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

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

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

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

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

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

Assignment Read Chapter 21, Section 2 (pg. 592-599) Do Section 21.2 Assessment #1-8 (pg. 599)