1. World Climates
Chapter 21, Section 2

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

4. Climates of the World

5. 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.

6. 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)

7. Rainforests vs. Savannas

8. 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.

9. 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

10. 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

11. Humid Mid-Latitude with Mild Winters

12. Humid Mid-Latitude with Severe Winters

13. 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.

14. 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

15. Extent of Dry Climate Zones

16. 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.

17. 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)

18. Two Types of Polar Climates

19. 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.

20. 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

21. Concept Check
How do highland climates compare with nearby lowland climates?
Highland climates are usually cooler and wetter than nearby places at lower elevations.

22. Assignment Read Chapter 21, Section 2 (pg. 592-599)
Do Chapter 21 Assessment #1-32 (pg )