Charles Hakes Fort Lewis College1

Charles Hakes Fort Lewis College2 Atmospheres/ Greenhouse Effect/ Spectroscopy

Charles Hakes Fort Lewis College3 Logistics Midterm grades will be posted by Monday (faculty.fortlewis.edu/hakes_c)faculty.fortlewis.edu/hakes_c Review Atmospheres Planet Temperatures Spectroscopy Green House Effect

Charles Hakes Fort Lewis College4 Lab Notes Binocular lab? Outside “extra” lab(s) due this week! - make sure you get your 40 points.

Charles Hakes Fort Lewis College5 Distance to Mercury Look up distance from Sun (A.U.) in appendix… Need eccentricity of Mercury.

Charles Hakes Fort Lewis College6 Notes Lab credit is available if you join! link is on my home page download the software install and run - you will have to “connect” to the SETI project after you install after completing a work unit, join the FLC group me for credit (Keep running it if you want to keep the lab credit.)

Charles Hakes Fort Lewis College7 Review What was the most important thing you learned? Albedo is how much light gets reflected. Earth has an albedo of 0.3 Albedo is not related to libido. For any given temperature, the lighter stuff moves faster. Wein’s law:

Charles Hakes Fort Lewis College8 Blackbody Radiation (Review!) Higher temperature bodies radiate energy in shorter wavelength radiation. The Sun radiates at visible wavelengths The Earth (and other planets) radiate at much longer wavelengths.

Charles Hakes Fort Lewis College9 Figure 2.10 Blackbody Curves Note the logarithmic temperature scale. For linear scale, go look at the “black body” section of: do.edu/ do.edu/

Charles Hakes Fort Lewis College10 Wein ’ s Law The “peak” frequency of the radiation “curve” is directly proportional to the temperature of the radiator.

Charles Hakes Fort Lewis College11 You observe E-M radiation emitted from a warm dense object. The most radiation appears to be emitted at 5.8x10 -4 cm. What temperature is the object? A) 400 K B) 500 K C) 600 K D) 700 K

Charles Hakes Fort Lewis College12 You observe E-M radiation emitted from a warm dense object. The most radiation appears to be emitted at 5.8x10 -4 cm. What temperature is the object? A) 400 K B) 500 K C) 600 K D) 700 K

Charles Hakes Fort Lewis College13 Planet Temperature Go to Solar System Collaboratory on EVM “physics” page.Solar System Collaboratory A planet must balance absorbed light and radiated light to get a temperature. Light intensity decreases with distance. (another 1 /r 2 law) Farther from the sun, the absorbed light is less.

Charles Hakes Fort Lewis College14 Planet Temperature Go to Solar System Collaboratory on EVM “physics” page.Solar System Collaboratory A planet must balance absorbed light and radiated light to get a temperature. Light intensity decreases with distance. (another 1 /r 2 law) Farther from the sun, the absorbed light is less. Go to Solar System Collaboratory on planet temperature page.Solar System Collaboratory

Charles Hakes Fort Lewis College15 Figure 5.7 About 30% of the sunlight hitting the Earth is reflected

Charles Hakes Fort Lewis College16 To Atmosphere or Not Once you know a planet’s temperature you can see if it will have an atmosphere, and how that atmosphere can affect a planet’s temperature. Compare kinetic energy of molecules with “escape velocity” from the planet. Light molecules (of a given temperature T) move faster than heavy molecules of the same temperature. A small fraction will always escape.

Charles Hakes Fort Lewis College17 To Atmosphere or Not Primary atmosphere What a planet had after formation Mostly H, He - almost all gone from the terrestrial planets (never really was here) Secondary atmosphere Heavier molecules N 2, CO 2 From rock outgassing H 2 O from outgassing and comet impacts. O 2 from Life

Charles Hakes Fort Lewis College18 Earth’s Atmosphere 78% nitrogen 21% oxygen - this is from living organisms Plus Ar, CO 2, H 2 O. Note layers

Charles Hakes Fort Lewis College19 Figure 5.5 Earth ’ s Atmosphere

Charles Hakes Fort Lewis College20 Meteorology Science dealing with phenomena in the atmosphere (Not the study of meteors) Warm air rises and expands Cold air sinks and shrinks Must conserve linear and angular momentum.

Charles Hakes Fort Lewis College21 Figure 5.6 Convection

Charles Hakes Fort Lewis College22 Which will have the greatest effect on a planet’s temperature? A) doubling a planet’s distance to the sun B) doubling a planet’s albedo C) doubling a planet’s mass D) doubling a planet’s rotation rate

Charles Hakes Fort Lewis College23 Which will have the greatest effect on a planet’s temperature? A) doubling a planet’s distance to the sun B) doubling a planet’s albedo C) doubling a planet’s mass D) doubling a planet’s rotation rate

Charles Hakes Fort Lewis College24 Compared to Earth, the Moon undergoes temperature extremes because? A) It orbits the Earth, and therefore gets both closer and farther from the Sun than Earth B) It has no atmosphere C) It rotates very slowly D) Both B and C

Charles Hakes Fort Lewis College25 Compared to Earth, the Moon undergoes temperature extremes because? A) It orbits the Earth, and therefore gets both closer and farther from the Sun than Earth B) It has no atmosphere C) It rotates very slowly D) Both B and C

Charles Hakes Fort Lewis College26 Planet Temperatures Go to Solar System Collaboratory to see planet temperatures page.Solar System Collaboratory Look at fact sheet Earth - (albedo 0.3) 288 K Moon - (albedo 0.07) 280 K Mars - (albedo 0.2) 218 K Venus - (albedo 0.8) 730 K Compare model to fact sheet. Review model - distance and albedo.

Charles Hakes Fort Lewis College27 Planet Temperatures Compare the model to the fact sheet. Earth - (albedo 0.3) 288 K (model 255 K) Moon - (albedo 0.07) 280 K (model 273 K) Mars - (albedo 0.2) 218 K (model 214 K) Venus - (albedo 0.8) 730 K (model 219 K) Model with fast-rotating planet with variable albedo predicted temperatures that were too low. Something is missing from the model…

Charles Hakes Fort Lewis College28 What is Missing from the model? A) Realistic rotation rates for the planets B) Geothermal Energy C) Distance from the Sun D) Something else important

Charles Hakes Fort Lewis College29 What is Missing from the model? A) Realistic rotation rates for the planets B) Geothermal Energy C) Distance from the Sun D) Something else important

Charles Hakes Fort Lewis College30 Greenhouse Effect Exhale

Charles Hakes Fort Lewis College31 Removing all greenhouse gasses from the Earth’s atmosphere would be good A) True B) False

Charles Hakes Fort Lewis College32 Greenhouse Effect Visible light comes in though the atmosphere and heats the ground. Re-radiating infrared light can’t get out because the atmosphere is partially opaque. Greenhouse gasses must have at least 3 atoms in each molecule to absorb effectively in the IR. Note - “real” greenhouses merely stop convection from carrying away heat.

Charles Hakes Fort Lewis College33 Figure 2.8 Electromagnetic Spectrum

Charles Hakes Fort Lewis College34 Figure 5.7 About 30% of the sunlight hitting the Earth is reflected

Charles Hakes Fort Lewis College35 Greenhouse “Strength” Contributors Total atmospheric pressure Greenhouse gas percent Greenhouse gas effectiveness

Charles Hakes Fort Lewis College36 Add Greenhouse “Strength” to Model Earth Mars Venus

Charles Hakes Fort Lewis College37 Planet Temperatures Compare the model to the fact sheet. Earth - (A 0.3, GH 0.65) 288 K (model 289 K) Moon - (albedo 0.07) 280 K (model 274 K) Mars - (albedo 0.2) 218 K (model 218 K) Venus - (albedo 0.8) 730 K (model 730 K)

Charles Hakes Fort Lewis College38 Planet Temperatures Compare the model to the fact sheet. Earth - (A 0.3, GH 0.65) 288 K (model 289 K) Moon - (albedo 0.07) 280 K (model 274 K) Mars - (albedo 0.2) 218 K (model 218 K) Venus - (albedo 0.8) 730 K (model 730 K) Much better agreement!

Charles Hakes Fort Lewis College39 Greenhouse Runaway On Venus, the temperature was just high enough to keep most of the water in the atmosphere. CO 2 could not be absorbed into the water, and eventually trapped in the surface rocks. If all Earth’s CO 2 were released into the atmosphere, it would be ~98% CO 2, 2% N 2 and the pressure would be ~70x current.

Charles Hakes Fort Lewis College40 Figure 6.8 Venus, Up Close

Charles Hakes Fort Lewis College41 Figure 6.30 Venus ’ s Atmosphere

Charles Hakes Fort Lewis College42 Discovery 5-2a The Greenhouse Effect and Global Warming

Charles Hakes Fort Lewis College43 Discovery 5-2b The Greenhouse Effect and Global Warming

Charles Hakes Fort Lewis College44 What gas is the most significant contributor to Earth’s greenhouse effect? A) Methane B) Water vapor C) Carbon monoxide D) Carbon dioxide

Charles Hakes Fort Lewis College45 What gas is the most significant contributor to Earth’s greenhouse effect? A) Methane B) Water vapor C) Carbon monoxide D) Carbon dioxide

Charles Hakes Fort Lewis College46 Three Minute Paper Write 1-3 sentences. What was the most important thing you learned today? What questions do you still have about today’s topics?