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