NATS 101 Updates Add your name to Class ListServe! First QUIZ on Thursday Review session tomorrow at ~5PM –Location TBD. Will be announced via Listserve Textbooks Note-takers & takees meet after class PBS NOVA Mars: Dead or Alive tonight 8:00 1st anniversary of Katrina this week Quick update on Ernesto

4” by 6” Cards Today’s assignment Name, SID – legible penmanship What worked What didn’t and needs clarification

Practice Surface Station Sea Level Pressure Leading 10 or 9 is not plotted Examples: plotted as plotted as plotted as 360 Ahrens, p Decimal point What are Temp, Dew Point, SLP, Cloud Cover, Wind Speed and Direction?

Average and Record MAX and MIN Temperatures for Date

Climate of Tucson Probability of Last Freeze Cool Site: Western Region Climate CenterWestern Region Climate Center

Climate of Tucson Probability of Rain Cool Site: Western Region Climate CenterWestern Region Climate Center

Climate of Tucson Extreme Rainfall Cool Site: Western Region Climate CenterWestern Region Climate Center

Climate of Tucson Snow! Cool Site: Western Region Climate CenterWestern Region Climate Center

Summary Weather - atmospheric conditions at specific time and place Weather Maps  Instantaneous Values Climate - average weather and the range of extremes compiled over many years Statistical Quantities  Expected Values

NATS 101 Lecture 3 Temperature, Heat Transfer and begin Radiation

What is Temperature? Microscopic View Energy due to random jiggling of molecules Related to average molecular speed; 500 m/s (=1100 mph) at room temperature for air

Temperature and Density Consider volume of air If air is warmed: The molecules will move faster, have “stronger” collisions, and tend to become spaced farther apart Volume increases, so density decreases Warmer  less dense

Temperature Scales Fahrenheit ( o F) - relative US public standard Celsius ( o C) - relative Freezing point 0 o C Boiling point 100 o C o C= 5/9 ( o F-32) Kelvin (K) - absolute K= o C+273 Ahrens p27

What is Heat? Heat-Energy in the process of being transferred from a warmer object to a cooler object Consider a pot of water on a hot burner. Consider the following questions: Williams, p. 19

Heat Transfer Questions What causes the… Pan bottom and handle to get warmer? Top of the water to become warmer? Water temperature to not exceed 100 o C? Region away from side of pan to feel warm? Williams, p. 19

Conduction Heat transfer due to collision of molecules. Conduction warms the bottom of the pan! Conductivity - rate of heat transfer across a 1 cm thick slab of material if one side is kept 1 o C warmer than the other Cheap Experiment: Touch your chair! 1 cm Metal WaterAir Heat Transfer 1oC1oC 0oC0oC

Heat Conductivity

Specific Heat Capacity Heat required to raise temperature of 1 gm of substance 1 o C. Metal has lower heat capacity than water!

Convection Heat transfer due to vertical exchange of mass Occurs in fluids (liquids, gases) because of gravity Warm, buoyant air rises - Cool, dense air sinks Convection warms top of liquid! Warm Cool Warm Cool Warm Cool heat below - convectionheat side - convectionheat top - no convection gravity

Convection Movies 2D Convection Tank Animation2D Convection Tank Animation  2D Convection Model Ra=10**6 2D Convection Model Ra=10**7 IC1 2D Convection Model Ra=10**7 IC2 3D Rayleigh-Benard Convection Model3D Rayleigh-Benard Convection Model  Last hour movie of clouds and moist convection over Catalina mountains

Energy States and Water Phases water molecules are tightly packed in a crystal alignment that prevents them from changing shape LOW ENERGY STATE attractive forces btw molecules weaken and individual molecules can move around each other, but they can not break away SLIGHTLY HIGHER ENERGY STATE water molecules move very rapidly and are not bound together EXTEMELY HIGH ENERGY STATE Small Energy Change Large Energy Change

Latent Heat Ahrens, p 28 Weak attraction between molecules +540 cal/gm +80 cal/gm -540 cal/gm -80 cal/gm -620 cal/gm +620 cal/gm Strong attraction between molecules Some attraction More Ordered Phase Less Ordered Phase Surrounding air warms Surrounding air cools

Latent Heat Energy associated with phase of matter. Must be either added to or taken from a substance when it changes its phase. –To turn liquid water into solid ice, must remove energy from the liquid water. –To turn liquid water into vapor, must add a lot of energy to the liquid water.

Heat Transfer Questions What causes the… Pan bottom and handle to get warmer? Top of the water to become warmer? Water temperature to not exceed 100 o C? Region away from side of pan to feel warm? Williams, p. 19

Modes of Heat Transfer Williams, p. 19 Latent Heat

Take Home Concepts Heat-Energy transfer due to temperature differences Three modes of heat transfer Conduction – molecule to molecule Convection – transport of fluid Radiation – electromagnetic waves Latent Heat – energy of phase changes

Modes of Heat Transfer Energy is only converted from one form to another or transferred from one place to another. Energy is transferred from hot to cold. Conduction - Molecules colliding; most efficient at interface. Convection - Requires movement of a fluid or gas.

Radiation Any object that has a temperature greater than 0 K, emits radiation. This radiation is in the form of electromagnetic waves, produced by the acceleration of electric charges. These waves don’t need matter in order to propagate; they move at the “speed of light” (3x10 5 km/sec) in a vacuum.

Electromagnetic Waves Two important aspects of waves are: –What kind: Wavelength or distance between peaks. –How much: Amplitude or distance between peaks and valleys. Wavelength AmplitudeFrequency

Why Electromagnetic Waves? Radiation has an Electric Field Component and a Magnetic Field Component –Electric Field is Perpendicular to Magnetic Field

Photons NOT TO CONFUSE YOU, but… Can also think of radiation as individual packets of energy or PHOTONS. In simplistic terms, radiation with –shorter wavelengths corresponds to photons with more energy and –higher wave amplitude to more BB’s per second

Electromagnetic Spectrum WAVELENGTH Danielson, Fig Wavelengths of Meteorology Significance

Emitted Spectrum White Light from Flash Light PurpleGreen Red Emitted radiation has many wavelengths. Prism (Danielson, Fig. 3.14)

Emitted Spectrum Energy from Sun is spread unevenly over all wavelengths. Wavelength Energy Emitted Emission spectrum of Sun Ahrens, Fig. 2.7

Wien’s Law The hotter the object, the shorter the brightest wavelength. Danielson, Fig. 3.19

Wien’s Law Relates the wavelength of maximum emission to the temperature of mass MAX = (0.29  10 4  m K)  T -1 Warmer Objects => Shorter Wavelengths Sun-visible light MAX = (0.29  10 4  m K)  (5800 K) -1  0.5  m Earth-infrared radiation MAX = (0.29  10 4  m K)  (290 K) -1  10  m

Wien’s Law What is the radiative temperature of an incandescent bulb whose wavelength of maximum emission is near 1.0  m ? Apply Wien’s Law: MAX = (0.29  10 4  m K)  T -1 Temperature of glowing tungsten filament T= (0.29  10 4  m K)  ( MAX ) -1 T= (0.29  10 4  m K)  (1.0  m) -1  2900K

Stefan-Boltzmann’s (SB) Law The hotter the object, the more radiation emitted. When the temperature is doubled, the emitted energy increases by a factor of 16! Stefan-Boltzmann’s Law E= (5.67  Wm -2 K -4 )  T 4 E=2  2  2  2=16 4 times Sun Temp: 6000K Earth Temp: 300K Aguado, Fig. 2-7

How Much More Energy is Emitted by the Sun per m 2 Than the Earth? Apply Stefan-Boltzman Law The Sun Emits 160,000 Times More Energy per m 2 than the Earth, Plus Its Area is Mucho Bigger (by a factor of 10,000)!

Radiative Equilibrium Radiation absorbed by an object increases the energy of the object. –Increased energy causes temperature to increase (warming). Radiation emitted by an object decreases the energy of the object. –Decreased energy causes temperature to decrease (cooling).

Radiative Equilibrium (cont.) When the energy absorbed equals energy emitted, this is called Radiative Equilibrium. The corresponding temperature is the Radiative Equilibrium Temperature.

Key Points Radiation is emitted from all objects that have temperatures warmer than absolute zero (0 K). Wien’s Law: wavelength of maximum emission MAX = (0.29  10 4  m K)  T -1 Stefan-Boltzmann Law: total energy emission E= (5.67  W/m 2 )  T 4

Key Points Radiative equilibrium and temperature Energy In = Energy Out (Eq. Temp.) Three modes of heat transfer due to temperature differences. Conduction: molecule-to-molecule Convection: fluid motion Radiation: electromagnetic waves

Reading Assignment Ahrens Pages Problems 2.7, 2.9, 2.10, 2.11, 2.12