Chapter 3Section 3 World Climate Patterns
Objectives: • Identify different climate zones • Explain Latitudes Effect of Climate
Climate Regions • Geographers often divide the earth into climate regions- tropical, dry, mid-latitude, and highlands. • Climates vary within these major regions, so they are divided into even smaller, more specific regions. • Each of these regions has its own characteristic soils and natural vegetation.
Tropical Climates • Found in or near the low latitudes- the Tropics. • The two most widespread types of tropical climates are tropical rain forest and tropical savanna.
Tropical Rain Forests • Temperatures average about 80⁰ F and it rains daily. • Yearly rainfall averages about 80 inches, resulting in lush, canopied vegetation, although the continual rain tends to draw out nutrients from the soil. • The world’s largest tropical rain forest is in the Amazon River basin, but similar climates and vegetation exist in other parts of South America, the Caribbean area, Asia, and Africa.
Tropical Savanna • Climates have dry winters and wet summers, accompanied by high temperatures year round. • In the dry season, the ground is covered in coarse grass, and fewer amounts of vegetation exist in this area. • Tropical Savannas are found in Africa, Central and South America, Asia, and Australia.
Dry Climates • Geographers have determined two types of dry climates based on vegetation in each; desert and steppe. • Dry areas with sparse vegetation are called deserts. Rainfall seldom exceeds 10 inches/year and temperature vary widely from day to night. • Desert climates occur in just under 1/3 of the total land area, with the Sahara desert alone, covering almost the entire northern 1/3 of Africa.
Natural vegetation of deserts are designed to tolerate low humidity and wide temperature ranges. • In some desert areas underground springs produce an oasis, or an area of lush vegetation. • Boarding deserts are dry, treeless grasslands called steppes. • Rainfall averages 10-20 in/year. • Largest steppes found across eastern Europe and western and central Asia.
Mid-Latitude Climate • The world’s mid-latitudes include four temperature regions. • Along western coastlines between 30⁰ and 60⁰ North and South are regions with a marine west coast climate. These regions include the Pacific coast of the U.S., much of Europe, and parts of South America, Africa, Australia, and New Zealand.
Marine West Coast Climate • Ocean winds bring cool summers and damp winters and abundant rainfall, allowing for the growth of coniferous and deciduous trees. • Typical of marine west coast climates are mixed forests with both kinds of trees.
Mediterranean Climate • Lands surrounding the Mediterranean Sea mild, rainy winters and hot, sunny summers. • Vegetation includes chaparral. • Mediterranean climate is classified of every location with similar climates and vegetation, such as Southern California and parts of Southern Australia.
Humid Sub-Tropical • Short, mild winters and nearly year round rain. • Found in the southeastern United States, South America, and Asia. • Wind patterns and high pressure from nearby oceans keep humidity levels high. • Vegetation consists of prairies and deciduous forests.
Objectives: • Explain High Latitude climates • Identify Highland Climates • Evaluate Climatic Change
Humid Continental • Humid continental climates are not impacted by landforms. • The further north one travels, the longer and more severe the winters and shorter and cooler the summers. • Vegetation is similar to marine west coast areas, with evergreens outnumbering deciduous trees in the northernmost areas of the region.
High Latitude Climates • Freezing temperatures are common throughout much of the year due to lack of direct sunlight. • This results in little vegetation. • Just south of the Arctic Circle is the subarctic climate regions. Winters are bitterly cold, and summers are short and cool. • Temperatures vary from winter to summer as much as 120⁰F.
In the subarctic, only a thin layer of surface soil thaws each year. Below that is permafrost. • Closer to the polar regions are tundra regions, which have 6 months of darkness and light. • Trees cannot establish roots in the even thinner thawed soil. • Snow and ice, often more than 2 miles thick, cover the ground in the ice cap regions.
Highlands Climates • Elevation can determine a climate region, regardless of latitude. • High mountain regions, even near the equator, contain climates similar to high latitudes because of the thinning air temperature.
Climatic Change • During the last 1 to 2 million years, the earth has passed through four ice ages. • One hypothesis is that the earth absorbed less solar energy because of variations in the suns output of energy or rotation. • Another hypothesis is that dust from volcanic activity reflected sunlight back into space.
Human interactions with the environment often affect climate, such as burning fossil fuels which result in acid rain and smog. • Fewer forests, dams, and river diversions also affect the climate. • Dams and river diversions, intended to supply water to dry areas may cause new areas to flood or dry out.
Closure: • What did you learn today?
Homework • Page 69 1,3,4,5, and 6