Chapter 2 Notes
= change in speed or a change in directions of objects movement
done on an object, distance traveled times the force in the direction of
the capacity to do work.
Forms of Energy
work that a body can do by virtue of its motion.
work an object can do as a result of its relative position, represents
stored energy that can be converted to other energy forms
a measure of the average kinetic energy of a substance
unit used to measure energy, the energy needed to raise the temp of 1 gram
of water 1 degree Celsius
unit used to measure energy
the rate at which energy is transferred, received, or released.† Units for power are Watts (transfer of 1
joule of energy per second)
the energy produced by the random motions of molecules and atoms, the
total kinetic energy of a sample of a substance.† Also, could be defined as the energy
transferred between objects as a result of the temperature difference
Heat- a low specific heat means a substance warms and cools easily, a high
specific heat means it takes a lot of energy to change the temperature.
Methods of Energy Transfer
the process of heat transfer from molecule to molecule, requires
contact,††† Example: when we touch
something to see if it is warm or cold
ability of a substance to conduct heat by molecular motions is its
thermal conductivity (wood has low conductivity, metal has high
conductivity).† Conduction not
efficient for transferring energy on a global scale, only over small
the process of transferring energy vertically.
over deserts in the summer due to warming of sand.† Inefficient mode of transfer in the
poles due the surface air being cooler than the air above.
Advection- horizontal transport of energy in the atmosphere
Advection- when warm air replaces cooler air.† Cold advection is the opposite.
Heating- the heat absorbed or released per unit mass when water changes
heat of melting- energy absorbed by water to change ice to liquid water
heat of fusion- amount of energy released to the environment when water
heat of vaporization- amount of heat required to evaporate liquid water
heat of condensation- the amount of energy released when water vapor
condenses to liquid form
Phase change from gas to solid
Phase change from solid to gas
Evaporation, and Melting are all cooling processes (removes energy from
Freezing, and Deposition are warming processes (add energy to atmosphere)
Radiative Heat Transfer
energy in the form of waves that are not composed of matter
characterized by two properties: Wavelength (distance b/tw wave crests),
Amplitude (half the height from the peak of the crest to the lowest point
of the wave)
Law- all objects with a temperature above absolute zero emit radiation.
warmer object emits more radiation that a cold object.
Law- the hotter the object, the shorter the wavelength of maximum emission
radiation interacts with an object it can be: Absorbed, Reflected, or
describes the percentage of light an object reflects (Snow has high
amount of radiation energy the atmosphere absorbs depends on radiative
properties of the material, amount of time exposed to energy, the amount
of material, the proximity to the energy source, and the angle at which
an object that absorbs all the electromagnetic energy that falls on the
Law- a good absorber of radiation is also a good emitter of radiation at
that same wavelength.
Sun and Seasons
Earthís tilt, not the distance from the sun, causes the seasons.
tilt is referred to as the angle of inclination.
the Earth orbits around the sun in an ellipse shape, the distribution of
sunlight changes on the Earthís surface at a given latitude.
Sunís rays strike the equator at an angle of 23.5 degrees (June 21, Dec
Sunís rays strike the equator at an angle of 90 degrees (March 21, Sept.
22) --† All locations on Earth
experience both 12 hours of daylight and darkness.
Zenith Angle- the angle at which the Sunís energy strikes a particular
location on Earth.† (0 degrees when
Sun is directly overhead and increases as Sun sets until Sun is on the
horizon and the angle is 90 degrees). †
larger zenith angle means more solar energy is distributed over a larger
area, thus it receives less energy.†
This is because the Sunís energy must pass through more atmosphere,
giving solar energy more change of atmospheric absorption.
further poleward you travel, the more daylight you have during the summer
and the fewer daylight hours in the winter.†
Radiative Properties of the Atmosphere
gases are selective in the solar wavelengths that they absorb.
atmospheric window (10-12 micrometers spectral region) allows the Earth to
cool off and emit its energy to outer space.
are good reflectors of solar energy, and they are good emitters and
absorbers of longwave energy.
Greenhouse Effect- It is caused by the Earthís surface being heated by
shortwave and longwave absorption emitted by gases (such as water vapor
and CO2) in the atmosphere.† If it
did not occur, the Earth surface would be 60 degrees F cooler than it is
enhanced Greenhouse effect is used to explain the relationship between the
observed rise in global temperatures and an increase in atmospheric carbon
carbon dioxide produces more infrared energy being absorbed which warms
the atmosphere.† The now-warmer
atmosphere will then emit more longwave energy than it did previously and
will increase the longwave energy hitting the Earthís surface warming it
gases are transparent to solar energy and absorb terrestrial energy and
warm the atmosphere b/c they allow solar energy to reach the surface and
inhibit longwave radiation from going to space. (Ex: water vapor, CO2,
Balance- when the energy losses equal the energy gains
tropics gain and the poles lose radiant energy on a yearly basis, so the
energy must be transported between the tropics to the poles to balance
each other.† This transport is done
through the atmosphere and ocean currents and is major reason for weather
Transfers- Sensible and Latent Heat transfers