1. Weather and Climate Always changing but always the same PowerPoint 97 To download: Shift LeftClick Please respect copyright on this material

2. Key Points u Why the winds blow u Viewing the clouds from satellites u Prediction of weather and climate

3. warm cold Incoming radiation vs latitude

4. highlow TropicsPoles temperaturepressure high warmcold Warm air rises u Transfer of heat pole wards –Warm air polewards –Cold air equatorwards

5. Coriolis Force u Due to rotation of Earth about its axis once/day u Only important for large scale winds, ocean currents u In the Northern hemisphere, moving things are deflected to the right –Clockwise flow round high pressure – Anti-clockwise flow around low pressure u Opposite in Southern hemisphere.

6. Large Scale Winds Northern Hemisphere u Coriolis & pressure forces balance u Clockwise around high pressure u Anti-clockwise around low pressure High Pressure Low Pressure Air Motion Coriolis force pressure gradient HL

7. Why the Winds Blow u Variation of solar radiation with latitude forces variation of temperature u Warm air rises with associated differences in pressure u Pole ward heat flux tends to equalize temperature u Coriolis force deflects moving air to the right in the Northern hemisphere, to the left in the Southern hemisphere

8. Clouds & Wind Movies u Rotating Globe Rotating Globe u Global Clouds (Molleweide) Global Clouds These are Mpeg (.mpg or.mpeg) format. You will need a VMPEG or equivalent viewer

9. Key Points u Why the winds blow u Viewing the clouds from satellites u Prediction of weather and climate

10. Opacity of Atmosphere & principal satellite channels u Fraction of radiation absorbed by cloud-free atmosphere u Approximate range of instrument sensitivity From Sun From Earth 0 % 50 % 100 % 20151050.70.50.30.10.07 Wavelength (micrometers) VisIRWV

11. Images from Satellites u Visible (intensity) Midday, reflected solar u IR (intensity) Usually IR images are black and white reversed from this

12. Infrared and Water Vapor Conventional view White & dark reversed for both images u IR Window u Water Vapor

13. Clouds from Satellites u Visible u Infrared window Conventional (reversed) image An evening view

14. Hurricane George 9/23/98 u Visible u IR (reversed)

15. Key Points u Why the winds blow u Viewing the clouds from satellites u Prediction of weather and climate

16. Prediction of Weather and Climate u Modeling u Prediction of chaos u Averages and variability

17. Forces on an Air Parcel Temperature Moisture Velocity etc. up down North - South East - West gravity pressure gradient coriolis buoyancy friction acceleration

18. A Grid for Numerical Weather Prediction

19. Dependence of Forecast on Input Data 10 km 1 km 100 m surface -100 m Latitude Equator 45 90 45 90 12 - 36 h 1 - 2 d 1.5 - 4 d 3 - 5 d 4 - 10 d 1 week - 2 months Height

20. Outcomes and probability Temperature o F A climatological prediction Average

21. Sources of Information u Horel & Geisler Chapter 3 u http://www.ssec.wisc.edu