F 311 1st Edition Exam 1 Study Guide Week 2 How objects gain loose heat Conduction convection radiation and waterevaporation condensation Conduction Transfer of energy through matter Transfer and distribution of neat energy from atom to atom within a substance Convection Transfer of heat energy in a gas liquid or solid by movement of currents Radiation Electromagnetic waves directly transporting energy through space Everything in the universe is either losing or gaining energy through radiation Temperature and electromagnetic radiation Temperature is created by the collision ofmolecules Under higher pressure molecules collide morefrequently generating more heat and with greater energy molecules move faster colliding more frequently All objects shine emit radiation Measuring Energy The unit of energy flow per unit of area W m2 a Watt W is a J s a rate of flow where a Joule J is an energy unit an amount of energy 1 Newton of force over a m distance Radiation wavelength energy and temperature Energy is measured as W m2 Different types of electromagnetic radiation have different wavelengths Radiation with longer wavelengths has lower energy meaning it shines less and has lower temperatures The wavelengths of visible light range from 400 nm violet to 700 nm red Hotter objects shine brighter emit more energy persecond and shine at shorter wavelengths Greenhouse effect Greenhouse effect results from gases absorbing longwave radiation warming up and then emitting the radiation to space Shortwave radiation not reflected by the atmosphere passes through and heats the earth s surface causing the surface to shine longwave radiation Gases water CO2 CH4 N2O absorb longwave radiation that would be leaving back to space which causes the gases to warm up like a blanket The gases keep warming up emitting longwave radiation that warms the atmosphere and surface of the earth i e the greenhouse effect The atmosphere can t hold onto infinite amounts of heat as it warms it emits more energy until we have a balance of Incoming radiation Outgoing radiation The greenhouse effect in a nutshell Earth is about 30oC warmer with its greenhouse effect than it would be without it 2 3rds of our warmth depend on this Some greenhouse is good but to much is bad Solar input variation Sun doesn t warm Earth evenly because of the curvature of the earth Sunlight that strikes at an angle is spread across a greater surface area and is a less intense heat source than a beam impinging directly Light coming onto a slope is proportional to the sin of the angle between the slope and the sun Light Sunlight sin h Earth s tilt of 23 5o and revolution around the sun creates seasonal heating patterns At solstice tilt keeps one polar region with 24 hours of light and the other with 24 hours of darkness At equinox tilt provides exactly 12 hours of night and 12 hours of day everywhere At one location the influence of slope angle and aspect make little difference in summer but huge difference other times Adiabatic cooling or heating Adiabatic lapse rate About 3 C 1000ft 9 8 C 1000 m for dry air About 1 5 C 1000 5 C 1000 m for saturated air Lower lapse rate for saturated because air is warmed as water vapor condenses and releases heat Taking a fixed mass of air and raising or lowering its pressure and volume compress and it heats Energy budgets Incoming and outgoing energy must balance on average ut there are huge differences from place to place Way more solar heating in tropics Some places deserts emit much more than others high cold clouds over rainforests Incoming solar minus outgoing longwave Must be balanced by horizontal transport of energy by atmosphere and oceans Clearcutting clearcutting increases day time temps and lowers night time temps montana example Week 3 Patterns of Water Inputs and Outputs across Space and Time Probabilities A once in a century event really means a 1 chance of the event in any year 1 probability for an event this year 99 probability of no event Probability of a 5 year span with no event 0 99 x 0 99 x 0 99 x 0 99 x 0 99 0 951 95 Probability of a 100 yr span with no event 0 99 100 0 366 37 chance of no event Cool rule Whatever the return interval of an event there s a 37 chance of no event within that interval Climate of Rockies Summer warm moist air moves from the gulf bringing in air masses Fall winter spring pacific front storms origninating from Alaska are stripped of air moisture from sierra nevadas and rockies Airtic air masses engulf the middle of the continent Forest Water Balance and the Role of Trees Water flows in forests 1 Precipitation 2 Interception infilatration overland flow 3 Uptake 4 Transpiration evaporation Watershed streamflow yield or dishcharge precipitation interception loss evaporation loss transpiration loss Weir More streamflow raises level of water in pond measuring water level can lead to calculating streamflow Changes in watershed flows fluxes after cutting trees Fraser experimental forest Cutting 40 of the watershed increased streamflow from 30 to 38 cm yr More snow accumulates in the cut strips because leaves do not intercept it Intercepted snow evaporates Cutting trees usually increases water flow in streams effect increases with precipitation Hydrologic response follows Canopy response How much water is used by trees interception transpiration Transpiration results from potential differences from the water to the air through the tree moderated by the leaf pores or stomata Potential Things go from higher potential to lower potential Things go downhill How Transpiration Works At night temperature is cooler and relative humidity is higher Air has no suction when Stomata are closed Water potential Energy per mol in pressure units relative to pure water Vapor pressure deficit is A The amount of water the air could hold minus B The amount of water currently in the air In soils water moves downhill It can also be sucked into tiny poor spaces because it sticks to surfaces like in a test tube Water movement up trees 1 The air is drier than the leaf 2 The leaf is drier than the twig 3 The twig is drier than the stem 4 The stem is drier than the root 5 The root is drier than the soil Patterns of Tree Growth and Water Drought Growth rates of trees vary among years giving different ring widths for this ponderosa pine Across geographic rainfall gradients productivity often increases with precipitation At a single site wet years have higher growth than drier years Within a site