Chapter 13: Global Climate By the end of this chapter you should: By the end of this chapter you should: Understand the controls of climate Understand the controls of climate Have an understanding of the Köppen system Have an understanding of the Köppen system

Global Temperatures Controls on climate: Controls on climate: - intensity of sunshine and its variation with latitude - distribution of land and water - ocean currents - prevailing winds - location of high and low pressure areas - mountain barriers - altitude

Fig. 13-1, p. 355

Global Temperatures “Bending” of isotherms near the continents “Bending” of isotherms near the continents Isotherms are west to east (solar radiation) Isotherms are west to east (solar radiation) Coldest temperatures over the interior of continents, warmest in subtropical deserts Coldest temperatures over the interior of continents, warmest in subtropical deserts

Global Precipitation Where air is rising, expect rain. Sinking air, expect a dry climate Where air is rising, expect rain. Sinking air, expect a dry climate ITCZ produces a tremendous amount of rain ITCZ produces a tremendous amount of rain Influence of orographic uplift and rain shadows Influence of orographic uplift and rain shadows

Fig. 13-2, p. 356

Climatic Classification - the Köppen System Tropical moist climates - average temp. Always above 64°F. Basically no winter Tropical moist climates - average temp. Always above 64°F. Basically no winter Dry climates – Evaporation and transpiration greater than precipitation Dry climates – Evaporation and transpiration greater than precipitation Moist mid-latitude climates with mild winters – warm-to-hot summers, mild winters. Ave. temps. coldest month between 64°F and 27°F Moist mid-latitude climates with mild winters – warm-to-hot summers, mild winters. Ave. temps. coldest month between 64°F and 27°F Moist mid-latitude climates with severe winters – warm summers and cold winters. Ave. temps warmest month between 50°F and 27°F Moist mid-latitude climates with severe winters – warm summers and cold winters. Ave. temps warmest month between 50°F and 27°F Polar climates – Extremely cold winters and summers. Ave temp between 50°F in warmest month. No summer. Polar climates – Extremely cold winters and summers. Ave temp between 50°F in warmest month. No summer.

Climatic Classification - the Köppen System Criticized because: Criticized because: Boundaries do not relate to natural boundaries in climatic zones Boundaries do not relate to natural boundaries in climatic zones System implies sharp changes. In reality, they are more subtle System implies sharp changes. In reality, they are more subtle

Fig. 13-6, p. 361

The Global Pattern of Climate

Tropical Moist Climates (Group A) Tropical wet (Af) Tropical wet (Af) Warm all seasons Warm all seasons Lots of rain Lots of rain N and S of equator to 15° to 25° N and S of equator to 15° to 25° Rainfall greater than 59 in. Rainfall greater than 59 in.

Tropical Moist Climates (Group A)

Tropical monsoon (Am) Tropical monsoon (Am) Precip drops below 6 cm for one or two months Precip drops below 6 cm for one or two months Annual precipitation amounts are similar to Af Annual precipitation amounts are similar to Af

Tropical Moist Climates (Group A) Tropical wet and dry (Aw) Tropical wet and dry (Aw) Distinct dry season Distinct dry season Jungle can not survive Jungle can not survive Savanna grass Savanna grass

Dry Climates (Group B) Arid (Bw) Arid (Bw) Deficient precipitation Deficient precipitation Sonoran and Mojave deserts (Rain shadow) Sonoran and Mojave deserts (Rain shadow)

Dry Climates (Group B) Semiarid (BS) Semiarid (BS) Transition between arid Transition between arid and more humid climates

Moist Subtropical Mid-latitude Climates (Group C) Humid subtropical (CfA) Humid subtropical (CfA) Humid and mild winters Humid and mild winters Eastern and western regions of most continents Eastern and western regions of most continents Hot, muggy summers Hot, muggy summers Mild winters Mild winters Snowfall is rare Snowfall is rare

Moist Subtropical Mid-latitude Climates (Group C) Marine (CfB) Marine (CfB) Summers are cool Summers are cool Long summers Long summers Mountains that parallel coast have effect Mountains that parallel coast have effect Clouds and drizzle Clouds and drizzle

Moist Subtropical Mid-latitude Climates (Group C) Mediterranean (Cs) Mediterranean (Cs) Dry summers, influenced by the subtropical highs Dry summers, influenced by the subtropical highs

Moist Continental Climates (Group D) Warm to cool summers, cold winters Warm to cool summers, cold winters Winters are severe (cold, snowstorms) Winters are severe (cold, snowstorms) Controlled by large landmasses (N.H.) Controlled by large landmasses (N.H.) Coldest month average below 27°F Coldest month average below 27°F Can still have trees Can still have trees

Moist Continental Climates (Group D) Humid continental with hot summers (Dfa) Latitude 40°N to 50°N Precipitation between 20 and 40 in. Hot summers (exceed 90°F)

Moist Continental Climates (Group D) Humid continental with cool summers (Dfb) Humid continental with cool summers (Dfb) Cooler and less humid than Dfa Cooler and less humid than Dfa Hot spells shorter Hot spells shorter Winters long, cold windy Winters long, cold windy Large temperature range like Dfa Large temperature range like Dfa

Moist Continental Climates (Group D) Subpolar (Dfc) Severe winters, short summers Severe winters, short summers Only 1 month w/ mean temp > 50°F Only 1 month w/ mean temp > 50°F Large temperature ranges Large temperature ranges Precipitation is light Precipitation is light Boreal climate Boreal climate

Polar Climates (Group E) Always low temperatures One type has at least one month above freezing…one doesn’t

Polar Climates (Group E) Polar tundra (ET) Polar tundra (ET) Always low temperatures (warmest month < 50°F Always low temperatures (warmest month < 50°F Permafrost is abundant/Low precipitation amounts Permafrost is abundant/Low precipitation amounts Tundra vegetation (mosses, scattered wooded areas Tundra vegetation (mosses, scattered wooded areas Large temperature ranges Large temperature ranges

Polar Climates (Group E) Polar ice caps (EF) Polar ice caps (EF) Average temp always below freezing Average temp always below freezing No plants No plants Covered in snow and ice Covered in snow and ice Little precipitation Little precipitation Katabatic winds present Katabatic winds present

Highland Climates (Group H) Altitude effects are similar to latitude effects Altitude effects are similar to latitude effects