UNT BIOL 2140 - Exam 3 Study Guide (13 pages)

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Exam 3 Study Guide

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Exam 3 Study Guide


climate and biomes, climate change and remote sensing

Study Guide
University of North Texas
Biol 2140 - Ecology
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BIOL 2140 Exam 3 Study Guide Lectures 1 12 Lecture 1 October 27 Global climate patterns moisture and temperature are key factors that reflect biological communities Insolation patterns amount intensity of sunlight received in one area vs another Insolation is responsible for determining moisture and temperature in a given area Solar energy irradiation sunlight heat Sun provides a lot of energy 25 reflected by clouds and gases reflectivity albedo 25 absorbed in the atmosphere into greenhouse gases 50 reaches earth What happens if we didn t have the greenhouse effect the earth would be very cold Differential insolation drives weather and climate What is the difference between weather and climate Weather atmospheric conditions at the moment Climate long term characteristic weather patterns averages Regions of intensity in a globe model High intensity solar energy hits concentrated on a small area equator region of greatest warming Lower intensity the same amount of solar energy hits spread over a broader area due to shallow angle of impact less warming poles Equatorial conditions 1 Solar energy hits the air and water causing the air and water molecules to move faster higher kinetic energy 2 As the water molecules increase in kinetic energy more of them gain the escape velocity to break their hydrogen bonds and evaporate into the air as vapor the various other gases in the air are similarly imparted with energy such that they too move faster causing them to be more spread out the air mass is less dense and begins to rise 3 As the air and water gases rise upward through the atmosphere there is less and less weight of atmospheric gases pushing on them from above the volume of the air mass expands just because it isn t being squeezed as much anymore the molecules are able to move even further apart but simply due to the release of pressure rather than a gain of kinetic energy 4 All else being equal this expansion in volume due only to reduction in pressure causes the temperature of the air mass to fall simply because the molecules aren t colliding with each other as frequently anymore This is called adiabatic cooling and it explains why the air that is released out of a car tire is cool The opposite effect where an increase in pressure squeezing causes the gas body to warm is called adiabatic heating 5 What happens to water molecules when they cool They form hydrogen bonds condense into water droplets Global summary Land masses disrupt temperature distribution Ocean is hottest along the equator and cooler towards the poles Equator warm air and water rise low pressure system air cools and drops rain Heat water vapor other greenhouse gases transported poleward Poles Dry air kinetically cools and sinks high pressure system little rain if warming patterns existed without rotation convection currents Uneven insolation pattern is responsible for the earth s very broad climate patterns A warm humid rainy equatorial region vs cold dry polar regions Heat is absorbed by water and other atmospheric gases which rise at the equator and carry the heat with them to the poles If not for this redistribution of heat the earth s temperature gradient would be even stronger even hotter at the equator and even colder at the poles Lecture 2 October 29 Insolation and wind The sun creates air movement aka wind Air is warmed the most at the equator causing it to rise As the air lifts upwards it cools adiabatically due to the reduction in atmospheric pressure around it and drops rain High in the atmosphere the air diverges to the north and south where else can it go carrying heat with it toward the poles The air currents collide and descend at the poles again where else can the air go As the air descends it warms adiabatically due to the increasing atmospheric pressure around it Once it hits ground level the air is forced to spread back across the surface of the earth to the equator The Coriolis Effect As the air is doing all this moving around driven by solar energy the earth s rotation causes it to be deflected or to appear to be deflected into a curve The Coriolis Effect is due to the shape and rotation of the earth combined with the laws of inertia The deflection is to the right in the northern hemisphere and to the left in the southern Earth rotates toward the east Objects sitting near the poles have lower inherent eastward velocity momentum compared to objects sitting near the equator As these objects move toward the equator they are increasingly slow relative to the surroundings and thus appear to drift west when really the surface of the earth is just drifting faster east North south motion simple velocity differences in momentum Objects moving toward the equator away from a pole effectively move slower and slower east as they go Objects moving away from the equator toward a pole effectively move faster and faster east as they go relative to the surface of the earth East west motion conservation of angular momentum Eastbound objects move relatively faster than the surface of the earth fling away from earth s core drift toward the equator Westbound objects move relatively slower than the surface of the earth fall toward earth s center drift toward the pole warmer air water vapor cooler air water droplets condensation Earth s rotation breaks up air movement to explain why we tend to have forests vs deserts where we do by latitude Earths tilt creates seasons The region of most intense solar heating evaporation intertropical convergence shifts north and south of the equator seasons We call the region of the earth that receives the maximum solar intensity for at least a part of the year the tropics between 23 5 N and 23 5 S Ocean currents influence climate The Gulf Stream is responsible for keeping Europe warm for its latitude Water warms as it moves west along the equator The Coriolis force turns it to the right as it also slams against the east coast of North America This causes a jet of water to shoot up the coast like squeezing a bar of soap from your hand a boundary current known as the Gulf Stream The warm Gulf Stream water moves north so rapidly that it still retains most of its heat when it reaches the Arctic There it finally slows and cools releasing its heat into the air to blow across Europe keeping Europe far warmer than the same latitudes in Canada Land complicates climate Land mass positioning influence ocean circulation changes distribution of heat Land absorbs holds and reflects heat

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