Energy

Question 1

define work

Answer 1

energy that is transferred when matter is
pushed, pulled or lifted

Question 2

define energy

Answer 2

the capacity to do work on some form of matter

Question 3

what forms do energy come in

Answer 3

1. potential (gravitation, chemical, nuclear, . . . )
2. kinetic (electrical, mechanical, magnetic, . . . )

Question 4

what is the first law of thermodynamics

Answer 4

Energy is neither created nor destroyed; it is conserved
and can be converted from one form to another.

Question 5

definition of potential energy

Answer 5

Energy stored in an object that determines how much
work it is capable of doing due to the force of gravity
PE = m × g × h
where m = mass (kg)
g = acceleration due to gravity
h = height above a reference level (m)

Question 6

definition of kinetic energy

Answer 6

Energy of a moving object
KE = 1/2 x mv^2

Question 7

molecules that have kinetic energy referred to as …

Answer 7

heat energy

Question 8

definition of internal energy

Answer 8

Microscopic energy including its translational kineticenergy, vibrational and rotational kinetic energy and potential energy from intermolecular forces

Question 9

definition of chemical energy

Answer 9

Energy stored in bonds of chemical compounds
eg) batteries and wood store chemical energy

Question 10

definition of radiant energy

Answer 10

Energy of electromagnetic waves (photons). All matter with a temperature above absolute zero emit radiant energy.

RE = hc/lambda
h = planck’s constant = 6.626 x 10^-34 J s
c= speed of light = 3 x 10^8 ms^-1
lambda = wavelength of electromagnetic wave

Question 11

definition of temperature

Answer 11

The average kinetic energy of the atoms and molecules in a substance.

Question 12

definition of heat

Answer 12

Heat is energy in the process of being transferred from one object due to the temperature difference between them.

Question 13

how is energy stored once heat is transferred from one object to another

Answer 13

it is stored as internal energy

Question 14

what are the two different forms of heat

Answer 14

1. sensible
2. heat

Question 15

definition of sensible heat

Answer 15

energy associated with the kinetic energy of molecules and atoms

Question 16

definition of latent heat

Answer 16

energy associated with thermodynamic phase changes of a substance

Question 17

describe latent heat

Answer 17

An important source of
atmospheric energy
* Water vapour evaporated
from Earth’s surface rises to
higher altitudes (i.e.
heights) with colder
temperatures
* Condensation of water
vapour and freezing or
deposition to form ice
release latent heat to the
environment that drives
thunderstorms, hurricanes,
mid-latitude cyclones

Question 18

what is exothermic

Answer 18

a process that releases energy from the system to the surroundings

freezing, condensation, deposition

Question 19

what is endothermic

Answer 19

a process that absorbs energy from its surroundings so that heat is transferred to the system

melting, evaporation, sublimation

Question 20

definition of heat capacity

Answer 20

The heat capacity of a substance is the ratio of the amount of heat energy absorbed by that substance to its corresponding temperature rise

Question 21

definition of specific heat

Answer 21

the heat capacity of the substance per unit mass, i.e. the amount of heat needed to raise the temperature of one gram of the
substance by one °C.

Question 22

what are the three main mechanisms heat is transferred by in Earth’s atmosphere

Answer 22

1. conduction
2. convection
3. radiation

Question 23

definition of conduction

Answer 23

Molecular transfer of heat from warm to cold regions

Question 24

definition of thermal conductivity

Answer 24

measure of how
efficiently it transfers heat
by molecular motion

eg) air is an extremely poor conductor of air and is therefore used as an insulator

Question 25

definition of convection

Answer 25

Transfer of heat through a fluid caused by motion To conceptualize convection, imagine a “parcel" of air — an invisible balloon-like “blob" of air that can expand/contract but does not exchange heat with the environment (adiabatic process) and has the same pressure as the environment at a given height The air parcel’s vertical motion is determined by its density, which is determined by its temperature and water vapour content

Question 26

describe adiabatic expansion

Answer 26

As the air parcel lifts, environmental air pressure drops * air parcel uses internal energy to do work to expand, which decreases the kinetic energy of its molecules * air parcel cools

Question 27

describe adiabatic compression

Answer 27

As air parcel descends, environmental air pressure increases * environment does work on air parcel and compresses it, increasing the kinetic energy of the molecules and therefore internal energy of the parcel * air parcel heats

Question 28

definition of advection

Answer 28

The transfer of air properties (temperature, moisture) by wind in the atmosphere. U · ∇T , where U = wind velocity [ms−1], T = temperature [K] stronger wind, a larger temperature gradient and/or smaller angle between wind direction and temperature gradient maximize the strength of advection

Question 29

definition of radiation

Answer 29

Emission of energy in the form of electromagnetic waves or particles through space or material. * All matter with a temperature above absolute zero emit electromagnetic radiation * Radiation does not require a medium to propagate, unlike the transfer of energy via conduction or convection

Question 30

properties of waves

Answer 30

wavelength (lambda), speed (v=c), and frequency (f) c = f λ

Question 31

on the electromagnetic spectrum, where does the sun radiate?

Answer 31

the sun radiates mostly in the visible spectrum, but also in the UV and near-infrared (IR) part of the electromagnetic spectrum

Question 32

once the sun's beam enters the earth's atmosphere, it ...

Answer 32

can be scattered, absorbed or reflected

Question 33

describe scattering

Answer 33

occurs when sunlight is deflected in all directions upon striking air molecules when sunlight is scattered by molecules that are smaller in diameter than its wavelength, the molecules scatter shorter wavelengths more effectively - more evenly (Rayleigh scattering) when sunlight is scattered by molecules that are about the same wavelength as the size of the molecules, the molecules scatter more in the forward direction (Mie Scattering)

Question 34

why is the sky blue?

Answer 34

The sky is blue because of Rayleigh scattering: small air molecules are more effective at scattering shorter wavelengths (blue colours)

Question 35

why are clouds white?

Answer 35

Clouds are white because of Mie scattering: large cloud droplets effectively scatter all wavelengths of visible light from the sun (which is white) in all directions

Question 36

why is the sunset red?

Answer 36

Sunsets are red because when the sun sets, the sun is further away from the atmosphere, implying that its beam needs to travel a greater distance to Earth’s atmosphere, scattering shorter blue wavelengths along the way

Question 37

definition of albedo

Answer 37

The fraction of incident shortwave radiation that is reflected back to space. the albedo is a measure of how "bright" an object is

Question 38

what objects have high albedos?

Answer 38

low-level liquid clouds, sea ice or snow-covered surfaces and deserts

Question 39

on average, what is earth's albedo?

Answer 39

0.3 - 30%

Question 40

definition of a blackbody

Answer 40

Any object that is a perfect absorber (i.e. absorbs all the radiation that strikes it) and a perfect emitter (i.e. emits the maximum radiation possible at its given temperature). the emissivity is the ratio of the energy radiated from a material's surface to that radiated by a blackbody

Question 41

what two objects can be treated as blackbodies to good approximation?

Answer 41

the sun and earth

Question 42

describe Planck's law

Answer 42

- relates to the distribution of spectral energy emitted by a blackbody as a function of wavelength at a given temperature - note that blackbodies with higher temperatures emit more radiation at all wavelengths

Question 43

what is Stefan-Boltzmann law?

Answer 43

The Stefan-Boltzmann law is the statement that the total radiant heat power emitted from a surface is proportional to the fourth power of its absolutetemperature * It is the integral of the Planck function F = σT 4

Question 44

describe Wien's displacement law

Answer 44

relates the temperature of a blackbody with the wavelength at which it emits the most radiation it is the peak wavelength of the Planck function confirms that the sun radiates at shorter wavelengths and the earth radiates at longer wavelengths

Question 45

what is Kirchoff's law?

Answer 45

states that good absorbers are good emitters at a particular wavelength, and poor absorbers are poor emitters at the same wavelength. implies that each material has a specific preference for the wavelength it absorbs and emits efficiently

Question 46

what is the greenhouse effect

Answer 46

greenhouse gases re-emitting infrared radiation back to the surface, warming earth's surface and lowering the atmosphere

Question 47

what are the three most abundant greenhouse gases in the atmosphere

Answer 47

1. carbon dioxide 2. methane 3. water vapor of these three greenhouse gases, methane is the most effective greenhouse gas

Question 48

how is radiative equilibrium achieved?

Answer 48

when incoming radiation is balanced by outgoing radiation

Question 49

how does the earth equilibriate radiative forcing?

Answer 49

by transferring heat to the poles

Question 50

describe arctic amplification

Answer 50

Earth’s arctic is particularly vulnerable to warming — 2-3 times the pace as the rest of the globe since the 1960s * Arctic amplification (AA) factor: the number of times the mean Arctic surface air temperature exceeds that of the globe or tropics * Winter and fall phenomenon * A combination of feedback processes contribute to AA; not only the sea ice albedo feedback