Ch. 21 Climate
21.1 Factors That Affect Climate
Factors that Affect Climate
 Affect the 2 most important elements of climate
 Temperature & Precipitation
 Latitude
 Elevation
 Topography
 Water Bodies
 Atmospheric Circulation
 Vegetation
Latitude
 Distance N or S of the equator
 As latitude increases, the intensity of solar energy
decrease
 The sun’s rays are most intense in the tropics
why…bc the region is at a right angle to the sun
 Tropical Zones
 Temperate Zones
 Polar Zones
Elevation
 Height above sea level
 Air temp. decreases w/ elevation
 The higher the elevation is, the colder the
climate is
 Elevation also determines how much
precipitation an area gets
Topography
 Topographic features such as mountains
play an important role in the amount of
precipitation that falls over an area.
 Rain Shadows – the dry area on the
leeward side of the mountain
Water Bodies
 Large bodies of water such as lakes & oceans
have an important effect on the temp. of an
area bc the temp. of the water body influences
the temp. of the air above it
 Think back to last unit…how does land heat &
cool differently than water?????
Atmospheric Circulation
 Global winds influence climate bc they
distribute heat & moisture around the
Earth
 HEAT BALANCE
 Warm air to the poles & cool air to the
equator
Vegetation
 Certain types of plants only can grow in
particular climates
 Vegetation can affect both temp. &
precipitation patterns in a particular area
 Vegetation influences how much of the sun’s
energy is absorbed & how fast this energy is
released (affects temp.)
 Transpiration (influences precipitation)
REVIEW REVIEW REVIEW
 How does latitude affect climate?
 How does elevation affect climate?
 How does a mountain range affect climate?
 How do bodies of water affect climate?
 What effect do global winds have on
climate?
 Describe how vegetation affects climate?
21.2 World Climates
The Koppen Climate Classification
System
 Uses mean monthly & annual values of temp.
and precipitation to classify climates
 Classifies it into climate regions
 5 principle groups: humid tropical, dry
climates, humid mid-latitude, polar climates, &
highland climates
Humid Tropical Climates
 Climates without winters
 Every month has a mean temp. above 18 oC
 Amt. of precipitation exceeds 200 cm
 2 types of humid tropical climates:
 Wet Tropical
 Tropical Wet & Dry
Humid Tropical Climates
Wet Tropical
 Tropical Rainforest
 High temps. & a lot of
precipitation
 Sun’s rays are always high
 Winds blow over causing
the warm, humid unstable
air to rise cool and
condense and then fall as
precipitation
Tropical Wet & Dry
 Bordering the wet tropics
 Have temps. & total
precipitation close to
those in wet tropics, but
this climate experiences
times of low precipitation
Humid Mid-Latitude Climates
 Include climates with mild winters & severe
winters
 Climates with mild winters have an avg. temp.
in the coldest month that is below 18 oC but
above -3 oC
 Severe winters have an avg. temp. in the
coldest month that is below -3 oC
Humid Mid – Latitude w/ Mild
Winters
 3 types: humid subtropical, marine west coast, &
dry-summer subtropical
 Humid subtropical – 25-40 degrees latitude on the
Eastern side of the continent
 Marine West Coast – 40-65 degrees latitude N & S
 Dry-Summer Subtropical – 30-45 degrees latitude
Humid Mid-Latitude w/ Severe
Winters
 2 types: humid continental climates &
subarctic climates
 Continental landmasses strongly influence
both climates
 Absent in the Southern Hemisphere
Dry Climates
 Yearly precipitation is not as great as the
potential loss of water by evaporation
 Evaporation is dependent on temperature
 2 types of dry climates: arid or desert & semiarid or steppe
 Result of global distribution of air pressure
and winds
Polar Climates
 Mean temp. of the warmest month is below 10 oC
 Very little precipitation
 Evaporation rates are also low
 2 types: Tundra Climate & Ice Cap Climate
 Tundra is a treeless region most in N. Hemisphere
 Ice Cap Climate does not have a single monthly
mean above 0 oC & has little vegetation &
permanent ice and snow
Highland Climates
 Localized (much different from climates in
surrounding areas)
 Vary from place to place
 In general they are cooler & wetter than
nearby areas at lower elevations
REVIEW REVIEW REVIEW
 Describe the Koppen climate classification
system.
 How do highland climates compare with
nearby lowlands?
 Can tundra climates exist at low latitudes?
Why or why not?