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WEATHER

WEATHER. Meteorology - Study of weather. I. Basic Principles. A. Earth in space 1. earth – spins on own axis & completes one rotation every 24 hrs. (causing day & night). 2. earth – takes 1 year to complete 1 orbit ( revolution ) around the sun.

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WEATHER

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  1. WEATHER Meteorology - Study of weather

  2. I. Basic Principles A. Earth in space 1. earth – spins on own axis & completes one rotation every 24 hrs. (causing day & night)

  3. 2. earth – takes 1 year to complete 1 orbit (revolution) around the sun

  4. 3. earth’s axis tilted: 1 hemisphere receives more light causing summer; less light – winter a. equinox – sun directly overhead on equator; - autumnal equinox – Sept. 21 - spring (vernal) equinox – March 21

  5. b.) solstice –when the sun’s overhead on: - Tropic of cancer – summer solstice: June 21st - Tropic of capricorn – winter solstice: Dec. 21st

  6. Tilt/Seasons – 0:50

  7. B. Atmosphere - 310 miles 2000 oC or higher -50 miles/ -120 oC -31 miles/ 0 oC -ozone layer - 11 miles/ -80 oC - weather takes place

  8. 1. troposphere – lowest region where weather occurs; contains water vapor & clouds; contains 78.08 % (78%) N2 and 20.94% (21%) O2 2. stratosphere – warmer due to ozone (O3) layer; absorbs UV radiation

  9. Our Atmosphere – 2:40

  10. C. 3 causes of weather – pressure, temp., precip.

  11. II. Pressure - downward force exerted by the weight of the air; greatest at sea level; measured by the weight of the air (barometer)

  12. A. Higher pressure has a higher temp.; - less pressure - cooler; ex. mt., heat pump - less pressure – lets air rise faster to make winds

  13. B. Wind – air moves from a high to low pressure (H  L)

  14. Pressure moves from H  L

  15. C. High pressure systems (H) – move clockwise & generally result in fair weather D. Low pressure systems (L) – move counterclockwise & generally result in unsettled (bad) weather

  16. E. Isobars – lines on weather maps to connect similar pressures

  17. Air Pressure – 2:11

  18. High/Low Pressure – 1:00

  19. III. Temperature - Measure of amt. of energy of the molecules; caused by sun; measured by thermometer

  20. A. Sunshine 1. warmth & light 2. photosynthesis – makes food & O2 3. helps in evaporation/transpiration - drives the water cycle

  21. 4. creates optical effects a. reflection – light bounces off a surface; ex. oceans reflect light - albedo effect – reflectiveness of a surface; ex. snow & white shirt – high albedo b. refraction – light moving from 1 medium to another, causes the speed to change & bends the light; ex. mirage

  22. REFLECTION REFRACTION

  23. B. Conduction 1. Heat striking an object transfers some energy to object; ex. sand gets hot on feet 2. materials vary in amount of heat absorbed (specific heat capacity) before temp. increases; ex. metal heats up faster than wood

  24. C. Density of different temp. 1. heat – less dense, warm air rises 2. cold – more dense, cold air sinks 3. convection current – warm fluid that is less dense & rises; ex. in atmosphere, ocean, under the crust

  25. D. Isotherms – bands used on weather maps to connect similar temps

  26. Sunlight & Solar Energy – 1:49

  27. E. Temperature Fronts 1. cold front – barometer falls – low; large clouds form; violent storms – thunder & lightning

  28. 2. warm front – less violent storms; don’t move as fast but last longer; as warm air rises, it cools & condenses  precip.

  29. Fronts – 3:17

  30. IV. Water A. Importance? Available B. H2O & the weather – can occur in all 3 states at ordinary temps.

  31. gas boiling  condensation  liquid melting  freezing  Solid (ice)

  32. - takes a great deal of energy to change the temp. - oceans fluctuate less than land - cold/warm ocean currents affect the air temp. above it

  33. C. Water Cycle

  34. - 9 places water found: clouds, groundwater, oceans, lakes, rivers, soil, plants, animals, glaciers

  35. D. Clouds and Fog 1. Relative humidity: 100% - air becomes saturated; fog – ground level; clouds – above ground; warm air holds more moisture than cold air 2. water vapor (normally) condenses only onto a surface; ex. Dust, soot, sulfate - the bigger the particle the bigger the droplet; called CCN – cloud condensation nuclei

  36. E. Rain - water droplets more than .5 mm across collects around CCN; when too heavy they fall as rain

  37. F. Snow & Sleet 1. Snow – water freezes to form crystals 2. Sleet – ice pellets smaller than 5 mm in diameter

  38. G. Hail, thunder, lightning – caused by rising warm air 1. Hail – rising air currents carry water droplets up & they freeze. This process continues & refreezes in layers. When heavy enough to overcome air currents, they drop

  39. 2. Thunder & lightning – rising air currents create convection currents – hot air rises at center while cold air sinks at sides - thundercloud: has + electrical charge at top & - charge at the bottom. Eventually huge sparks flash between the charges, neutralizing them  lightning. - Lightning releases so much energy – that air which passes through it explodes  thunder

  40. - the difference in electrical charge can be more than 305 volts/ft.

  41. What are Thunderstorms? – 0:43

  42. How do Thunderstorms form? – 2:41

  43. Updrafts & Hail – 1:10

  44. H. Dew & water - Clear skies cause quick cooling, chilling the air next to it. Water vapor condenses on surface  dew (dew point reached)

  45. THE END!

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