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Climate Zones

ES10 Deirdre Scholar

earthobservatory.nasa.gov

World Climate Zones Map

Biomes Climate vs. Weather���•  Climate: long-term average (decades - centuries)

of weather (temperature & precipitation)

•  Weather: short term (hours – days) atmospheric conditions

•  1) temperature, 2) moisture, 3) pressure, 4) wind

•  Is Climate stable? Does it vary over time?

Climate is variable ���seasons

Summer/winter comparison in Iceland courtesy www.flickr.com/photos/gunnarfreyr

Climate is variable ���climate events (hurricanes, ENSO)

Hurricane Sandy image courtesy of earthobservatory.nasa.gov

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Climate varies over Earth’s history (Graph shows latter half of Pleistocene: past 1.6 m.y.)

Image courtesy of Pearson Publishing

Climographs •  At least 3 decades of temperature &

precipitation data •  Monthly averages

Image courtesy: southhill.vsb.bc.ca

Image Source: www.southhill.vsb.bc.ca

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

1.  Latitude & Insolation 2.  Atmospheric Circulation & Ocean Circulation 3.  Topography 4.  Proximity to water (Maritime & Continental climates) 5.  Elevation 6.  Storms

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%

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Absorption: opposite of Reflection

Solar radiation absorption From www.physicalgeography.net

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

Seasonal Shifts in Global Atmospheric Circulation

Image courtesy: southhill.vsb.bc.ca

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)

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Coriolis Effect •  Caused by Earth’s rotation

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

Ocean gyres

Gulf Stream

• Movement driven by Coriolis • N. Hem. Clockwise; S. Hem. counterclockwise

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

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 Orographic (mountain) Effect & Rain Shadows •  Mountains - air masses rise, cool, H2O condenses

–  Rain on windward side of mountains –  Dry on leeward side of mountains

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

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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

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

latitude •  Sharp vertical zonation of temperature (and

vegetation)

Earthobservatory.nasa.gov

Climate Zones

ES10 Deirdre Scholar

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 latitude (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 rainfall patterns? 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?