Transcript Volcanoes and Igneous Activity Earth

Chapter 15: World Climates
The Atmosphere:
An Introduction to
Meteorology, 12th
Lutgens • Tarbuck
Lectures by:
Heather Gallacher,
Cleveland State University
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Climate Classification
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Köppen classification:
 This tool is based on mean monthly and annual
temperatures and precipitation.
 Criteria are unambiguous, simple to apply, and
are realistic.
 It recognizes five principal climate groups.
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Climate Classification

Köppen system:
 A Humid tropical—all months have mean temperature
greater than 18°C.
 B Dry—evaporation exceeds precipitation.
 C Humid midlatitude, mild winters—mean temperature
of the coldest month is above −3°C and lower than 18°C.
 D Humid midlatitude, severe winters—mean temperature
of the coldest month is less than −3°C, and the warmest
month is higher than 10°C.
 E Polar—summer-less, mean temperature of the warmest
month is lower than 10°C.
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Climate Classification
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Climate Controls: A Summary
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Climate Controls: A Summary
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Latitude:
 Variations in the receipt of solar energy are largely a
function of latitude.
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Land and Water:
 Marine climates are considered mild.
 Continental climates tend to be much more extreme.
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Climate Controls: A Summary

Geographic positioning and prevailing winds:
 The windward sides of continents are likely to have
marine climates.
 Leeward sides are likely to have continental climates.
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Climate Controls: A Summary
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Mountains and highlands:
 These topographic barriers trigger orographic
precipitation.
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Ocean currents:
 Cold currents cause aridity and fog.
 Warm currents cause warmer air temperatures.
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Climate Controls: A Summary
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Pressure and wind systems:
 Latitudinal shifting of pressure belts is responsible for
seasonal precipitation.
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World Climates—An Overview
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The Wet Tropics (Af, Am)
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The mean temperature is 25°C+.
They only cover about 10% of the Earth’s land area.
Total precipitation averages 200+ cm year.
It is wet all year.
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The Wet Tropics (Af, Am)
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Temperature characteristics
Precipitation characteristics:
 More than half of the days have rain.
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Tropical Wet and Dry (Aw)
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Aw is often called a savanna climate.
 The rain forest gives way to a tropical grassland.
 It has distinct wet and dry seasons.
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Tropical Wet and Dry (Aw)
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Temp characteristics:
 The daily range exceeds the annual range (3–10°C).
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Precipitation:
 The area has wet summers and dry winters.
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Tropical Wet and Dry (Aw)
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The monsoon:
 Alternating periods of rainfall and dryness are associated
with the monsoon.
 It typically refers to wind systems and their seasonal reversal.
 High pressure over the oceans in summer results in
wet conditions.
 High pressure over land in winter results in dry conditions.
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The Cw variant
 Cw climates are highland extensions of Aw.
 Cw areas are midlatitude extensions of the monsoon
realm.
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The Dry Climates (B)
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The Dry Climates (B)
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What is meant by “dry”?
 Yearly precipitation is less than the potential water loss
by evaporation.
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The Dry Climates (B)
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Subtropical desert (BWh) and steppe (BSh)
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The Dry Climates (B)
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Precipitation:
 In a BWh climate, precipitation is greatest in summer.
 In a BSh climate, precipitation is greatest in winter.
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Temperature:
 A lack of clouds makes for a greater temperature range.
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The Dry Climates (B)
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The Dry Climates (B)
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West coast subtropical deserts:
 These deserts are the Namib, Atacama, Sonoran,
and Sahara.
 Cold ocean currents just off shore have a dramatic
influence on the climate.
 These areas have cooler mean annual temperatures and
smaller daily ranges.
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The Dry Climates (B)
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Middle-latitude desert (BWk) and steppe (BSk)
 These are mainly caused by rain shadows.
 They have much lower winter temperatures and higher
annual ranges of temperature.
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Humid Middle-Latitude Climates
with Mild Winters (C)
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Humid Middle-Latitude Climates
with Mild Winters (C)
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Humid subtropical climate (Cfa)
 This climate is found on the eastern side of continents
between 25°–40° latitude.
 They have hot and humid summers and annual
precipitation of 100+ cm.
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Humid Middle-Latitude Climates
with Mild Winters (C)
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The marine west coast climate (Cfb)
 This climate is on the western sides of continents between
40°–65° latitude.
 They have mild winters and cool summers with
precipitation throughout year.
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Humid Middle-Latitude Climates
with Mild Winters (C)
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The dry summer subtropical (Mediterranean)
climate (Csa, Csb)
 These are typically located on the western sides of
continents between latitudes 30° and 45°.
 Temperature:
 The Csa type has warmer summers.
 The Csb type has cooler summers.
 Precipitation:
 Both average between 40 and 80 cm year and are
considered subhumid.
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Humid Continental Climates
with Severe Winters (D)
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Humid Continental Climates
with Severe Winters (D)
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Humid continental climate (Dfa):
 This is a land-controlled climate.
 Annual temperature ranges are great.
 Maximum precipitation occurs during the summer.
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Humid Continental Climates
with Severe Winters (D)
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The subarctic climate (Dfc, Dfd)
 This is often called the taiga climate.
 It is characterized by long, bitterly cold winters and short
warm/hot summers.
 This climate has approximately 50 cm of precipitation
per year.
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The Polar Climates (E)
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The Polar Climates (E)
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The tundra climate (ET)
 Large portions are characterized by permafrost.
 This climate has small amounts of precipitation with a
modest summer maximum.
 It has cool short summers (10°C).
 Tundras can also occur at higher elevations.
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The Polar Climates (E)
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The ice-cap climate (EF):
 This climate has no monthly mean temp above 0°C.
 The landscape is one of permanent ice and snow.
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Highland Climates
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These mountain climates (at elevation) are cooler
and usually wetter than those at lower elevations.
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End Of Chapter 15