BIOB 160 Week 4 Notes
BIOB 160 Week 4 Notes BIOB 160
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This 3 page Class Notes was uploaded by Alice Giem on Thursday September 22, 2016. The Class Notes belongs to BIOB 160 at University of Montana taught by Art Woods in Fall 2016. Since its upload, it has received 87 views. For similar materials see Principles of Living Systems in Biology at University of Montana.
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Date Created: 09/22/16
September 19, 2016 Kinds of Ecology Global ecology Landscape ecology Ecosystem ecology Community ecology Population ecology Organismal ecology North American terrestrial biomes Global locations of rain forests and deserts Summary of Macro Patters Best of rain forest along the equator Major deserts are at 30 degrees N and 30 degrees S Deserts are usually on west sides of continents Temperate and variable beyond 30 degrees N or S Very cold beyond 60 degrees N or S Why do we have these particular macro patterns of Earth? Answer from first principles… 1. The sun delvers differential amounts of energy onto different parts of the Earth. a. The earth is a giant heat engine heated by the sun. b. Intensity of sunlight varies across the Earth’s surface i. Toward the poles, the sun’s rays are spread over a larger area and take a longer path through the atmosphere. ii. Near the equator, the sun’s rays strike earth’s surface perpendicularly 2. Water has astonishing properties. a. We live on a liquid planet! b. Hydrogen bonding leads to structural organization. Liquid water is much more structured than other liquids c. Water is the only common substance on earth to exist in solid, liquid, and gas phases. d. Five emergent properties of hydrogen bonding of water i. Very strong internal cohesion ii. Strong surface tension iii. High heat capacity; high thermal mass iv. Solid is less dense than the liquid! v. Great solvent e. Importance of high specific heat of water almost impossible to overstate. i. Water can absorb or give off a given amount of heat but changes temperature much less than other material ii. MODERATING and STABILIZING influence iii. Since Earth’s surface is mostly water, this greatly moderates temperature fluctuations. iv. Since we are mainly water, we are also greatly buffered against external temperature fluctuations. 3. Differences in the temperatures of fluids (air and water) drive convective flows in those fluids a. Hot air is less dense than cool air so it rises i. Hadley Cells b. Cold, salty seawater is denser than warmer, fresher seawater c. Global patterns of ocean circulations: deserts mostly on the west sides of continents, with old ocean water nearby i. Cold water doesn’t evaporate so clouds don’t form and nothing rains 4. Rising air cools (PV=nRT; the ideal gas law) 5. Cool air does not hold as much water as hot air a. Water condenses out of air as it rises and cools i. Thermal updraft – air rising and cooling at 10 degrees C per 1000 meters 1. Dew Point- water turns from gas to liquid 2. Air continues of rise, but cooing rate offset by the heat of condensation, air only cools at 6 degrees C per 1000 meters b. Air masses that rise over mountains tend to lose a lot of their moisture. East sides of mountain ranges are “raid shadows” Patterns of rising and falling air in Hadley Cells account for preponderance of deserts at 30 N and 30 S latitude. September 21, 2016 Climate Change The starting point: the global mean surface temperature has increased since humans began directly observing it with thermometers. Causes Most scientists accept that the Earth has warmed up Is it due to greenhouse gases produced by humans building up in the atmosphere, or is it part of natural cycles of warming and cooling? The greenhouse effect is real. It keeps the Earth’s surface warmer than it would otherwise be. The physics of this effect are well known—and depend on how several trace gases in the atmosphere interact with heat. The carbon dioxide in the atmosphere is acting like a blanket and reflecting the heat back down at the Earth Some minor components of the atmosphere exert a disproportionate effect on how much heat the atmosphere retains. Greenhouse gas concentrations have jumped since the start of the industrial revolution Charles Keeling was the first to take detailed measurements. He set up his instruments on top of Mauna Loa, as far from industrial sources of carbon dioxide as possible This increase is not restricted to Mauna Loa. It turns out that the carbon dioxide concentration is going up everywhere. Historically, there has been a strong correlation between temperature and carbon dioxide. Most of the increase in atmospheric carbon dioxide concentration is due to the combustion of fossil fuels. Other consequences besides higher temperatures…. Rising Sea Levels o This Is occurring because Glaciers and ice fields are melting Higher sea temperatures is causing water to expand The higher the sea level the higher the chance of serious hurricanes and such Retreating glaciers Ocean acidification o Over the last 200 years, about half of all CO2 produced on earth has been absorbed by the oceans o But the carbon dioxide becomes an acid when it dissolves in water
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