Solar radiation and winds determine climate The sun’s rays are more direct at the equator and more spread out at the polar regions The tilt of the earth can cause one hemisphere to be warmer than the other
Air currents have a direct affect on rainfall.
Topography influences climate Topography – surface features of land Mountains affect climate Leeward side is in a rain shadow Bodies of Water influence the climate Ex: Ocean water gains & loses heat slower than land 39-4
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39.5 The tundra is cold & dark much of the year Arctic tundra encircles the Earth just south of the ice- covered polar seas in the Northern Hemisphere Because rainfall amounts to only about 20 cm a year, the tundra could possibly be considered a desert Only the topmost layer of soil thaws, permafrost beneath this layer is always frozen Trees are not found in the tundra 39-10
Figure 39.5 Tundra, the northern-most ecosystem 39-11
39.6 Coniferous forests are dominated by gymnosperms Taiga (called boreal or northern forest), exists south of the tundra and covers approximately 11% of the Earth’s landmasses Temperate rain forest – coniferous forest that runs along the west coasts of Canada and the United States 39-12
Figure 39.6 Taiga, a northern coniferous forest 39-13
39.7 Temperate deciduous forests have abundant life Temperate deciduous forests Climate in these areas is moderate, with relatively high rainfall Seasons are well defined Trees (oak, beech, sycamore, and maple) have broad leaves and are deciduous – lose their leaves in fall and grow them in spring 39-14
Figure 39.7 Temperate deciduous forest in the fall 39-15
39.8 Temperate grasslands have extreme seasons Temperate grasslands Very cold winters and hot and dry summers (Ex: praries) Small mammals, (mice, prairie dogs, and rabbits) live below ground, but usually feed aboveground Virtually all grasslands have been converted into agricultural lands because of their fertile soils 39-16
Figure 39.8 Temperate grassland in the summer 39-17
39.9 Savannas have wet-dry seasons Savannas – in regions where a cool dry season is followed by hot rainy season Largest savannas are in central and southern Africa African savanna supports the greatest variety and number of large herbivores of all the biomes 39-18
39.10 Deserts have very low annual rainfall Deserts usually found at latitudes of about 30° in both the Northern and Southern Hemispheres Most have plants highly adapted to survive long droughts, extreme heat, and extreme cold Some animals are adapted to the desert environment Exs: Camels and sidewinders 39-20
Figure 39.10 Desert with some vegetation 39-22
39.11 Tropical rain forests Tropical rain forests Diversity of species is enormous Complex structure, with many levels of life, including the forest floor, the understory, and the canopy 39-23
Classification of Lakes Lakes are often classified by nutrient status Oligotrophic lakes are nutrient-poor, having a small amount of organic matter and low productivity Eutrophic lakes are nutrient-rich, having plentiful organic matter and high productivity Eutrophication: “over fertilization” too much phosphorous = algae growth in lakes 39-28
39.13 Marine ecosystems include those of the coast and the ocean Coastal Ecosystems Border the Oceans Salt marshes, mudflats and mangrove swamps are ecosystems that occur at a delta Estuary – where fresh water & sea water mix as a river enters the ocean Ecologically important areas Large amount of nutrients support a wide variety of species 39-30
39.13 Marine ecosystems: The Ocean Oceans Phytoplankton (algae) is food for the entire ocean Coral reefs Areas of biological abundance just below the surface in shallow, warm, tropical waters Densely populated with life 39-32
Connecting the Concepts: Chapter 39 Topography influences climate There are several different land-based ecosystems on the earth, each with unique characteristics. There are several fresh-water ecosystems Coastal ecosystems include Estuaries Marine ecosystems cover most of the surface of the earth 39-34
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