Mountain Meteorology Meteorology INSCC TH 10:45 – 12:05 John Horel Jim Steenburgh Photo: J. Horel Mountains complement desert as desert complements city, as wilderness complements and completes civilization. Edward Abbey

Course Objectives and Content  Understand the influence of the earth’s orography upon weather and climate  First Half- John Horel  Geographical controls of mountain weather and climate  Terrain-forced flows  Flow interaction with complex terrain Photo: J. Horel

Course Content (cont.)  Second half- Jim Steenburgh  Orographically modified cyclones  Orographically trapped disturbances  Orographic precipitation  Invited presentations  Fire weather  Air quality  Avalanches  Surface transportation Houze 1993

Grading  40%: Homework, class participation, literature reviews  20%: Participation and writeup of results from field experiment  20%: 1 st half quiz  20% 2 nd half quiz

Source Material  Mountain Meteorology. D. Whiteman  Mountain Weather and Climate. R Barry  Atmospheric Processes over Complex Terrain. W. Blumen  Influence of Mountains on the Atmosphere. R. Smith Advances in Geophysics. 21.  Additional Reading

Reading Assignments  Many available on-line. To save trees, you are to access them on-line from campus and print them as needed  x-html x-html

First Reading Assignment  First reading assignment: Barry, R. G. (1978): H. B. de Saussure: the first mountain meteorologist. Bull. Amer. Meteor. Soc., 59,  Summarize in a few paragraphs: (1) who Saussure was; (2) how did he make the measurements and what were his results regarding the decrease of temperature with height; (3) what other contributions to mountain meteorology did he make?  Due: via at beginning of class on Aug. 30. Send to Be prepared to discuss the reading during that class.

Field Project  Analysis of wind circulations on ski- jump slope  Weather permitting  Set up on Friday September 28  Observations Saturday morning September 29  Takedown in afternoon  Requires planning in advance by class to design useful field project  Requires analysis of data after data collection completed Photo: J. Horel

VTMX Workshop  September  Useful presentations on local wind circulations in Salt Lake Valley  Plan on attending a few hours at some point instead of class on the 11 th (and 13 th ?)

What is a mountain?  Common usage:  600 m or more of local relief defines a mountain  Less than 600m is a hill  High mountain/alpine areas (Troll 1973; Arct. Alp. Res., 5, 19-27):  Relative to terrain features  Upper timberline  Snow line Himalayas: Photo credit: NASA/Science Photo Library

What are the effects of mountains?  Substantial modification of synoptic or meso scale weather systems by dynamical and thermodynamical processes through a considerable depth of the atmosphere  Recurrent generation of distinctive wx conditions, involving dynamically and thermally induced wind systems, cloudiness, and precipitation regimes  Slope and aspect variations on scales of m form mosaic of local climates (Barry 1992)

Effects of Mountains Carruthers and Hunt 1990

Whiteman (2000) m/ipa/A html

Precipitation

Barry 1992

Barry (1992)

Mountains  % mountains as fraction of total land surface (land 30%)  m 10%  m 3%  m 3%  > 3000 m 4%  Total 20% Barry 1992  %mountain as fraction of earth 6%

Mt. Everest     Pix.html Pix.html  Height of Mt. Everest: 8848m (

High Elevation Observatories  Mt Washington   Storm Peak Laboratory 

Geographical controls of mountain climate (Barry 1992)  Latitude  Continentality  Altitude  Topography Jeff Klein. SLC BLM)

Thermally forced terrain circulations  Mountain-valley winds  Slope flows  Peter Sinks Experiment  VTMX  lake breeze

Flow Interaction With Complex Terrain Photo: J. Horel  Buoyancy oscillations  Flow over vs. around obstacles  Kinetic and potential energy of flows  Mountain waves  Gravity wave drag  Trapped lee waves

Downslope Windstorms  Conceptual models  Observations  Numerical studies  Gap winds L. Darby & R. Banta, ATDD/ETL

Other subjects  Orography and the General Circulation  Mountain torque  Physiology of high altitude  Climate change at high altitude

1 st Homework Assignment  Bring in a couple (to as many as you want) of mountain and mountain weather related photos  Be prepared to say a few words about 1-2 photos  If you’re willing to allow use of the photos for this class and future classes, scan the images on the PC in Rm 480 (details to be provided, but don’t leave them with me)  Due: whenever

Homework Assignment #2  (1) Find 5 interesting and useful internet web pages related to mountain weather, mountain climates, or alpine environments  (2) Send me in 1 the web addresses with a 1-2 sentence description of the content of each page  (3) Provide at least 2 scientific, literary, or artistic (music/art) definitions or descriptions of mountains. Not from dictionaries  (4) Provide a reference/source for that definition and send it in the same as that used above  Due August 30

Parameters used to define flow (Smith 1979) ParameterSymbolUnitsTypical Value Mountain heighthkm1 Width downstreamLxLx km10 Width crossstreamLyLy km100 Flow layer depthHkm1 PBL; 10 troposphere Incoming windspeedum/s10 Incoming wind shearuzuz s Stability frequencyNs Coriolis parameterfs Buoyancy/reduced gravity b =  g  m/s