Powerpoints Flashcards
Geostationary Satellites (GOES)
Stationary with respect to a fixed point on Earth’s surface (revolves at the same rate as Earth)
Farm from earth (~36,000 km away) => coarse spatial resolution, but good temporal sampling
Polar Orbiting Satellites
Orbit the earth from pole to pole
Closer to the Earth (~900km) => better spatial resolution, poorer temporal sampling
Study Surface Station Model Diagram
in powerpoints 1
90% of earth’s atmosphere (by mass) is below ________
16km (10 miles)
Weather
Specific state of the atmosphere at a given time/place
Climate
Accumulation or average of weather conditions over a long period of time
What is the atmosphere?
A fluid
A thin layer surrounding the Earth
Mainly a mixture of invisible gas with some solid and liquid particles, that stays in place due to the force of gravity
Major permanent gases of the atmosphere
Nitrogen N2 - 78%
Oxygen - O2 - 20%
Argon - Ar - 0.9%
Source of Nitrogen
Bacterial dentrification during decay of biological matter
Sink of Nitrogen
N-fixation by lightning, fires, or bacteria
Sources of Oxygen
Photosynthesis
Photolysis
Sink of Oxygen
Oxidation
Decomposition
Respiration
Hydrogen/Helium:
Earth’s first ATM ( probably)
light => easily escape Earth’s gravity
Water in the Atmosphere
Greenhouse gas
Variable concentration
Invisible
Carbon Dioxide
Greenhouse gases: “Trap” energy in lower atmosphere
Anthropogenic: caused by human activity
CO2 increases with plant decay during winter
CO2 decreases with plant growth during summer
Aerosols
Particles suspended in the air (dust, soot, salt)
Provide “nucleus” for cloud droplet formation (cloud condensation, nuclei, or CCN)
Can shade surface
Earth’s early atmosphere:
H2, He
Volcanic outgassing and the origins of our oceans:
CO2, H2O, and some N2
Life and the origin of our present atmosphere:
Drawdown of CO2, increase in O2
How old is the Universe:
~10 - 20 Ga (billions of years) 13 in specific
How do we know? - expansion, and the hubble constant
Earth’s First ATM
Earth forms via acretion (stuff clumps together)
Whatever happened to be hanging around at the time (H2)
Atmosphere rapidly lost to space; ripped off planet by bombardment
Earth’s second ATM
Volcanism and Heavy Bombardment (4.5-3.8 ga)
Earth’s third ATM
3.8 - 3.5 ga
LIFE!
Cyanobacteria
Photosynthesis
Red Beds
Form in more oxygen-rich environments (1-2% ATM)
Start around 2 Ga
Banded Iron Formations
Form in oxygen-depleted water environments (1-2%)
Stop around 2 Ga
Ultraviolet radiation does not permit =>
life on land, or in surface locations
O3 (ozone) layer is needed
As oxygen increases =>
Ozone increases via photochemical reactions
=> Ozone layer
What next?
Early life: anaerobic bacteria (photosynthesis)
Aerobic bacteria develop ~2 Ga (respiration)
Eukaryotic cells develop ~1.5 Ga
~0.5-0.1 Ga meiosis (sexual reproduction)
~600Ma - Present =>
Life takes off
Vertical sounding
Measurement of how temperature changes with height in the atmosphere
Water balloons lift “radiosondes” into the air
Graph with two bars
Right bar on graph is Temperature
Left bar on graph is Dewpoint Temperature
Lapse Rate
Rate at which temeprature decreases with height (positive when temperature gets colder with height)
Typically ~6.5C in the troposphere
Temperature Inversion
Vertical layer of the atmosphere where temperature increases with height
Lowest pressure ever recorded in the Atlantic
882 Mb
Density =
Mass / Volume
Pressure =
Force / Area
Force =
Mass * Acceleration
Weight =
Mass * Gravitational Acceleration
Pressure:
supports weight of air above a given location
Order of Atmosphere
Thermosphere
Mesopause
Mesosphere
Stratopause
Stratosphere
Tropopause
Troposphere
Troposphere
Tropo (turning) sphere - where weather happens
- heated from below
Lapse rate = ~6.5 C/km
Tropopause: where temperature stops decreasing (isothermal layer)
~16 km in the tropics
~6km in polar regions
Stratosphere
Stratum (layer) sphere - no weather
Temperature increases with height (inversion)
- heated from above by ozone
Stratopause: where temperature stops increasing
=> ~50 km in the tropics
Weight of water per cm^2
10g/cm^2
Air pressure:
1013 g/cm^2
Energy
The ability to do work
units: Joules, or calories
Potential energy
Potential to do work
Kinetic energy
Energy of motion
Internal (thermal) energy
Energy of molecular motion in a substance
ex. random “jiggling”
Internal energy “Heat”
Total energy produced by random motions of molecules and atoms; total kinetic energy of a sample
“Energy of random jiggling”
Conservation of Energy
Energy cannot be created or destroyed - it can only change forms
Temperature
Measures the average kinetic energy of molecule in a substance (related to average molecular speed)
~500m/s at room temperature
Heat Capacity
Amount of heat needed to raise the temperature of an object 1 degree Celsius
=> proportional to mass
=> Depends (somewhat) on composition
Specific Heat
Amount of heat needed to raise 1 gram of an object 1 degree Celsius
=> not proportional to mass
First Law of Thermodynamics: Ch
Change in Internal Energy =
Heat added to system
- Work done by system
Why is beach sand so hot on a sunny day, but the water stays comfortable?
Same amount of heat added to both, so same change in internal energy
Sun’s energy absorbed in 1 cm of sand
- Small mass, small heat capacity, large temperature change
Sun’s energy absorbed in 10 m of water
- large mass, large heat capacity, small temperature change
Second Law of Thermodynamics
Heat will transfer from a warm object to a cold object
Three modes of heat transfer
- Conduction
- Convection
- Radiation
Conduction
Heat transfer from molecule to molecule
Conductivity: Rate of heat transfer across object
Conduction
Katabatic winds: Winds caused by cool air sinking down a slope
Air next to surface cools via conduction / radiation
Cold / dense air sinks down the slope
Convection
Heat transfer via fluid motions (hot air rises, cold air sinks)
Buoyant plumes are called “thermals”
If most buoyant air is already on top, convection does not occur (stable situation)
Advection
Heat transfer via horizontal fluid motion
Heat transfer via horizontal fluid motion
Advection
Latent heat
Heat required for a substance to change phase
Ice => vapor
Sublimation
Vapor => Ice
Deposition
Vapor => liquid
Condensation
Liquid => vapor
evaporation
Why does evaporation cool liquid water?
Only the most energetic molecules break free of attraction to other molecules
Remaining molecules are “less jiggly” on average, so temperature decreases
Condensation is a source of energy for ___________ in clouds
rising air
Latent Heat: Source of energy for hurricanes
Water vapor evaporates from warm ocean surface
Water vapor condenses (latent heat release) into clouds/rain
Latent heat release provides source of energy for hurricane intensification
Radiation
Energy transfer by electro-magnetic waves
Dual personality: can be thought of as
- wave (electric and magnetic field)
- packet of photons (photon: a discrete bundle of energy)
*Ultimate source of energy (from Sun) to Earth
Wavelength
Distance between crests of electromagnetic radiation
Hotter objects emit more ______________
radiation
*Stefan-Boltzman
Wien’s law
Hotter objects => shorter wavelengths
Sun => “shortwave” radiation
Colder objects => longer wave lengths
Earth => longwave radiation
*warmer objects have maximum emission at shorter wavelengths
The Sun radiates more energy with _________ wavelengths
short
The Earth radiates more energy with _________ wave lengths
long
Fate of Incoming solar radiation
- Absorption
- Scattering
- Reflection
Absorption
Incoming radiation absorbed by molecule or particle in the atmosphere (or at the ground)
Scattering
Incoming radiation interacts with molecules or particles in the atmosphere and is sent in all directions
Reflection
Incoming radiation reflects back to space
Albedo - fraction of radiation that gets reflected
Albedo
Fraction of radiation that gets reflected
= Amount of reflecting radiation / Amount of incoming radiation
Bright (ice, snow) => High albedo
Dark (wet dirt, water) => low albedo
Radiative Equilibrium
Balance between incoming shortwave and outgoing longwave radiation
Shortwave absorbed = longwave emitted
Radiative equilibrium temperature:
Temperature required for radiative equilibrium
Selective Absorption
Capability of greenhouse gases in the atmosphere to absorb and emit longwave radiation, but only at selected wavelengths
The Greenhouse Effect
Sun-to-Earth
Shortwave radiation from the sun is trasmitted through the Earth’s atmosphere, and absorbed at the surface
The Greenhouse effect
Earth-to-atmosphere
Earth radiates energy to the atmosphere
Some passes through, but most is absorbed by the atmosphere, warming the atmosphere
Also, energy is transferred to the atmosphere via convection, warming the atmosphere
The Greenhouse Effect
Atmosphere
Energy is radiated back to earth and to space
Additional energy available to warm the surface
Thre Greenhouse Effect Equation
Shortwave absorbed (solar) + Longwave absorbed (atmosphere) = Lonwave emitted (earth)