1 / 21

Climate = Long term weather of a region

Ch. 24.7: Climate & Climate Change Objectives: 1. What factors affect climate? 2. What is El Nino & how does it work? 3. What causes ice ages? 4. How can scientists determine climate changes of the past?. Climate = Long term weather of a region. Depends on temperature & precipitation

veta
Download Presentation

Climate = Long term weather of a region

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Ch. 24.7: Climate & Climate ChangeObjectives:1. What factors affect climate?2. What is El Nino & how does it work?3. What causes ice ages? 4. How can scientists determine climate changes of the past?

  2. Climate = Long term weather of a region Depends on temperature & precipitation 6 Climate Regions: Tropical: Hot & wet or Hot w/ wet & dry seasons Dry: Desert Temperate marine: humid w/ mild winters Temperate continental: cold, snowy winters Highlands: mt. regions, cool & wet Polar: tundra & ice cap

  3. Climate: Factors Affecting Temperature 1. Altitude: Cooler @ higher altitudes 2. Latitude: • Cooler as you move away fr. equator. • Same latitudes have similar temps (solar radiation) 3. Distance from bodies of water: • Water moderates temps.  less variation • Landlocked areas – more extreme temps. (Hotter summers & colder winters) 4. Ocean currents can influence temps. Warm current  milder winters (Gulf stream brings warmer temps to UK) Cold current  cooler summers (California current brings cooler summer to San Francisco)

  4. Climate: Factors Affecting Precipitation. 1. Latitude Tropical air holds more moisture  rainy 2. Distribution of air pressure systems & global winds a. High Pressure Areas  Dry sinking air (30 N& S and poles) b. Low Pressure Areas  Moist rising air (0 & 60 degrees) b. Global Winds Wind from sea: Carry moist air  Wet climate Wind from land: Dry Climate 3. Mt. Barriers Mts. Force warm moist air from sea up  condenses & precips. on one side of Mt. Dry on other side

  5. Mt. Barriers (Orogenic Uplift) • WINDWARD SIDE • Warm air is pushed up by mountain, condenses, & precipitaties • WET • LEEWARD • Dry Air on opposite side • Desert - like

  6. Cascade Mts. – Washington State

  7. Orogenic Uplift Note how the western side of the Cascade Mts. (windward) are green with vegetation. The eastern side of the Cascades (leeward) are brown – due to a lack of vegetation (It’s dry on this side of the mountain).

  8. Global Pressure Systems Influence Climate

  9. Global Ocean Currents Gulf Stream Current – Circulates warmer tropical water north (Britian is warmer than it should be at its latitude)

  10. CH. 24.7 Climate Change: Seasonal: El Nino NaturalShort Range Change in Climate

  11. El Nino year

  12. El Nino: Periodic warming of water in the central & eastern Pacific Ocean (off coast of Peru) • Normally this water is VERY COLD due to an upwelling from the deep ocean. • Warm water affects atmosphere above water & trade winds slacken • Ocean currents in Pacific weaken or reverse direction • Result: Abnormal weather • When: Every 8 yrs (average)

  13. Climate Change: What Causes a Planet to Warm Up or Cool Down?

  14. Climate Change: Ice AgesNaturally Occuring, Long Term Ice Age: Colder than usual & glaciers cover larger portion of Earth’s surface as they advance fr. poles. When: 4 major ice ages in last 2 million years Last one ended 10, 000 yrs ago http://www.pbs.org/wgbh/nova/ice/chill.html http://courses.missouristate.edu/EMantei/creative/glg110/glaciers.html

  15. Icehouse vs. Greenhouse LOW 18O:16O HIGH 18O:16O ICE HOUSE = Ice present @ poles GREEN HOUSE= NO ice present @ poles

  16. Causes of Ice Ages 1. Milankovitch Cycles = Changes in incoming solar radiation due to variations in Earth’s orbit, tilt, or wobble. A. Change in “eccentricity” of orbit (How elliptical or circular our orbit is. Varies from 0 – 6% elliptical; Now: 1.7% elliptical) Cycle: 100 000 years More elliptical = more variation in climate = ice age B. Changes in Tilt Ranges from 22 – 24.5 degrees (Now 23.5 degrees) More Tilt = more seasonal variation = ice age Cycle: 41 000 yrs C. Changes in Wobble (direction of axis). N. Pole pointed toward or away from sun? Cycle: 23, 000 years www.atmo.arizona.edu/.../sec5/robust.html

  17. Causes of Ice Ages continued • 2. Volcanic Activity • Dust & ash can cause cooling in short term by blocking solar radiation (ice age) • Volcanic gases cause warming over long term (b/c they are greenhouse gases)

  18. 3. Changes in Solar Radiation (solar cycles)

  19. Ice Ages - Cause 55 Ma: Uplift of the Himalayas 4. Changes in continental arrangements (Plate tectonics)  can change ocean currents or air flow  can change climate

  20. Ice Ages: Cause 5. Change in Thermohaline Circulation (melting sea ice changes salinity of water; no sinking = slow down of THC)  change climate.

  21. Ancient Ice Age: Snow Ball Earth Ice covered Earth ~ 2.4 bya (end of Precambrian Time) Global temps: ~ - 74 F • 6. Biology Driven Ice Age = Snowball Earth • Weaker sun (30% weaker) + Arrival of photosynthesizing bacteria (removing CO2 from atmosphere) = ICE • ICE has high albedo --> more solar radiation reflected --> less energy absorbed --> MORE ICE • Volcanic GHG eventually warm planet up

More Related