energy into the environment when it breathes.
The colder the weather, the more effective the nose
The study showed that the colder the air, the more energy efficient a reindeer’s nose is compared to a nose without the seashell shape. At 30 degrees C below zero, the reindeer’s seashell-shaped nose works even better than it does at 10 degrees below zero.
The researchers found that the cold air is drawn in through the nostrils, passing over the large inner surface area, which consists of nasal mucus, located outside the nose structure and with many small blood vessels. The warm blood instantly and continuously heats up the mucus, which in turn heats the air being inhaled.
There are many reasons why scientists and engineers are eager to understand how the reindeer’s nose works. Reindeer noses serve as excellent heat and vapour exchangers because of their complicated seashell-like shape.
In fact, it is entirely possible that this newly acquired knowledge may one day come in handy when industrial designers need to create balanced ventilation systems for homes and cottages in extremely cold climates. It may also provide an important contribution in building net-zero homes in the Arctic when the time is right.
In fact, it would probably be a perfect project for Santa’s workshop at the North Pole.
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