Flashcards in Chapter 17 (PPT) Deck (36):
Where do 'Foehn' Downslope Winds occur?
What is the temperature of 'Foehn' Winds?
Where do 'Bora' Downslope Winds Occur?
What is the temperature of 'Bora' Winds?
Where do 'Chinook' Downslope Winds Occur?
What is the temperature of chinook winds?
Where do 'Santa Ana' Downslope Winds occur?
What is the temperature of 'Santa Ana' winds?
Where do 'Katabatic' Downslope winds occur?
Antarctica and Greenland
What is the temperature of 'Katabatic' winds?
what are the 5 Downslope winds?
For foehn downslope winds, would the new airmass be colder or warmer than the one it replaced?
Will be warmer than the airmass replaced
For Bora downslope winds, would the new airmass be cooler, or warmer?
Will be cooler that the airmass replaced
What are Mountain Waves?
When a large scale weather patterns produce a strong, deep flow of air across the Rockies, The peaks act like Rocks in a stream bed.
Upwind side of mountain range
Downwind side of a mountain range.
A series of waves in the flow downstream from a mountain
Are Lee waves visible?
No, they are invisible
What types of clouds form in Lee Waves?
Lenticular Clouds. (Visible)
The Hydraulic Jump?
Marks the transition from strong winds upstream of the jump to weaker surface winds downstream of the jump.
What 3 factors determine the temperature of air in downslope windstorms?
-Latent Heat corresponding to amount of precipitation falling out of chinook cloud wall
-Adiabatic Warming During Descent
What 3 weather features are required for a chinook to form?
-A stable layer (inversion) about 1-2 km above mountaintop
-Strong Surface pressure gradient across mountains (From east to West)
-Strong, Westerly winds at ~700mb (about mtn top)
An area of low pressure on the lee side of the mountains
How does the sea level pressure change from west to east across colorado?
It decreases quite a bit
How do the temperatures along the colorado front range compare to the temperatures further east?
Santa Ana Winds?
The name given to downslope windstorms in Southern California
What weather conditions are required for Santa Ana winds to form?
-Strong high pressure over great basin
-Strong North-South pressure gradient over southern California
-An inversion layer above mountaintop level may also be needed
How do Santa Ana winds compare to chinook winds in colorado?
Winds are easterly, and also less extreme than chinook winds
When do the strongest Santa Ana winds typically occur?
Late fall and winter (When grass/brush is quite dry)
What hazards are associated with Santa Ana Winds?
Fires, and resultant smoke/pollution
How often do Santa Ana winds occur?
!20 times per year, lasting 36 hrs on average.
A cold, downslope wind that is the result of cold air flowing downslope under the force of gravity.
How do Katabatic Winds Form?
Simply from having a dense pocket of cold air dorm ar high elevations, which spills over the edge and rushes towards the surface.
How do Katabatic Winds Differ from the downslope windstorms discussed above?
There are largely a density effect, where as chinooks etc. are a dynamic, mountain wave effect.
Where are katabatic winds most likely to occur?
Antarctica, Greenland and Patagonia