Definition:
* Foehn (pronounced "fuhn") is a meteorological term for a warm, dry wind that develops when moist air is forced to rise over a mountain range.
* As the air rises, it cools and releases its moisture as precipitation on the windward (upwind) side of the mountain.
* The now dry air descends on the leeward side, warming adiabatically (due to compression). This creates a warm, dry wind called a foehn.
Key Characteristics:
* Warm and dry: Foehn winds are significantly warmer and drier than the air on the windward side of the mountains.
* Strong and gusty: Foehn winds can be strong and gusty, sometimes reaching speeds of over 100 km/h (62 mph).
* Rapid temperature changes: Foehns can cause rapid and dramatic temperature increases, sometimes by as much as 20°C (36°F) in a short period of time.
Examples:
* Chinook wind: This is a foehn wind that occurs on the eastern slopes of the Rocky Mountains in North America.
* Santa Ana wind: This is a foehn wind that blows into Southern California from the desert.
* Zonda wind: This is a foehn wind that occurs in the Andes Mountains of South America.
Effects:
* Wildfires: Foehn winds can dry out vegetation, making it more susceptible to fire.
* Snowmelt: Foehn winds can accelerate snowmelt, which can lead to flooding.
* Weather hazards: Strong foehn winds can cause damage to property and infrastructure.
In summary:
"Foehn" is a specific type of wind that is warm, dry, and strong, and occurs on the leeward side of mountains. It is caused by the adiabatic warming of air that has been forced to rise over a mountain range and release its moisture on the windward side.