Chapter 2 Energy: Warming the Earth and Atmosphere Flashcards
what is energy? what is the difference between potential and kinetic energy?
the ability to do work on some form of matter
- potential energy is the potential for work
- kinetic energy is energy of a moving object
what is temperature?
the average speed of atoms and molecules (average kinetic energy)
-average speed of molecules in thermosphere is very high because they move fast because there are fewer molecules overall. the thermosphere has the highest temp but it’s not hot
what is heat?
energy in the process of being transferred from one object to another because of difference in temp
-the total kinetic energy of all the atoms in a substance
what is the difference in motion between cold and warm air?
cold air: denser, moves slow, crowds closer/compacts
warm air: less dense, moves fast = expand
what are the different temperature scales?
Kelvin: 0=no motion, 273K=FP, 373K=BP
Celsius: 0=FP, 100=BP
Fahrenheit: 32=FP, 212=BP
what is heat capacity?
ratio of the heat energy absorbed to the resulting temperature change
what is specific heat?
the heat capacity divided by mass
-high specific heat equates to slow warming and vice versa
what is latent heat?
heat lost/gained with change of state, the energy needed to break bonds to move onto next state
- added going from solid→liquid→gas
- take heat from surrounding area=cooling
- lost going from gas→liquid→solid
- give heat to surrounding area=warming
what is conduction?
heat transferred from molecule to molecule
- energy travels from hot to cold
- greater change in temp=faster transfer
*air has low conductivity, doesn’t transfer heat very well
what is convection?
transfer of heat through a fluid (vertically)
- warm=less dense=rising
- cold=more dense=sinking
*advection is same process but horizontally
what is radiation?
energy transfer w/o a medium, in a wave
- frequency=# of waves that pass
- all objects with a temperature greater than 0K radiate energy
what does the Stefan-Boltzmann Law say?
hotter object=more energy it emits, and vice versa
E =σT4 (energy emitted is proportional to the fourth power of emitter’s absolute temperature
what does Wien’s Law say?
hotter object=shorter wavelength, and vice versa
λmax of sun= 0.5 μm (visible)
λmax of earth=10 μm (infrared)
what does radiative equilibrium mean?
the earth emits out as much as the run emits in. However, the outgoing IR energy is absorbed by GHGs to keep the earth warm.
Absorb > emit = warm
Emit > absorb = cool
what are selective absorbers?
they selectively absorb and emit radiation. GHGs (H2O, CH4, CO2) let in shortwaves and absorb infrared from earth. only absorb UV and IR, not visible from sun
