Chapter 9 Wind: Small Scale and Local Systems Flashcards
what is the microscale?
diameter: < few meters
lasts: seconds-few minutes
-gusts, eddies (tiny whirls of air)
what is the mesoscale?
diameter: few meters-100km
lasts: few minutes-day
-thunderstorm/shower
-fog
-local winds
what is the synoptic scale?
diameter: 100km-2000km
lasts: days-2 weeks
-hurricane/tropical cyclones
-fronts
-high and low pressure system
what is the planetary scale?
diameter: 2000km+
lasts: permanent feature
-climate
what is a boundary layer?
lowest ~1km above Earth’s surface, where friction causes small wind patterns
what is a wind shear?
wind that changes speed and/or direction with height
creates Eddies
on the microscale winds influence: soil, snow, vegetation, and water
what is thermally driven circulation?
pressure difference aloft that creates winds at surface
-PGF causes winds to travel from high to low
what is a sea breeze?
breeze at surface from sea to land. caused from high (land) to low (sea) pressure aloft
what is a land breeze?
breeze at surface from land to sea. caused from high (sea) to low (land) pressure aloft
what is a valley breeze?
warm air rises on mountain slopes during the day
what is a mountain breeze?
cold, dense air sinks at night around mountain
what are mountain winds?
local but not due to heating difference
what are katabatic winds?
cold wind ruses down elevated slopes, mainly in antartica
what are chinook winds?
warm downslope winds on the leeward side “snow eaters”
what are the santa anna winds?
warm dry air that blows from east to northeast down canyons into southern California
dries out vegetation
