Weather Systems & Cloud Types

1. Weather Systems &Cloud Types

2. Air Masses • Bodies of air that bring distinctive weather features to the country. • A mass of air in air that is very uniform in temperature, pressure, and humidity. • Polar = cold • Tropical = warm • Maritime = moistContinental = dry

3. Air Masses • May cover several millions of square kilometers and extend vertically throughout the troposphere

4. Pressure of Air Masses • Air Pressure = weight of air acting on an area • Warm Air has more KE and spreads out more. • Therefore, it’s less dense and has less weight . • This means less pressure. Warm Air Masses are less dense and have Lower Pressure

5. Pressure Systems • Uneven heating of the Earth’s surface causes differences in air pressure • Warm Air  Low Pressure System • Cold Air  High Pressure System

6. Weather Map: Fronts, Systems, Jet stream

7. Weather Fronts A front is the transition zone between two air masses of different density. Fronts extend not only in the horizontal direction, but in the vertical as well.

8. Cold Front & Air Masses

9. Global Wind Patterns

10. Cold Front on a Weather Map

11. Warm Front on a Weather Map

12. Occluded (Stationary) Fronts

13. Wind Patterns • Air flows from areas of high pressure into those of low pressure • Northern Hemisphere: air flow from areas of high to low pressure is deflected to the right; producing a clockwise circulation around an area of High pressure. • Counter-clockwise circulation around an area of Low pressure.

14. Wind Circulation Patterns

15. Weather Forecasting • Tools Used: • Thermometer (temperature) • Barometer (pressure) • Hygrometer (humidity) • Radar (storm & cloud movement) • Satellite imagery (storm & cloud movement) • National Weather Service Boise Site: • http://www.wrh.noaa.gov/boi/ • Weather Channel Site: • http://www.weather.com/

16. Weather Maps

17. Climate • Average of all weather conditions in area over a long time • Ex: temperature, precipitation • Climate is cyclically influenced by ocean currents & temperatures • El Niño& La Niña • These variations alter: • surface wind • surface ocean temperatures • deep ocean temperatures

18. Climate Cycles • Caused by Variations in ocean currents & temperatures • Cycles occur every 3-7 years • El Niño: characterized by unusually warm ocean temperatures in the Equatorial Pacific • La Niña: characterized by unusually coldocean temperatures in the Equatorial Pacific • Winter 2010/2011 is a moderate El Niño

19. Normal vs. El Niño Ocean Temperatures Unusually warm ocean temperatures in the Equatorial Pacific Wintersare warmer than normal in the Northern States & cooler than normal in the Southern States

20. Normal vs. La NiñaOcean Temperatures Unusually cold ocean temperatures in the Equatorial Pacific Winters are cooler than normal in the Northwest & warmer than normal in the Southeast

21. Cloud Characterization • Clouds are characterized by: • their height above the ground • Cirro • Alto • Nimbo • The type of cloud • Cirrus • Cumulus • Whether it forms layers = strata

22. Cloud Levels & Types

23. Cloud Levels & Types

24. Cloud Levels & Types