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Climate Zones�

ES10�

Deirdre Scholar

Biomes

Weather vs. Climate�•  Weather: short term (hours – days) atmospheric

conditions�•  What are the 4 conditions (components) of weather?�•  1) temperature, 2) moisture, 3) pressure, 4) wind�

•  Climate: long-term average (decades - centuries) of weather (temperature & precipitation)�

•  Climate is variable �–  seasons �–  climatic events (e.g. El Nino) �–  over geologic time�

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Climographs •  At least 3 decades of temperature &

precipitation data •  Monthly averages

Source: www.southhill.vsb.bc.ca

What controls locations of �climate zones (& biomes)?�

1.  Latitude & Insolation ��

2.  Ocean & Atmospheric circulation�

3.  Topography�

4.  Proximity to water (Maritime & Continental climates)�

5.  Elevation�

6.  Storms�

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1) Latitude & Insolation •  Angle of incidence: angle sun’s rays strike E’s

surface. • Insolation: Incoming solar radiation

– Tropical: concentrated Polar: spread out

Albedo (reflectivity)

Source: Earthobservatory.nasa.gov�

Snow & Ice 80 - 85% Clouds 70 - 90% Water (low sun angle) 50 - 80% Sand 20 - 30% Forest 5 - 10% Water (high sun angle) 5% Dark Soil 3%

Absorption: opposite of Reflection

Solar radiation absorption �From www.physicalgeography.net

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2) Atmospheric & Ocean Circulation •  Hadley Cells Rising air @ equator, Inter-tropical Convergence

Zone/ITCZ (Doldrums); evaporative cooling

•  Trade Winds

Seasons�

www.classzone.com�

Cause: Tilt of Earth’s axis (23.5)�

�changes location of concentrated insolation & duration of daylight hours�

Seasonal Shifts in Global Atmospheric Circulation

southhill.vsb.bc.ca

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Why are the hottest places on earth not in the tropics?

Descending air @ 30°N & S latitudes – Compressional heating; high pressure & clear skies�

Adiabatic Cooling & Warming •  Warm air rises---> air

expands & cools •  Cool air sinks� air

compresses & warms •  No heat is added or

removed (adiabatic) •  In atmosphere:

– Air rises=cools – Air descends=warms

Coriolis Effect •  Caused by Earth’s rotation

–  Unattached moving objects (atmosphere & oceans) follow curved paths •  right in northern hemisphere; left in southern hemisphere

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Ocean gyres

Gulf Stream

• Movement • N. Hem. Clockwise; S. Hem. counterclockwise

Ocean Currents influence climates on east & west coasts of continents @ same latitude

Chile is cooler and drier

Brazil is tropical

currents are warm on east coasts cold along west coasts of continents

3) Topography & Climate Orographic (mountain) Effect and Rain Shadows

•  Mountains - air masses rise, cool, H2O condenses –  Rain on windward side of mountains –  Dry on leeward side of mountains

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Topographic Barriers/mountains Rain on windward side of mountains Dry on leeward side of mountains Different climates on same island

Earthobservatory.nasa.gov�

Rain Shadows in California •  4 mountain ranges

between the SC and Death Valley

•  Death Valley –  Hottest, driest

place in North America

4) Proximity to Water; Maritime & Continental Climates

•  Hottest and coldest places on Earth are inland/continental interiors –  Antarctica -128.6° F –  Al’Azizivah, Libya 136° F –  Death Valley, CA 134.1 ° F

Earthobservatory.nasa.gov�

http://en.wikipedia.org/wiki/File:DeathValleyDunes4.jpg

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5) Elevation; Mountain Climates •  Controlled by elevation & angle of sun exposure NOT

latitude •  Sharp vertical zonation of temperature (and

vegetation) •  Abrupt changes in weather--be prepared! •  Plays important role in mountain climates

Earthobservatory.nasa.gov�Earthobservatoratorvaatorvatoraaatoratoratoratorvavaaaatoravatororatorvatorvatorvatottortooooratooratorortorvatovatoratortorooatorovatoratorortortorvatoatotortotortorrtoatoroaat rrratot rrtorttorrory.nasy.nasy.nasny.nasy.nay.nay.nasy.nasy.nasy nay nasy.nasy.nasy.nasy.nasy.nasy.nasy.nay nay.nay.na.nasasyy.nay.nasyy.nn.nnnay nay.nasy.nay nasy.nasyy.y.nyy.nnnnaa.nasy.ny.nay.nayyy syy nny.nay.nn a.goa.gova goa.goaa.gova ga.gov.goa.gov.govga.gova goa.govgoa.govgovvva goa.goa.goa.goaa.goa gogooa gova.gova.govva goaa gogoa.govgovogoa.googoa.goa.goa.go.goa.go.govoa.goa.govvvaa.gogovaaaa.gogg vvg

Review questions for Climate Zones Lecture�1.  Describe the main differences between weather and climate--what controls them? �2.  Define angle of incidence, insolation and albedo. What is the relationship

between latitiude (distance from equator), angle of incidence, insolation and average temperatures?�

3.  Which surfaces have high albedo, which have low albedo? �4.  What kinds of climate should we expect at the equator (0°), 30°N&S? �5.  Why do wind and ocean currents flow in a curved path? Name of effect?�6.  What causes seasons? How do seasons change location of ITCZ etc.?�7.  What temperature patterns exist with ocean currents on east and west coasts of

continents? Give an example of how ocean water temps & climates vary at the same latitude & continent along opposite coasts?�

8.  Orographic Effect & Rainshadows: Why are the eastern facing (leeward) slopes of California’s mountain ranges drier than the western facing (windward) slopes? Explain the formation of Death valley’s climate.�

9.  Mountain climates: controlled by? Characteristics?�10.  If there’s time…..�11.  What is upwelling? How does it contribute to the formation of fog & fisheries

along the CA coast?�12.  What is ENSO? Where are it’s effects most intense? What impacts does it have

on upwelling, winter storm activity and coastal erosion in CA?�

If there’s time….

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Upwelling along west coasts of North and South America

Upwelling and fog formation along California Coast

www.gsfc.nasa.gov/topstory/20021016westbloom.html

ENSO El Niño Southern Oscillation

•  Intertropical Convergence Zone (ITCZ: where trade winds meet), shifts southward--below equator

•  Intense eastward flow of equatorial countercurrent in Pacific Ocean

•  Warm water flows towards continents of N.A. and S.A.

•  Ocean climate changes persist for 12-18 months

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Pacific Surface

Flow

Sea Surface Temperature and Water Temperature Profile

January 1997 y

SST and Temp. Profile November 1997

Red is 30 degrees C and blue is 8 degrees C. g g

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SST and Temp. Profile March 1998

Sea Level Measurements from San Francisco 1900 -

1999

Seabright Beach 10/97

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Seabright Beach 2/98

Debris Flows

Impacts of ENSO

•  Along west coasts of N.A. and S.A. –  Changes to wind patterns

•  Upwelling reduced or cut off completely

–  Coastal Erosion and flooding dramatically increased by: •  Rise in SL due to thermal expansion of water •  Heavy rainfall •  Severe storm activity •  Large wave events

–  75% of all coastal erosion in CA occurs during El Niño winters

•  Severe droughts in Australia and Indonesia

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climate zone formation

Equator: TROPICAL 30° N&S: DESERT 60° N&S:TEMPERATE 90° N&S Poles: POLAR