Office Hours

1. Office Hours Tue: 12:30 PM to 2:30 PM Wed: 9:00 AM to 10:30 AM & 12:00 PM to 2:00 PM Thr: 9:00 AM to 10:30 AM Course Syllabus can be found at: http://www.wx4sno.com/portfolio/BSU/Fall_2011/ This lecture will be posted AFTER class at: http://www.wx4sno.com/portfolio/BSU/Fall_2011/Lectures/

2. Lesson 17 Weather Maps Hess, McKnight’s Physical Geography, 10 ed. A13 - A18

3. Station Models • In lesson 13 we introduced station models with an emphasis on temperature and air pressure. • We will now cover station models in-depth and discuss the symbology associated with different weather conditions

4. Station Models, cont. • Temperature • Located in the upper-left corner • Given in degrees Fahrenheit • For example, 64°F in the example above

5. Station Models, cont. • Dew Point Temperature • Located in the lower-left corner • Given in degrees Fahrenheit • For example, 58°F in this example

6. Station Models, cont. • Wind Direction • Indicated by a shaft or “wind barb” protruding from the station model • Can be positioned anywhere around the station • The direction it points toward is the direction from which the wind originates • In this example, the wind is coming from the southeast (SE)

7. Station Models, cont. • Wind Speed • Wind speed is provided along the wind barb • To determine wind speed, simply add the barbs • No barb = calm winds • ½ barb = 5 knots • 1 barb = 10 knots • 1 pennant = 50 knots • Recall: 1 knot = 1.15 MPH 1 knot = 1.9 KM/HR

8. Station Models, cont. • Wind Speed, cont. • For example, what would be the wind speed from our example? • Answer: 15 knots

9. Station Models, cont. • Sea Level Pressure • Located in the top-right corner • As we’ve already covered, this number is the last three digits of the observed pressure reading in millibars (mb) • In this example, the pressure is 1002.7 mb

10. Station Models, cont. • Sea Level Pressure Change • Located directly below the pressure reading • Given in tenths of a millibar • Simply add a decimal point between the two numbers • “+” means the pressure has increased x-amount over the past 3 hours • “-” means the pressure has decreased over the past 3 hours • In this example, the pressure change is an increase of 2.8 mb

11. Station Models, cont. • Weather Conditions • Current weather conditions are listed between the air temperature and the dew point temperature • For our example, fog was reported at this weather station

12. Station Models, cont. • Weather Conditions, cont. • There are various symbols for different types of weather phenomenon • You are not expected to know these…a few are given here for general reference:

13. Weather Maps from the NWS • http://www.hpc.ncep.noaa.gov/dailywxmap/index.html • These maps provide both surface conditions, upper-air conditions, precipitation, and high & low temperatures • Let’s discuss each of the maps given…

14. Surface Weather Map • Surface maps provide a weather “snapshot” taken at 7:00 AM EST • Locations of high and low pressure systems • Locations of frontal systems, as well as precipitation (green) • Isobars show surface pressure (mb) • Dashed isotherms are plotted for 32°F and 0°F

15. Surface Weather Map

16. Some General Rules • Generally, weather systems move from west to east with time • As a frontal system or low pressure system approaches an area, air pressure decreases and clouds/precip increase • As a frontal system or low pressure system moves away from an area, air pressure begins to increase which results in clear skies and no precipitation • Remember, high pressure near an area results in fair/clear skies and low pressure near an area results in clouds and precipitation

17. Surface Temperatures • High and low surface temperatures for the previous 24 hours are given • Precipitation over the past 24 hours is also plotted

18. 500 mb Height Contours • The last map provided illustrates the conditions of the upper atmosphere at 500 millibars • The 500 mb height (or elevation) above sea level is plotted across the U.S. • Given in dekameters (1 dkm = 10 meters) • Height values change with fluctuations in pressure • High 500 mb elevations indicate high pressure below that region • Low 500 mb elevations indicate low pressure below that region • For reference, the 500 mb average elevation is 5600 meters.

19. Lesson 20 Faulting Hess, McKnight’s Physical Geography, 10 ed. pp. 405 - 408

20. Types of Faults • Faulting occurs when stresses forcibly break apart and displace rock structure • This displacement can be horizontal, vertical, or a combination of the two • Several different kinds of faults, but generally can be separated into four categories

21. Types of Faults, cont.

22. Normal Faults • Movement is primarily vertical • Normal faulting is the result of extensional (tensional) stress • This stress pulls apart the landscape (shown with arrows) creating a steep fault plane

23. Reverse Faults • Movement is primarily vertical • Reverse faulting is the result of compressional stress • This stress pushes the landscape together (shown with arrows), eventually creating a steep fault plane

24. Thrust/Overthrust Faults • Movement is also primarily vertical • Thrust faults are also caused by compression, but the overthrust block overrides the downthrust block at a low angle

25. Strike-slip Faults • Movement is primarily horizontal • Strike-slip faults are produced by sheering stresses • Think of the stress exerted when you press your hands together and try to move them parallel to one another

26. Landscapes from Faulting • Different landscapes are created from different types of faulting • Normal faulting results in such areas as the Basin and Range region of the western U.S.

27. Landscapes from Faulting, cont. • Thrust faulting uplifted sedimentary rocks millions of years ago creating the Appalachian Mountains • Erosion has resulted in the mountains being warn-down

28. Landscapes from Faulting, cont. • The San Andreas region of California is characterized by strike-slip faults • The sudden movement of these faults result in the earthquakes common to Southern California

29. Landscapes from Faulting, cont. • The Sierra Madre Mountains of Mexico were created by reverse faulting • Compressional stress forces the landscape to rise, creating mountains or a mountain range