Next lecture: Humans, Climate Change, and Ecological Responses

Ch 4 Variation in the Physical Environment

OBJECTIVES: What creates variation in climate and how does it explain the diversity and distribution of biomes?

• Build a model for proximal causes of global variation in climate and biomes

• How do features of the earth contribute to climatic variation?

• What are local effects on climate?• What are causes of temporal

changes in climate and biomes?

***What are 5 features of earth that affect climate?

1) Daily rhythm of dark and light?2) Temperature warmer at 0º than 90 º?3) Seasonal change in climate?4) Less variation in temperature in N than S?5) Winds to be diverted from N-S direction?

A) Rotates on axisB) RoundC) Tilt of 23º on axisD) Rotates around sunE) More land mass in N than S

***PRE-TEST: What feature of the earth causes:

Answers:1) Daily rhythm of dark and light? = A2) Temperature warmer at 0º than 90 º? = B3) Seasonal change in climate? = C + D4) Less variation in temperature in N than S? = E5) Winds to be diverted from N-S direction? = A + B

A) Rotates on axis B) Round C) Tilt of 23º on axisD) Rotates around sun E) More land mass in N than S

Overall conceptual model:• Solar radiation

• temperature

• wind and ocean currents • precipitation

***Why does temperature decline at higher latitudes?

***What accounts for differences in range of temperatures in N vs S hemisphere?

N.B. Specific heat is higher for water than land.

***What causes seasons and temporal variation in temperature? • latitudinal movement of the solar equator.

•Variation in temperature generates winds.(N.B. Mirrror of S and N hemispheres)

•Winds drive ocean currents and redistribute heat.

***What are latitudes of tropical rainforests and deserts? Why?

Why is it wet at 0° and dry at 30°?Hadley cells and ITCZ (inter-tropical convergence zone):

Solar equator (ITCZ) moves seasonally. • (so do belts of temp., wind, and rain)--->• causes seasonal variation in climate.

What causes deflections in air flow from N-S? Coreolis effect ; affects oceans too!

clockwise

counter-clockwise upwelling

Ocean currents 1) differ in N and S, 2) redistribute heat and moisture and 3) affect• marine environment on global scale

• climates on land.

Upwelling currents bring cold, nutrient-rich water to the surface --->support high productivity.

***Why are (most) deserts on W side of continents? What causes the Gobi desert in central Asia?Why does England have temperature deciduous forest rather than boreal forest?

Overall conceptual model:Solar radiation

• temperature

• wind and ocean currents • precipitation

***What determines local climate? • 1) Proximity to bodies of water

• Continental climates in interiors More arid More variable

• Maritime climates on coasts Less arid Less variable

2) Topography: gradients in mountains• Air cools as rises---> temp. decrease-->vegetation changes• (6-10°C drop for every 1000 m in elevation)

Why do mountains cause a rainshadow on their leeward side? How do they affect biomes?

How do mountain and wind directions affect this?

***Topography superimposes local variation on general climatic patterns. What causes these vegetation patterns?

Higher temperatures on S than N-facing slopes; >T --> > evaporation + < soil moisture

***What factors have changed existence and location of biomes through time?

• Continental drift

• Mountain building and rain shadows

• Changes in orbit, tilt, wobble of earth

• Climate variation

• past climate change

• present climate change

• Human alteration in land cover

OBJECTIVE: What creates variation in climate and how does it explain the diversity and distribution of biomes?

• Build a model for proximal causes of global variation in climate and biomes

• What features of the earth contribute to climatic variation?

• What are local effects on climate?• What are causes of temporal

changes in climate and biomes?

Vocabulary: Lecture 3; Chapter 4

Chapter 4 Variation in the Physical Environment

solar equator hadley cell intertropicalsubtropic high rain shadows convergence pressure belts upwelling (ITCZ)temperature profile spring overturn thermoclineepilimnion hypolimnion fall overturnfall (autumn)bloom riparian xericmesic adiabatic cooling life zonesoil* horizons weatheringpodsolization laterization Earth’s orbitalsolar irradiation* ocean circulation* parameters*

Example of exam question…

• Suppose you want to establish a lush,

thriving temperate garden and live near the

mountains.

• Major mountain ranges that run N-S in the temperate zone in the Northern hemisphere occur in north-central Russia, the eastern US, and the Pacific Northwest US.

• A. At which location and on which side of the mountain should you establish your garden?

• B. Explain your choice and why you did NOT choose the other two locations.

• C. Would your choice be different if you were choosing among mountain ranges in the temperate latitudes in the Southern hemisphere? Explain.