In the News: http://www.nytimes.com/2009/09/04/science/earth/04arctic.html?hp
In the News: Reversal in Arctic cooling trend Kaufman et al. 2009, Science http://www.nytimes.com/2009/09/0 4/science/earth/04arctic.html?hp
In the News: http://www.npr.org/templates/player/mediaplayer.html?action=1&t=1&islist=false&id=112496096&m=112502238 http://www.npr.org/templates/story/story.php?storyid=112496096
QUIZ #1: Answers (1) Why is the ozone layer important? It blocks harmful shortwave radiation yet allows long-wave radiation to reach the earth s surface which supports biological processes (photosynthesis etc.) (2) What is the difference between water vapor and visible clouds? Water vapor is a gas and visible clouds are made up of liquid molecules (condensed water vapor). 4
QUIZ #1: Answers (3a) 1. (Right plot) what is the atmospheric pressure associated with the High in MT? 1023 2. Where is there a low pressure trough? NE MT, S. Idaho, & Central Utah 5
QUIZ #1: Answers (3b) (Left plot) what is the wind direction and approx. speed? NW @ ~ 5 knots 1. (left plot) what is the atmospheric pressure? 1018.5 (<500 so 10185/10 = 1018.5) 2. (left plot) what is the atmospheric pressure trend? Decreasing then stable 3. (left plot) what is the sky cover? clear 6
QUIZ #1: Answers (3b) 1. (left plot) what is the atmospheric pressure? 1018.5 If reported value greater than 500: Initial 9 is missing. Place it on left, then divide by 10. For example: 827 becomes 9827 / 10 = 982.7 mb If reported value less than 500: Initial 10 is missing. Place it on left, then divide by 10. For example : 185 becomes 10185 / 10 = 1018.5 mb. 7
Weather Journal Example: 1. Example: 2. Grading Rubric: 8
Solar Radiation and the Seasons (ERTH 303 8 September, 2009) 1. Solar Radiation: a. Energy types energy transfer b. Radiation quality quantity c. Solar constant NASA: http://apod.nasa.gov/apod/image/9909/equinoxprom_eit_big.jpg
Energy (review) Energy = ability to do work units = joule [J] Power = rate of energy release unit = watt [W] = J / sec
Energy types Potential energy: energy that has not been used yet, or energy stored within a physical system allposters.com
Energy types Kinetic energy: energy in use, or the energy of motion Lindsey Kildow, from the New York Times:http://www.nytimes.com/2007/01/29/sports/29ski.html
Energy energy transfer mechanisms Conduction: heat transfer by its movement through a substance (littl substance (little movement of molecules) Convection: heat transfer by movement of a fluid (a liquid or gas) wind HOT oil (50 C) HEAT Trans-Alaska Pipeline in the Alaska Range
Energy energy transfer mechanisms Conduction: heat transfer by its movement through a substance Convection: heat transfer by movement of a fluid * very important for weather phenomena Pyrocumulus cloud in interior Alaska, Erickson Creek Fire, 2003.
Energy energy transfer mechanisms (Electromagnetic) Radiation: no medium required for transmission differ by wave properties a) Quantity (or Intensity) is a function of amplitude b) quality or type is a function of wavelength (e.g., gamma vs. infrared) magnetic electric Aguado and Burt Fig. 2-5
Radiation (Electromagnetic) Radiation: Aguado and Burt Fig. 2-6 wave length (μm = 0.000001 m)
Radiation Who knew? all objects emit radiation, over a range of wavelengths (i.e. of all different types- humans ~ 9 light bulbs) If an object were to emit the maximum amount of radiation possible at all wavelengths, it would be a black body
Radiation Black body radiation (e.g. perfect radiation) is described by Stefan-Boltzmann Law: energy radiated per unit area per unit time is proportional to the forth power of the black body s temperature Or, in math: I = σt 4 I = intensity (W m -2 ) σ = Stefan-Boltzmann constant (5.67x10-8 W m -2 K -4 ) T = temperature ( K)
o f R a d i a Radiation t i o n Implications of Stefan-Boltzmann Law: hotter bodies emit more intense energy
Radiation Implications of Stefan-Boltzmann Law: hotter bodies emit more intense energy Sun 174,000 times more intense ative intensity rela wave length (μm)
Radiation Graybodies = imperfect radiator (some energy absorbed) most liquids and solids Earth and sun ~ black bodies Atmospheric liquids & gases = gray bodies Stefan-Boltzmann Law gets modified: I = εσt 4 ε = emissivity = proportion of energy emitted from an object, relative to a black body (ranges between 0-1)
Radiation Graybodies = imperfect radiator (some energy absorbed) most liquids id and solids Stefan-Boltzmann Law gets modified: d I = εσt 4 Application of the Stefan-Boltzmann Law to the atmosphere is not appropriate emissivity in atmosphere influenced by many other factors (e.g. water vapor)
Radiation Wien s Law: relates the modal wavelength emitted from an object to temperature Or, in math: λ max = 2900/T λ max = modal wavelength (μ) max T = temperature ( K)
o f R a d i a Radiation t i o n Implications of Wien s Law: hotter bodies emit more intense energy
Radiation SO WHAT? Useful consequences of S-B and Wien s Law: Colorenhanced infrared satellite imagery: enhanced infrared satellite imagery: http://www.ssd.noaa.gov/ps/pcpn/data/rt/na-ir4-loop.html
Solar Constant Sun emits 3.865 x 10 26 W energy does not change from Sun to Earth... but it s intensity does.
Solar Constant inverse square law Inverse square law: energy intensity diminishes in proportion to the distance squared Solar constant = 3.865x10 26 W / 4π(1.5x10 11 m) 2 = 1367 W/m 2
Solar Constant
Causes of Earth s Seasons 1. The Seasons: a. Earth Sun geometry 2. Energy Balance and Temperature a. Atmospheric influences on insolation: absorption, reflection, and scattering 29
Seasons: Earth-Sun geometry Why does Earth have seasons? Changes in the quantity of incoming solar radiation, or insolation, at a given location. http://geography.uoregon.edu/envchange/clim_animations/gifs/nswrs_web.gif 30
Seasons: Earth-Sun geometry Why does insolation vary? 1. Earth s revolution around the sun: * 3% change in distance to sun between perihelion (winter today) and aphelion (summer today) 7% change in insolation 31
Preview mechanisms of climate change The path of Earth s revolution changes through time, and thus the date of perihelion and aphelion change (21,000 yr to cycle through the calendar) and the difference in insolation can vary up to 23%. the length of the season also changes: http://aa.usno.navy.mil/data/docs/earthseasons.php 32
Seasons: Earth-Sun geometry Why does insolation vary? 2. Earth s axial tilt = 23.5 5 relative to elliptical plane rotation axis http://upload.wikimedia.org/wikipedia/commons/6/61/axialtiltobliquity.png 33 Early Winters Spire and Blue Peak, North Cascades, WA
Seasons: Earth-Sun geometry Solstice: What is the one Earth-Sun relationship defining a solstice? 34
Seasons: Earth-Sun geometry Solstice: Maximum axial tilt in relation to the Sun Hemispheric p axes inclined toward or away from Sun Causes maximum difference in solar insolation, between hemispheres 35
Seasons: Earth-Sun geometry June Solstice (~ June 21) * Subsolar point = Tropic of Cancer (23.5 o N) * 24 h daylight at Arctic Circle = 90-23.5 = 66.5 N December Solstice (~ Dec. 21) * point = Tropic of Capricorn (23.5 o S) 24 h daylight at Antarctic Circle = 90-23.5 = 66.5 S 36