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Global Climate

Chapter 17Chapter 17April 23, 2009

Climatic Controls• Climate controls

Climatic Controls

– Latitude– Land and waterLand and water– Ocean currents

P ili i d– Prevailing winds– Pressure cells– Mountain

barriers– Altitude

This shows average annual sea-level temperatures in oF

Regions of Rising & Sinking AirRegions of Rising & Sinking Air

Global patterns of temperature and precipitation areprecipitation are affected by global cells ofglobal cells of rising and sinking air, which run meridionally north to southnorth to south

Observed Precipitationp

N th t th tt f i i d i ki i h l t di tNorth-to-south patterns of rising and sinking air help to predict precipitation, but zonal variation in land masses and ocean currents create deviations from these predictions.

Topographic Controls on ClimateTopographic Controls on Climate

Westerly winds blowing moist air from the Pacific Ocean encounter several mountain ranges that create patterns of rising air and precipitation followed by sinking air and warm dry rain shadows.

Climate ClassificationsClimate ClassificationsTh A i t G k• The Ancient Greeks– Tropical, temperate, and polar zone– Not enough zones to describe climate

• The Köppen System– Waldimir Köppen– Related vegetation and climate in order to predict g p

climate types in areas without climate data• The Thornthwaite Systemy

– P/E ratio, P/E Index– Potential Evapotranspirationp p

Köppen Climate Classification GroupsKöppen Climate Classification Groups

• A = Topical Moist: no winterB D P t ti l t i ti• B = Dry; Potential evapotranspiration > precipitation

• C = Moist Mid-Latitude with mild winterD M i t Mid L tit d ith i t• D = Moist Mid Latitude with severe winter

• E = Polar: cold, T<10°C,• H = Highland

More ClassificationsMore ClassificationsAf Tropical rain forest Dfa humid continental long hot Af Tropical rain forestAm Tropical monsoonAw Tropical wet and dry

Dfa humid continental long hot summer

Dfb humid continental long cool Aw Tropical wet and dryBW Arid desertBS Semi-arid

gsummer

Dfc subpolar cool short summerBS Semi aridCfa Humid subtropicalCfb Cfc Marine

Dw Dry winterET polar tundraCfb Cfc Marine

Cs Mediterranean dry summer

EF Polar ice capH Highlandsummer

Cw Dry winter

g

AfAfIquitos Peru

Tropical wet

Iquitos, Peru

wet climate

AwAwTimbo, Guinea

Tropical wet and dry climate

BWhBWh

Arid desertArid desert climate

Phoenix, AZ

BWh

Arid desertArid desert climate

6

8

ion (in

)

4

thly Precupitat

2

Anv

erage Mon

t

Average annual precipitation 10.6 cm (4.19 inches)

0

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

A

BSkBSk

Dry, semi-id l

Denver, COarid, cool climate

CfaCfa

Humid sub- Mobile, ALtropical climate

CfbCfb

Humid marine Port Hardy, climate Canada

Csb Csa

Coastal Mediterranean Interior Mediterranean

DfcDfc

Moist C ti t Fairbanks AKContinental Sub polar

Fairbanks, AK

polar

ETET

Polar tundraPolar tundra

Barrow, AKBarrow, AK

Elevation Controls on ClimateElevation Controls on Climate

Ascending a mountain brings changes in temperature and precipitation, and so to will bring changes in vegetation types and micro-climates, as illustrated i thi k t h th t f l d t t d d i h tin this sketch that moves from grassland to tundra and icecap across a short distance of 180 km, and up a steep elevation of 4 km.

Extremes from last 30 yearsExtremes from last 30 years

http://www.ncdc.noaa.gov/oa/climate/research/2007/dec/extreme-cities.html

Extremes from last 30 yearsExtremes from last 30 years

Climate Anomalies 2008Climate Anomalies 2008

From NCDChttp://www.ncdc.noaa.gov/img/climate/research/2008/ann/significant-extremes2008.gif

Daily Climate SummaryDaily Climate SummaryThis is the climate summary for WednesdayReport published Thursday

Climate database

p p y

Indicates normal temperatures and precipitation and records

Annual Precipitation 2008Annual Precipitation 2008

Total Precipitation map from:

Jan to Dec 2008 Precipitation % of Normal map:http://www.ncdc.noaa.gov/img/climate/research/2008/dec/precip.dfn.ytd-cont-200812.gif

Total Precipitation map from:http://www.cpc.noaa.gov/products/analysis_monitoring/regional_monitoring/us_12-month_precip.shtml

Drought TrackingDrought Tracking

Cloud ClimatologyCloud Climatology

• International Satellite Cloud Climatology Projectj

Average January Cloud Coverg y

Based on 2002-2006 MODIS Aqua daytime imagery