Homework from last class:• Complete Chapter 10 review worksheets

• Study for Chapter 10 Quiz

• Bring May 12th Playland field trip forms and money ASAP!

▫ Due date to bring in forms and money is Monday, May 9th

• Read over class notes and check out the class blog: http://msoonscience.blogspot.com/

Chapter 10 Quiz•You will have ~15 minutes to write the quiz.

• Please write your multiple choice answers at the top of the test in the space provided.

Good luck!

Natural Causes of Climate Change

Chapter 11.1 pp. 464-480

Chapter 11.1 pp. 464-480

ClimateClimate: the average conditions of a region over ≥ 30 years.

• Includes clouds, precipitation, average temperature, humidity, atmospheric pressure, solar radiation, and wind.

• The size of a region can range from small (ex. an island) to large (ex. the entire planet).• Climate and geography combine to allow specific organisms to

grow

pp. 464 - 465

Biogeoclimatic zone: a region with distinct plants, soil, geography, and climate

Ex: BC has 14 distinct biogeoclimatic zones.

Past and Current ClimatePaleoclimatologists: people who study climates of the geological past

Fossils show what kind of environment was present Tree rings show evidence of growing seasons River sediments reveal types of rainfall Ice cores show past air condition and composition

Gases trapped in the ice, specifically CO2,reveal long-term atmospheric levels.

Fossils and sediment evidence show Earth’s climate has often changed drastically in the past.

Ex: 21 000 years ago, most of Canada and northern Europe was under glaciers.

pp. 466 - 467

Ice core data reveal CO2 levels for the past 650 000 years.

• Scientists have also tested levels of CO2 in the atmospheric air for the past 50 years.

pp. 466 - 467

Factors That Influence Climate:1) Composition of the Earth’s Atmosphere• Earth is a closed system.System: a group of parts that function together as a whole• Very little energy (except radiant energy) enters or leaves the system.

• Earth’s atmosphere is the outer boundary.

Greenhouse: a closed system that absorbs thermal energy.

Natural greenhouse effect: absorption of thermal energy by the atmosphere; allows for a narrow range of temperatures on Earth.

Greenhouse gases: gases in Earth’s atmosphere that absorb and trap radiation as thermal energy (ex: CO2)

• The more greenhouse gases, the higher the temperature of our atmosphere.

p. 468

2) Earth’s Tilt, Rotation, and Orbit• Earth’s tilt is responsible for seasons in northern hemisphere.

• Summer - tilted toward the Sun, decreasing angle of incidence.• Winter - tilted away from the Sun, solar radiation has a large

angle of incidence.• Earth’s tilt: ~22.3º - 24.5º • The greater the tilt, the more extremes in climate.

• Earth also “wobbles” as it rotates on its axis.• Axis changes changes angle of incidence of solar radiation.

• Earth’s revolution around the Sun is elliptical, not circular.• Variation in the Earth’s orbit changes its distance from the Sun.

p. 468 - 470

3) The Water CycleWater cycle: system of water circulation on, above, and below

Earth’s surface. • 70% of all greenhouse gases in the atmosphere is water

vapour.• When temperature increases, more water evaporates.• Two effects of increased water vapour in the atmosphere:

1) More solar energy may be absorbed by this greenhouse gas.

2) More solar energy may be reflected back out to space and never reach Earth.

p. 471

The water cycle stores and transfers large amounts of thermal energy.

4) Ocean Currents• Convection currents in oceans move large amounts of thermal

energy all around Earth.• Deep ocean currents (≥ 200 m) flow based on density

differences.• They behave like massive convection currents, with warm

water rising in the tropics and cold water from the higher latitudes replacing it.

pp. 471 - 473

Deep-ocean currents move cold, salty water below the surface and warm, less-salty water near the surface.

• Salinity of water also changes density.• Cold water (found at the poles) is more dense than warm water. • Salty water (found at the poles) is more dense than fresh water.• Large changes in ocean water density can reverse current

direction.

• Surface currents (0 - 200 m) are warmed by from solar radiation.• Upwelling occurs when cold, deep water rises into surface

currents. La Niña is an example of upwelling.

La Niña: cool water comes to the surface of the Pacific Ocean;causes warm winters in southeastern North America, and cool winters in the northwest.

El Niño is the reverse.

El Niño: warmer water on the surface of the Pacific Ocean results in warm winters in the Pacific Northwest and in eastern Canada.

pp. 471 - 473

Carbon cycle: maintains a balance of CO2 in the atmosphere.

Carbon sinks: a body or process that removes CO2 from the atmosphere and stores it. (Ex: plants, ocean, forests)

Carbon sources: a body or process that releases CO2 into the atmosphere. (Ex. rock weathering, burning fossil fuels or trees)

pp. 473 - 474

5) The Carbon Cycle• Carbon dioxide is a very important

greenhouse gas.

• More CO2 molecules than any other greenhouse gas (except H2O).

• CO2 traps infrared radiation from Earth’s surface, allows the average temperature of Earth to stay above freezing.

6) Catastrophic EventsCatastrophic event: large-scale disaster

• Large-scale disasters can quickly change atmospheric conditions.• Erupting volcanoes release ash and molten rock that absorb

radiation.• Released water vapour and sulfur dioxide (SO2) form sulfuric acid

(H2SO4) reflects solar radiation back into space.

p. 475

• Meteorites and comets are thought to cause dramatic changes.• Add dust, debris and gases in

the atmosphere.• May be responsible for some

of Earth’s largest extinction events.

• Debris reflects and absorbs radiation, causing the atmosphere below to cool.

Homework for next class:• Complete Check Your Understanding questions on

p. 481#s 1-8, 10, 12-15

• Bring May 12th Playland field trip forms and money ASAP!

▫ Due date to bring in forms and money is Monday, May 9th

• Read over class notes and check out the class blog: http://msoonscience.blogspot.com/

Works CitedImages taken from the following sources:http://blog.2012pro.com/predictions/polar-ice-is-melting-at-an-accelerated-pacehttp://www.flickr.com/photos/mike_smiths_flickr/2446977716/http://www.arctic.noaa.gov/essay_krembsdeming.htmlhttp://www.stelr.org.au/carbon-cycle/

Power Point Credit:McGraw Hill Ryerson, 2007.