In Greenland , in recent days temperatures of 20 or 30 degrees above the average have been registered, even reaching positive temperatures in many parts of the great Arctic territory, as warned by the Danish Meteorological Institute on December 22.
In the capital, Nuuk , on December 20 the temperature was 13 ºC, when the average temperature at this time of year is usually -5.3 ºC , while, in the north, in Qaanaaq, the mercury reached 8.3 ºC, when the usual temperature tends to be originally -20.1 ºC.
According to experts, ” one of the reasons why we see high temperatures is the foehn meteorological phenomenon” , consisting of a fairly common hot wind on the largest island in the world.
Although it would be a phenomenon already observed, experts have been alarmed, given that “it is a bit unusual for it to occur in such a large area” and, above all, “simultaneously over a long period of time”, given that the phenomenon it spans most of the west coast and part of the east coast .
However, these temperatures are not without precedent: neither absolute records nor the records of the last thirty years have been broken for a month of December. And experts point out that, in the Arctic, warming is being three times faster than in other areas .
As they mentioned, “global warming underlies the high temperatures we see in Greenland today, and makes them generally higher than in the past.”
During the summer months, a heat wave , with temperatures more than 10ºC above the average for that time of year, caused an episode of “massive” melting of the Greenland ice sheet .
At that time, 8 billion tons of ice per day had already been lost, twice the average rate during the summer period. In addition, on August 14, 2021, another alarming sign was recorded: it rained on top of Greenland’s highest point (3,216 meters), something that had not happened until that moment.
When a current of air coming from the South meets a big enough obstacle, and cannot get around it, the air experiences an orographic elevation. When the wind gains altitude, the atmospheric pressure drops and is reduced, cooling between 0.5 ºC and 0.65 ºC, approximately, every 100 meters.
The air then undergoes an adiabatic expansion, cooling down to a condensation point, which results in precipitation in the form of rain (or, more often, in the form of snow).
When the air has passed over the top, blocked by stable air, it tends to descend and, on this occasion, undergoes adiabatic compression that causes an increase in air temperature, heating it. What’s more, the more we descend in altitude, the greater the pressure, so that the air ends up heating up.
It is this difference that is observed in the air between the period in which it rises, where the humidity is higher, and it is much colder (generating precipitation), and the period in which it descends, just at the time it develops. the particularly dry and hot wind. It is the phenomenon of foehn .
Hence, it is essential that the wind has to run into a mountain in a perpendicular way, being forced to climb, and that the air is stable above the top, so that the wind descends through the other, forming the dry wind and hot.
