BIOL 320 Ecology Exam 2
MODULE 5
Energy Balance
What is the primary source of heat gain for this organism?
radiation from the sun
What is the greatest source of heat loss for this organism?
Contrast two environments: one that you find too cold and
another that you find too hot.
What factors contribute to how cold to hot these
environments make you feel?
Too cold:
-low radiation
-cold or moving air (produces more convective heat loss)
-low humidity (lose heat to evaporation)
Too hot:
-intense radiation
-warm or still air (produces less convective heat loss)
-high humidity (cannot sweat effectively)
heat flux
exchange transfer of thermal energy
,model of heat balance
Left side: heat gain
Right side: heat loss
Q met = the quantity of heat gained by metabolism
Q rad_absorbed = the quantity of heat gained from absorbing
radiation
Q rad_emitted = the quantity of heat loss from emitting
radiation
Q cond = the quantity of heat flux by conduction
Q conv = the quantity of heat flux by convection
Q evap = the quantity of heat loss from evaporation
Q stored = the quantity of heat stored when heat gain differs
from heat loss
Processes by which organisms exchange heat with their
environment
-Radiation
-Conduction
-Convection
-Evaporation
All these sources of heat gain and loss can occur
simultaneously
Radiation
, emission of electromagnetic energy by a surface
=>primary source: the Sun
can occur as direct sunlight, sunlight that has been scattered
from interacting with gas molecules in the atmosphere, or
sunlight reflected from clouds and the ground
solar radiation warms objects and the objects emit lower-
energy radiation in the form of infrared light
temperature (K) of the radiating surface determines how
rapidly an object loses energy by radiation to colder parts of
the environment
The amount of heat radiation increases with the fourth
power of absolute temperature (K).
0°C = 273°K
Modeling Radiation
radiate energy according to their temperature
KE converts to electromagnetic photons that travel outward
until they strike another molecules
molecular motion increases (object warms) when a molecule
absorbs photons
equation:
-A: equals the surface area of the object emitting radiation
(m^2)
MODULE 5
Energy Balance
What is the primary source of heat gain for this organism?
radiation from the sun
What is the greatest source of heat loss for this organism?
Contrast two environments: one that you find too cold and
another that you find too hot.
What factors contribute to how cold to hot these
environments make you feel?
Too cold:
-low radiation
-cold or moving air (produces more convective heat loss)
-low humidity (lose heat to evaporation)
Too hot:
-intense radiation
-warm or still air (produces less convective heat loss)
-high humidity (cannot sweat effectively)
heat flux
exchange transfer of thermal energy
,model of heat balance
Left side: heat gain
Right side: heat loss
Q met = the quantity of heat gained by metabolism
Q rad_absorbed = the quantity of heat gained from absorbing
radiation
Q rad_emitted = the quantity of heat loss from emitting
radiation
Q cond = the quantity of heat flux by conduction
Q conv = the quantity of heat flux by convection
Q evap = the quantity of heat loss from evaporation
Q stored = the quantity of heat stored when heat gain differs
from heat loss
Processes by which organisms exchange heat with their
environment
-Radiation
-Conduction
-Convection
-Evaporation
All these sources of heat gain and loss can occur
simultaneously
Radiation
, emission of electromagnetic energy by a surface
=>primary source: the Sun
can occur as direct sunlight, sunlight that has been scattered
from interacting with gas molecules in the atmosphere, or
sunlight reflected from clouds and the ground
solar radiation warms objects and the objects emit lower-
energy radiation in the form of infrared light
temperature (K) of the radiating surface determines how
rapidly an object loses energy by radiation to colder parts of
the environment
The amount of heat radiation increases with the fourth
power of absolute temperature (K).
0°C = 273°K
Modeling Radiation
radiate energy according to their temperature
KE converts to electromagnetic photons that travel outward
until they strike another molecules
molecular motion increases (object warms) when a molecule
absorbs photons
equation:
-A: equals the surface area of the object emitting radiation
(m^2)
