Global ClimatesChapter 7

What is Climate? Climate is the condition of the lower

atmosphere in a particular region on Earth that is the average of at least 30 years worth of weather conditions in that place.

How is Climate Determined? Climatic elements considered when

determining the climate of a region:• Temperature• Moisture

Precipitation, humidity, cloudiness, surface water, evaporation conditions

• Related to temperature• Vegetation and soil conditions

May be used to determine climatic conditions where unclear

Additional Conditions Considered:

• Air pressure, wind, air mass movements, and global atmospheric circulations are also considered

These are related to latitude, altitude, ocean circulation, topography, and spatial distribution of land and sea

Also factored in:• Extreme weather conditions (flooding,

drought, hurricanes, tornadoes, etc.)

Why do we care? Climate and vegetation influence animal

habitats

Climate, vegetation, and animals together provide usable resources for humans

These conditions influence (but do not ultimately determine) the manner in which people may inhabit a region

Aristotle and Climate Classification

What about the Incas/Mayas/Aztecs? What about Murmansk, Russia?

Köppen-GeigerClimate Classification (1900-1940)

(Köppen only had five original categories—the Highland classification was added later)

Characteristics of the Major Climate Groups

A Tropical Humid—Avg. temp. of each month is > 64ºF (18ºC)B Dry—Evaporation exceeds precipitationC Mild Mid-Latitude—Average temperature of the coldest

month is between 27ºF (-3ºC) and 64ºF (18ºC)Average temp. of the warmest month is > 50ºF (10ºC)

D Severe Mid-Latitude—The warmest month is > 50ºF (10ºC)The coldest month is < 27ºF (-3ºC)

E Polar—No month has an average temp. > 50ºF (10ºC)H Highland—Significant climatic changes within short

horizontal distances due to altitudinal variations

24 Subclassificationsof the Climate Groups

f No dry season [German feucht, or “moist”]m Monsoon; a short dry season is opposed by heavy rains in other

monthsw Winter dry season (low-sun season)a Hot summersb Warm summersc Cool summersd Very cold wintersW Desert [German wüste, or “desert”]S Steppe (semiarid)h Low-latitude (subtropical) dry climate [German heiss, or “hot”]k Midlatitude dry climate [German kalt, or “cold”]s Summer dry season (high-sun season)T Tundra climatesF Ice cap climates (frost)

The Modified KöppenClassification System

Would you want to live here? This place exhibits a Csb climate The C = mild midlatitudes

• temperatures above 50ºF (10ºC) in summer• winters are short and mild, with little frost

The s = summer dry season (winter precipitation)

The b = warm summer• warmest summer months below 72°F (22°C)

Welcome to the lovely Mediterranean climate of Santa Barbara, California!

Modified Köppen Climate Map

Climograph

Temperature

Precipitation

Location

Climate classification

A Climates—In Brief

A Climates: Tropical Humid

Avg. temperature of each month exceeds 64ºF (18ºC)

Tropical Rain Forest

Tropical Monsoon

Tropical Savanna

Typical Daily Precipitation for Tropical Rain Forest (Af) Climates

Tropical Monsoon (Am) and Tropical Savanna (Aw)

B Climates—In Brief

B Climates: Dry

Evaporation exceeds precipitation

Arid DesertMidlatitude DesertSubtropical SteppeMidlatitude Steppe

Influence of the Subtropical Highs on Dry (B) Climates

The Atacama Desert: A Double Whammyof Ocean Currents andTopography

BSh—Subtropical (hot) Steppe (semi-arid)

BSk—Midlatitude (cold) Steppe (semi-arid)

BWh—Subtropical (hot) Desert

BWk—Midlatitude (cold) Desert

The Four Dry Climate Types

Subtropical (hot) Desert

Subtropical (hot) Steppe

Midlatitude (cold) Desert

Midlatitude (cold) Steppe

C Climates—In Brief

C Climates: Mesothermal

Avg. temp. of coldest month between 27ºF (-3ºC) and 64ºF (18ºC)Avg. temp. of warmest month > 50ºF (10ºC)

Humid Subtropical—no dry season, hot summerHumid Subtropical—dry winter, hot summerHumid Subtropical—dry winter, warm summerMarine West Coast—no dry season, warm summerMarine West Coast—no dry season, cool summerMediterranean—dry, hot summerMediterranean—dry, warm summer

Csb—Mediterranean(dry, warm summer)

Csa—Mediterranean(dry, hot summer)

C-climates

Cfa—Humid Subtropical

Cfc—Marine West Coast

D Climates: In Brief

D—Microthermal Climates

Humid Continental(hot or warm summers)Subarctic(cool summers or very cold winters)

D—Humid Continental

Winter In A Humid Continental Climate

D—Subarctic

Summer in Subarctic Climate Zone:Taiga (Eurasia)/Boreal Forest (Canada)

E—Polar Climates

Polar—tundraPolar—ice cap

E Climates—Tundra

Tundra: Lowland and Alpine

E Climates—Ice Sheet/Ice Cap

Ice Cap—The Arctic

Ice Sheet—The Antarctic

H—Highland Climates

Highland Climates

Tropical

Deserts

Mesothermal

Microthermal