Flashcards in Midterm 1 Deck (18):
Differentiate b/w climate and weather.
weather is the state of the atmosphere in a short period of time, weather includes the temperature, humidity, and precipitation on the hourly scale.
climate s the atmospheric conditions over a long period of time. time averaged, is more perdictable
what is the main variable used to describe global warming?
The main variable describing global warming is surface temperature averaged over earth in centuries
list and describe the paleoclimate proxies?
sediment cores - taken from marine sediment , thickness of sediments and organic composition of the deposits can be used to infer about the past climate.
Pollen - well preserved, can provide info about the vegetation at that time, can infer past climates based on plant distribution
Tree rings - tree growth is influenced by climate and can be seen in ring width and isotopic composition.
Stable isotopes - the ratio of O18:O16 is influenced by climate
coral reefs - composed of calcium carbonate, can us oxygen ratio to predict the water temp and the location.
ice cores, aersols, ash layers and insolation can also be used
proxies for temp and CO2 proxies
temp. - deuterium isotopes, ice cores, marine sediments
CO2 - ice cores
differentiate b/q mechanics and thermodynamic
mechanics considers one particle while thermodynamics considers multiple
a mixture of electrons and cations at very high temp
what is heat?
a form of energy indicated by Q.
What are the methods for heat transfer?
Conduction refers to heat exchange, where high speed particles are colliding with low speed particles, until eventually approximately all particles are travelling at the same speed.
Convection is heat transfer by motion of a fluid (either water or gas) , where the heated fluid is moving away from the source of heat through bulk motion. Radiation is the transfer of heat by electromagnetic waves, carrying energy from origin to spaces around it
Define a black body
any object that is a perfect emitter and absorber of radiation, will absorb and emit all radiation it comes in contact with
Stefan - Boltzmann law
F = σT4. It gives the total energy being emitted at all wavelengths by the blackbody, the area under the Planck Law.
two principles: all objects emit radiant energy proportional to the temp raised to the 4th
the energy flux from the sun at the earth's mean distance from the sun
two systems in contact will come to the same temperature after a period of time, all objects want to be in a state of equilibrium
what is albedo?
the percent of energy reflected away from an object, for the earth it is 0.306 and for mercury it is 0.068
why do we need albedo?
b/c the atmosphere is gaseous, they cannot be approximated as black bodies, not all the solar radiation will reach the surface.
first lay of thermodynamics
the change in the internal energy of a system is equal to the heat added or lost and the work done on the system.
grey vs black body
BB absorbs all radiation grey absorbs a fraction and emits a fraction. it may transmit and reflect some
F = εσ T4