Mar 1, 2017

Highest Recorded Temperatures In Antarctica Announced And They May Surprise You

by
Marshall Shepherd
,
Forbes

...

An intriguing aspect of the Antarctic records is that they were likely associated with "Foehn-type winds" often referred to as "Chinook winds" here in the Rocky Mountain region of the United States. The American Meteorological Society glossary defines Foehn winds as,

A warm, dry, downslope wind descending the lee side of the Alps as a result of synoptic-scale, cross-barrier flow over the mountain range.

The specific reference to the Alps provides clues about the origin of the word, but the winds exist in Antarctica as well. Though not as well-studied, a 2010 research paper published in the Journal of Climate concluded that Foehn winds resulting from modified air flow in the lee of mountain barriers in the Mcmurdo Dry Valleys are fairly frequent. Why are these types of winds so warm? It has to do with something called adiabatic compression. Adiabatic means no heat is exchanged between a thermodynamic system and the surrounding environment. On the lee side of mountains, air descends and is compressed (think about your hand pressing down on a sponge). Such compression also leads to "adiabatic warming" of the air.