World Climates Chapter 21, Section 2
The Köppen Climate Classification System • The Köppen climate classification system uses mean monthly and annual values of temperature and precipitation to classify climates • The Köppen system has five principle groups: humid tropical climates, dry climates, humid mid-latitude climates, polar climates, and highland climates • All of these, except dry climates, are defined by temperature • Dry climates are classified according to the amount of precipitation
Climates of the World
Concept Check • What is the Köppen climate classification system? • The Köppen system uses mean monthly and annual values of temperature and precipitation to classify climates.
Humid Tropical Climates • Humid tropical climates are climates without winters • Every month in such a climate has a mean temperature above 18ºC • The amount of precipitation can exceed 200 cm per year • Wet Tropical Climate – high temperatures and much annual precipitation (Rainforests) • Tropical Wet and Dry Climate – temperatures and precipitation similar to the wet tropics, but experience distinct periods of low precipitation (Savannas)
Rainforests vs. Savannas
Concept Check • Describe the characteristics of humid tropical climates. • Humid tropical climates have no winters. Every month has a mean temperature above 18ºC and has a lot of precipitation.
Humid Mid-Latitude Climates • Climates with mild winters have an average temperature in the coldest month that is below 18ºC but above -3ºC • Climates with severe winters have an average temperature in the coldest month that is below -3ºC • Humid mid-latitude climates include: humid subtropical, marine west coast, dry-summer subtropical, humid continental, and subarctic
Humid Subtropical Climate – generally located on the eastern side of a continent and characterized by hot, sultry summers and cool winters • Marine West Coast Climate – found on the windward coasts from 40º and 65º latitude and dominated by maritime air masses; winters are mild, and summers are cool • Dry-Summer Subtropical Climate – located on the west sides of continents between 30º and 45º latitude; the only humid climate with a strong winter precipitation max • Subarctic Climate – found north of the humid continental climate and south of the polar climate; bitterly cold winters and short cool summers; highest annual temperature range
Humid Mid-Latitude with Mild Winters
Humid Mid-Latitude with Severe Winters
Concept Check • What type of climate does LA have? Explain. • LA has a dry-summer subtropical climate. It is on the west-side of the continent, located between 30º and 45º latitude, and experiences all of its precipitation in the winter.
Dry Climates • A dry climate is one in which the yearly precipitation is not as great as the potential loss of water by evaporation • Dryness is not only related to annual rainfall, but is also a function of evaporation • Evaporation is closely dependent upon temperature • There are two types of dry climates: arid (desert) and semi-arid (steppe) • The steppe is a marginal more humid variant of the desert, separating the desert from the humid climates • Dry climates exist as the result of the global distribution of air pressure and winds • Other dry climates are a result of rain shadows off of large mountain chains • Some of Earth’s driest climates occur where a cold ocean current affects the west coast of a continent
Extent of Dry Climate Zones
Concept Check • What defines a dry climate? • Both the amount of precipitation that falls and the amount that can be lost as the result of evaporation.
Polar Climates • Polar climates are those in which the mean temperature of the warmest month is below 10ºC • Polar winters are periods of perpetual night, making temperatures extremely cold • In the summer, temperatures remain cool despite the long days • Very little precipitation falls in polar regions • There are two types of polar climates: the tundra climate (treeless region) and the ice cap climate (permanent ice and snow)
Two Types of Polar Climates
Concept Check • What are the characteristics of polar climates? • Polar climates are extremely cold, even in the summer months. Very little precipitation falls in polar regions, and evaporation is limited.
Highland Climates • Highland climates are localized • They are much different than their surrounding climates • The conditions vary abruptly from one place to another • South-facing slopes are warmer than north-facing slopes • In general, highland climates are cooler and wetter than nearby areas at lower elevations
Concept Check • How do highland climates compare with nearby lowland climates? • Highland climates are usually cooler and wetter than nearby places at lower elevations.
Assignment • Read Chapter 21, Section 2 (pg. 592-599) • Do Chapter 21 Assessment #1-32 (pg. 609-610)
