FAA Flight Instructor Airplane (FIA)Weather and Weather ServicesMedium
A pilot departing Denver notices a rapid rise in temperature and a marked drop in humidity as a strong westerly wind descends from the Rocky Mountains, causing dry, gusty conditions at the surface. What is this phenomenon called?
- ASea breeze front
- BLand breeze
- CChinook (foehn) wind
- DKatabatic drainage wind
Show answer & explanationAnswer & explanation
Correct answer: C. Chinook (foehn) wind
A Chinook or foehn wind occurs when air descends the leeward side of a mountain range, warming adiabatically and drying out, producing rapid temperature rises and low relative humidity, often with strong gusty winds—characteristic of conditions on the eastern side of the Rockies.
Why the other options are wrong
- A. Sea breezes are coastal, thermally driven local winds unrelated to mountain descent.
- B. Land breezes are nighttime coastal winds blowing from land to sea, unrelated to mountains.
- D. Katabatic winds are typically cold drainage winds flowing downhill at night, not warm and drying.
Chinook (Foehn) Wind
A warm, dry, often gusty wind that descends the leeward slopes of a mountain range, caused by adiabatic compression as air sinks and warms, common on the eastern slopes of the Rockies.
- Warms and dries adiabatically as it descends
- Can cause rapid, significant temperature rises
- Known as foehn in Europe, chinook in North America
Memory trick: Chinook chews snow away with warm dry breath