Climate Classification

Transcription

1 Chapter 15: World Climates The Atmosphere: An Introduction to Meteorology, 12 th Lutgens Tarbuck Lectures by: Heather Gallacher, Cleveland State University Climate Classification 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. 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. 1

2 Climate Classification Climate Controls: A Summary Climate Controls: A Summary Latitude: Variations in the receipt of solar energy are largely a function of latitude. Land and Water: Marine climates are considered mild. Continental climates tend to be much more extreme. 2

3 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. Climate Controls: A Summary Mountains and highlands: These topographic barriers trigger orographic precipitation. Ocean currents: Cold currents cause aridity and fog. Warm currents cause warmer air temperatures. Climate Controls: A Summary Pressure and wind systems: Latitudinal shifting of pressure belts is responsible for seasonal precipitation. 3

4 World Climates An Overview The Wet Tropics (Af, Am) 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. The Wet Tropics (Af, Am) Temperature characteristics Precipitation characteristics: More than half of the days have rain. 4

5 Tropical Wet and Dry (Aw) Aw is often called a savanna climate. The rain forest gives way to a tropical grassland. It has distinct wet and dry seasons. Tropical Wet and Dry (Aw) Temp characteristics: The daily range exceeds the annual range (3 10 C). Precipitation: The area has wet summers and dry winters. Tropical Wet and Dry (Aw) 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. The Cw variant Cw climates are highland extensions of Aw. Cw areas are midlatitude extensions of the monsoon realm. 5

6 What is meant by dry? Yearly precipitation is less than the potential water loss by evaporation. Subtropical desert (BWh) and steppe (BSh) 6

7 Precipitation: In a BWh climate, precipitation is greatest in summer. In a BSh climate, precipitation is greatest in winter. Temperature: A lack of clouds makes for a greater temperature range. 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. 7

8 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. Humid Middle-Latitude Climates with Mild Winters (C) Humid Middle-Latitude Climates with Mild Winters (C) Humid subtropical climate (Cfa) This climate is found on the eastern side of continents between latitude. They have hot and humid summers and annual precipitation of 100+ cm. 8

9 Humid Middle-Latitude Climates with Mild Winters (C) The marine west coast climate (Cfb) This climate is on the western sides of continents between latitude. They have mild winters and cool summers with precipitation throughout year. Humid Middle-Latitude Climates with Mild Winters (C) 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. Humid Continental Climates with Severe Winters (D) 9

10 Humid Continental Climates with Severe Winters (D) Humid continental climate (Dfa): This is a land-controlled climate. Annual temperature ranges are great. Maximum precipitation occurs during the summer. Humid Continental Climates with Severe Winters (D) 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. The Polar Climates (E) 10

11 The Polar Climates (E) 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. The Polar Climates (E) The ice-cap climate (EF): This climate has no monthly mean temp above 0 C. The landscape is one of permanent ice and snow. Highland Climates These mountain climates (at elevation) are cooler and usually wetter than those at lower elevations. 11

12 End Of Chapter 15 12