Intro to Mountain MeteorologyCourse OutlineSlide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Hw #1: Complex Terrain Essay 1: Define ‘Complex Terrain’ 2 pages, Use 3 references Read: Meybeck et al. 2001 (MRD)Intro to Mountain MeteorologyDr. Craig ClementsSan José State UniversitySpring 2010Course Outline•Mountain Climates- energy balance in mountainous areas- large-scale effects of mountains on flow- mountain torques- climatology of major mountain ranges•Mountain WindsTerrain forced flowsa. Flow over mountainsb. Mountain wavesc. Flow around mountainsd. Gap flows•Thermally-driven mountain windsa. Slope flowsb. Mountain valley winds-topographic amplification factor-cold air poolsc. Mountain-plain winds•Special TopicsAir pollution and dispersion in mountainous terrainFire weather and Smoke ManagementConvection in mountainsPrecipitation processes over mountainsAvalanche mechanics and snow dynamicsSnowpack and glacier runoff related to mountain energy balanceRoderick Peattie in Mountain Geography (1936) suggests:Mountains are: (1) impressive, (2) enter into the imagination of people living in their shadow, and (3) have individuality.Elevation > 300 m MSLElevated and dissected landscapeObjective definition should include:Elevation (insufficient criterion, e.g., Great Plains)Local relief (Grand Canyon?, incised into plateau)Steepness of slopeThe amount of land in slopesTroll (1973) High mountain areas:Upper timberlineSnow line during Pleistocene (produced distinctive features)Lower limit of periglacial processes (solifluction, etc.)Common usage in North America>600 m of local relief - mountain<600 m of local relief - hillWhat is a mountain?Why Mountains affect our Weather?If the earth were greatly reduced in size while maintaining its shape, it would be smoother than a billiard ball. (Earth radius = 6371 km; Everest = 8.850 km)Nonetheless, mountains have a large effect on weather. Why is this, if they are so insignificant in size?Answer: the atmosphere, like the mountains, is also shallow (scale height 8.5 km), so mountains are a significant fraction of the depth of the atmosphere.But, this answer underestimates mountain effect for two reasons:• Stability gives the atmosphere a resistance to vertical displacements• The lower atmosphere is rich in water vapor so that slight adiabatic ascent brings the air to saturation.• Example: flow around a 500-m mountain (<< 8.5 km) could include 1) broad horizontal excursions, 2) downslope windstorm on lee side, and 3) torrential orographic rain on windward side. Smith (1979)Distribution of mountains on the globeBarry (1992)Everest Nepal 29,035/8850Aconcagua Argentina 22,841/6962McKinley Alaska 20,320/6194Kilimanjaro Tanzania 19,340/5895Elbrus Georgia 18,481/5633Puncak Jaya Indonesia 16,502/5030Vinson Massif Antarctica 16,066/4897Highest Peaks By ContinentMountains of North AmericaWhiteman (2000)Highest point?Denali (Mt. McKinley), Alaska20,320 ft. (6194 m)Lower 48 States?Mt. Whitney, CA 14,496 ft. (4,418 m)Lowest?Iron Mountain, Florida 330 ft. (100 m)Mountains of West USWhiteman (2000)Value4000 00 m0 m4000 m4000 mElevationElevationWhat about California?Highest point in the Contiguous US is Mt. Whitney (14,496 ft)Has many mountain ranges:Coast MountainsSierra NevadaCascade MountainsMountains of Eastern USWhiteman (2000)Thermally-Driven Circulations in Mountain TerrainValley GeometryWhiteman(2000)Yosemite Valley, Yosemite National ParkCampfire smoke plume-Shallow inversion LayerDownslope flows (drainage flows)Meteor Crater 2006Up-Valley and Down-Valley Surface Winds(Measured in Yosemite National Park)Date and TimeA SODAR (sound-detection-ranging) is similar to RADARYosemite National Park, 12 Aug. 2003Vertical Structure of Down-Valley Winds‘Nose’ of Down-valley windNose is location of Wind speed maximumCold Air PoolCold Air Pool(Ekhart 1948)Defining the mountain atmosphere(Barry 1992)Defining the mountain atmosphere(Barry 1992)Defining the mountain climate: Snow line Timber lineGeographical Controls of Mountain Meteorological ElementsLatitudeContinentality AltitudeTopographyHw #1: Complex TerrainEssay 1: Define ‘Complex Terrain’ 2 pages, Use 3 referencesRead: Meybeck et al. 2001