energy, temperature and heat - about...
TRANSCRIPT
Energy: The capacity to do work (or loosely, the potential to make something happen)● Energy can be transferred in the form of heat or radiation
(among other processes)
Power: The rate at which energy is transferred from one object to another (i.e., the energy per unit time)
Temperature: A measure of the energy associated with the motion and vibration of an object's molecules (loosely, a measure of the stored heat energy)
Heat: The energy transferred between objects because of differences in temperature
Energy, Temperature and Heat
Some loose definitions:
● An object with higher specific heat requires more heat to be added to produce a given change in temperature. Or stated a different way......
● For a fixed amount of heat added, an object with higher specific heat has a smaller temperature change.
Specific Heat
Given a gram of some substance, the amount of heat needed to raise the temperature by 1oC is the material's specific heat. Two ways you might look at this:
Specific Heat
Given a gram of some substance, the amount of heat needed to raise the temperature by 1oC is the material's specific heat. Two ways you might look at this:
Notable fact: the specific heat of water is roughly 2 to 5 times greater than the specific heat of land.
heat from sun
Specific Heat
Given a gram of some substance, the amount of heat needed to raise the temperature by 1oC is the material's specific heat. Two ways you might look at this:
Notable fact: the specific heat of water is roughly 2 to 5 times greater than the specific heat of land.
low specific heat, bigger temperature change
high specific heat, smaller temperature change
heat from sun
The difference in the specific heats of land and water is responsible for the sea breeze.● During the day, the cooler, heavier air over the water
undercuts the warmer, lighter air over land● The boundary where the cooler and warmer air meet is
called the sea breeze front
cooler airwarmer
air
sea breeze front
lake breezes over Michigan
The difference in the specific heats of land and water is responsible for the sea breeze.● During the day, the cooler, heavier air over the water
undercuts the warmer, lighter air over land● The boundary where the cooler and warmer air meet is
called the sea breeze front
rising air at the sea breeze front often leads to thunderstorms
The difference in the specific heats of land and water is responsible for the sea breeze.● During the day, the cooler, heavier air over the water
undercuts the warmer, lighter air over land● The boundary where the cooler and warmer air meet is
called the sea breeze front
Radiation: Basic Concepts
Radiation refers to energy transmitted by electromagnetic waves (or waves of electric and magnetic force)● Radiation differs from heat in that it travels from emitter to
absorber without affecting the intervening space
SunEarth
emitter
absorber
no effect on intervening space
Radiation refers to energy transmitted by electromagnetic waves (or waves of electric and magnetic force)● Radiation differs from heat in that it travels from emitter to
absorber without affecting the intervening space
● Radiation is classified by its wavelength (or peak-to-peak distance), often denoted by λ
λ- Typical units range from
micrometers (m) to meters (m), with
1 m = 10-6 m
Radiation: Basic Concepts
electromagnetic waves classified by wavelength
Category Wavelength
TV, radio ~ 1 to 100 m
microwave ~ 0.1 to 1 cm
infrared (IR) ~ 1 to 100 m
visible ~ 0.4 to 0.7 m
ultraviolet ~ 0.1 m
gamma-ray, X-ray < 0.1 m
electromagnetic waves classified by wavelength
Category Wavelength
TV, radio ~ 1 to 100 m
microwave ~ 0.1 to 1 cm
infrared (IR) ~ 1 to 100 mvisible ~ 0.4 to 0.7 m
ultraviolet ~ 0.1 m
gamma-ray, X-ray < 0.1 m
electromagnetic waves classified by wavelength
All substances continuously emit and absorb radiation● The wavelengths emitted / absorbed depend on both the
temperature and properties of the object's surface
● Emission and absorption are characterized in terms of
Emission spectrum: The energy emitted by an object as a function of wavelength
the emission spectrum of
the sun
All substances continuously emit and absorb radiation● The wavelengths emitted / absorbed depend on both the
temperature and properties of the object's surface
● Emission and absorption are characterized in terms of
Absorption spectrum: The fraction (or percentage) of incident energy absorbed by an object as a function of the wavelength
the absorption spectrum of
CO2
All substances continuously emit and absorb radiation● The wavelengths emitted / absorbed depend on both the
temperature and properties of the object's surface
● Emission and absorption are characterized in terms of