AOSC 200
Lesson 22
Past and present climates
• weather - short time fluctuations
• climate – long-term behavior
- location
- time
- average and extremes
• climate controls
- latitude
- elevation
- topography
- proximity to large bodies of water
- atmospheric circulation
THE CHANGING CLIMATE
• Climate involves more than just the atmosphere.
• Climate may be broadly defined as the long-term
behavior of global environmental system
• “To understand fully and to predict changes in the
atmospheric component of the climate system. one
must first understand the sun, oceans, ice sheets,
solid earth, and all forms of life"
• Thus we talk about a climate system consisting of
the atmosphere, hydrosphere, solid earth,
biosphere and cryosphere.
• Climate system involves the exchange of energy
and moisture among these components
Locations close
together can have
different climates.
Cities at the same latitude can have different climates
The three convective cells produce different climates. These
cells move with the seasons producing sud-climates
Fig. 14-3, p. 414
CLIMATE ZONES
•
•
•
•
•
•
•
VLADIMAR KOPPEN ZONES
TROPICAL MOIST – A
DRY – B
MOIST WITH MILD WINTERS – C
MOIST WITH SEVERE WINTERS – D
POLAR – E
HIGHLAND – H
World map of the Kopper climate classification scheme
Fig. 14-2, p. 413
Tropical Humid Climates - A
• High mean monthly temperature, at leaest
18.3 C.
• Rage of temperature is small, less than 10
degrees.
• Divided into three sub-types
• Tropical wet climates (Af)
• Tropical wet and dry climates (Aw)
• Tropical monsoon climates (Am)
Tropical Humid Climates
Iquitos, Peru (Af), Pirenopolis, Brazil, Aw, Rochambeau
French Guiana, Am
Fig. 14.4
Tropical rain forest near Iquitos, Peru, (Af)
Baobob and Acacia trees in grassland
savanna (Aw)
Dry Climates
• Evaporation plus transpiration exceeds
precipitation. Descending branch of the
Hadley cell.
• Mainly over land, diurnal variation larger
than annual variation.
• Two subtypes
• Steppe or semi-arid (BS)
• Arid or desert (BW)
• BSh and BWh are warm dry climates
• BSk and BWk are cold dry climates
Dry Subtropical Climates
Dakar, Senegal BSh, Cairo, Egypt BWh
Fig. 14.5
Warm Dry Climates
San Diego, Calif.BSk, Santa Cruz, Argentina, BWk
Fig. 14.6
Rain streamers are common in warm dry climates.
Rain evaporates before it reaches the ground.
Creosote bushes and catcus
in the arid southwestern
deserts (BWh)
Steppe grasslands of western North America (BS)
Moist Subtropical and Midlatitude
Climates
•
•
•
•
•
•
Characterized by humid and mild winters.
Lie between the tropics and mid-latitudes
Three major subgroups
Marine West Coast Cfb and Cfc
Humid Subtropical Cfa and Cwa
Mediterranean Csa or Csb
Marine West Coast Cfb, Cfc
Bergen, Norway Cfb, Reykjavik, Iceland Cfc
Fig. 14.7
Humid Subtropical Cfa, Cwa
New Orleans, Louisiana, Cfa, Hong Kong China, Cwa
Fig. 14.8
Mediterranean , Csa, Csb
Lisbon, Portugal, Csa, Santiago, Chile, Csb
Fig. 14.9
Mediterranean-type climate of North America.
Chaparral : foothill pine, chamise and manzanita.
Severe Midlatitude Climates, D
• Tend to be located in the eastern regions of
continents.
• Temperature range is generally greater than seen
in the western climates (C)
• To be classified as D the average cold temperature
must be less than -3 C, and the average summer
temperature must exceed +10 C.
• Two basic types
• Humid Continental (Dfa/b and Dwa/b)
• Subarctic (Dfc/d and Dwc/d)
• a,b,c, - hot summers, d - severe winter and cold
summer
Humid Continental
Vladosvostok, Russia Dwb, Fargo, North Dakota, Dfb
Fig. 14.10
Adirondack Park - humid continental
climate (Dfa)
Subarctic
Fairbanks, Alaska, Dfc, Verkhoyansk, Siberia, Dfd
Fig. 14.11
Coniferous forests occur where winter
temperatures are low and precipitation is
abundant (Dfc)
Polar Climates, E
• Occur poleward of the Arctic and Antarctic circles
• Mean temperatures are less than 10 C for all
months.
• Annual precipitation is less than 10 inches.
• Two polar climate types are identified
• Tundra (ET) and Ice Caps (EF)
• EF have essentially no vegetation
Polar Climates, E
Barrow, Alaska, ET, Eismitte, Greenland, EF
Fig. 14.12
Tundra vegetation in Alaska – sedges and
dwarfed wildflowers (ET)
Highland climate (H)