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Mechanisms of Energy Transfer (Heating):
(Heat describes energy flow from hot -> cold, not amount of energy and object has)
Conduction: Transfer of kinetic or vibrational energy by direct molecular collisions. What could maximize conduction efficiency?
Convection: Spontaneous transfer of thermal energy by turbulent mixing in fluids. What conditions might maximize convection?
Radiation: Transfer of energy by electromagnetic waves. Only mechanism that doesn’t need a medium for transfer. What could prevent radiative transfer?
?
How does direct radiation from the sun warm a cup of water (PS 2) ?
TmcQ
a)(power/aredensity radiation solar incoming2m
W
A
P
Q(in J)=Total Energy= Power x time x area
P( in W) = Power = Energy / time
1AtA
PQ
cm
AtA
P
T1
Simple Thermodynamic Relationships
Assumptions in calculating Temp. warming:
•No significant net heat lost by conduction, convection, or radiation (this is BS except for rare special circumstances)
•All incident solar radiation is absorbed (or reduced by known albedo)
•Uniform temperature of object
Substance Phasecp
J g−1 K−1
Air (Sea level, dry, 0 °C) gas 1.0035
Air (typical room conditionsA) gas 1.012
Aluminium solid 0.897
Ammonia liquid 4.700
Copper solid 0.385
Diamond solid 0.5091
Gasoline liquid 2.22
Gold solid 0.1291
Graphite solid 0.710
Iron solid 0.450
Lead solid 0.127
Lithium solid 3.58
Magnesium solid 1.02
Mercury liquid 0.1395
Nitrogen gas 1.040
Oxygen gas 0.918
Paraffin wax solid 2.5
Silica (fused) solid 0.703
Uranium solid 0.116
Water
gas (100 °C) 2.080
liquid (25 °C) 4.1813
solid (0 °C) 2.114
Typical Heat Capacities:
Average Emitted infrared radiation
Incoming solar radiation for August
Solar radiation absorbed yesterday
August solar radiation absorbed by surface
Sea Surface Temperatures
Sea Surface Temperature Anomaly
