Chapter 2: The Global Ledger Of Heat Energy

Front 1

Speed of light

Back 1

150,000,000 km or 93,000,000 mi

Front 2

Solar Radiation

Back 2

An ensemble of visible and invisible energy emitted by the sun

Front 3

Terrestrial radiation

Back 3

Radiation emitted by the earths surface and atmosphere

Front 4

What emits radiation

Back 4

Everything

Front 5

Electromagnetic field (EMF)

Back 5

Forms anywhere electrical charges are in motion

Every atom has an EMF - negatively charged electrons orbit a nucleus of neutrons and positive protons

Front 6

Electromagnetic radiation

Back 6

Occurs when an electron oscillates sending out ripples of energy with electric/magnetic properties

Faster oscillation = higher temperature

Front 7

Wavelength

Back 7

The distance between the crest of one wave and the crest of the next wave

Front 8

Electromagnetic spectrum

Back 8

The entirety of wavelengths of radiation from the smallest to the largest

Front 9

Visible radiation

Back 9

The narrow range of wavelengths between approx. 0.4 and 0.7 micrometers (or microns (1 um = 0.000001 m)) that can be seen with the naked eye

Front 10

Wavelength associated with violet

Back 10

0.4 um

Front 11

Over exposure to short wavelength radiation can cause

Back 11

Cancer, cataracts etc

Front 12

Practical use of gamma-rays

Back 12

The airborne snow survey program -> Detecting water content/amount of snowfall in remote areas by plane/possibility of flooding in spring -> the more water the less radiation

Front 13

Every object emits some radiation

Back 13

At ALL wavelengths; however, every object has a wavelength at which it emits peak radiation

Where the wavelength of peak emission lies on the spectrum depends solely on the temperature of the object

Front 14

The hotter an object

Back 14

The shorter the wavelengths of peak radiation it emits

Front 15

Stefan-Boltzmann Law

Back 15

The amount of energy emitted by an object, per unit area (E), is proportional to the object's temperature in Kelvins (T) raised to the fourth power.

E = (sigma)T4

Front 16

The sun emits about 45% of it's radiation as

Back 16

Visible wavelengths & about 90% of its energy at wavelengths less than 1.5 um.

Peak emission = approx 0.5 um (blue-green sensation)

Front 17

Terrestrial objects emit most of their radiation at

Back 17

Infrared wavelengths

Earth peak radiation is approx 10 um.

Front 18

Three fates of emitted electromagnetic radiation

Back 18

Absorption, transmission, & scattering

Front 19

the angle at which radiation impinges upon an object

Back 19

Helps determine how much is ultimately available to absorb, transmit, or scatter.

The more direct the angle the more intense the radiation/efficient heating

Front 20

Absorptivity

Back 20

In the visible range of wavelengths, the fraction of energy absorbed by an object (depends in part on it's color)

Darker color = more visible radiation absorbed

Front 21

Absorptive of invisible wavelengths of radiation

Back 21

Depends on factors such as molecular structure

Front 22

Snow absorbs

Back 22

Infrared radiation / not visible light

Snow reflects solar radiation

Front 23

Transmission of radiation

Back 23

Means that there is no diminishing of the intensity of radiation as it passes through the object

Front 24

Solar radiation striking the earth at an angle of 10 degrees must pass through

Back 24

Nearly 6 times as much atmosphere

Front 25

Solar radiation striking the earth at an angle of 10 degrees must pass through

Back 25

Nearly 6 times as much atmosphere

Front 26

Most objects absorb

Back 26

At least some of the radiation that hits them

Front 27

Solar radiation striking the earth at an angle of 10 degrees must pass through

Back 27

Nearly 6 times as much atmosphere

Front 28

Most objects absorb

Back 28

At least some of the radiation that hits them

Front 29

Objects that absorb more energy than they emit usually undergo

Back 29

A net warming: they warm more from the energy gained by absorption than they cool from the energy lost from emission

Front 30

Objects that radiate more than they absorb usually undergo

Back 30

Net cooling

Front 31

Objects that radiate more than they absorb usually undergo

Back 31

Net cooling

Front 32

Objects that absorb and radiate equal amounts of energy

Back 32

usually experience no change in temperature (we say usually because the presence of water complicates matters)

Front 33

Objects that radiate more than they absorb usually undergo

Back 33

Net cooling

Front 34

Objects that absorb and radiate equal amounts of energy

Back 34

usually experience no change in temperature (we say usually because the presence of water complicates matters)

Front 35

Regions within about 35 degrees of the equator receive a net

Back 35

Surplus of radiation

Front 36

Objects that radiate more than they absorb usually undergo

Back 36

Net cooling

Front 37

Objects that absorb and radiate equal amounts of energy

Back 37

usually experience no change in temperature (we say usually because the presence of water complicates matters)

Front 38

Regions within about 35 degrees of the equator receive a net

Back 38

Surplus of radiation

Front 39

Latitudes closer to the poles receive a net

Back 39

Loss of energy

Front 40

The difference in net radiation between the polar and equatorial regions sets in motion

Back 40

General Circulation... A pattern of winds in the troposphere and currents in the oceans that helps to partially mitigate the energy imbalance

Front 41

Solar constant

Back 41

1367 Watts per square meter

Front 42

Albedo

Back 42

30 out of 100 units of energy are reflected back to space, predominately by air molecules and clouds (because the earth reflects 30% of the solar radiation inflicted upon it, we say the earth has a planetary albedo of 0.30)

Front 43

Troposphere

Back 43

The lowest layer (10km or 6mi) of atmosphere where the sun's energy on average decreases with height

Front 44

The sun warms

Back 44

The ground and the ground warms the air

Front 45

Downwelling radiation

Back 45

The downward emission of infrared radiation by clouds

Front 46

Air parcels

Back 46

Blobs of air (carry ground-warmed pockets of air skyward)

Front 47

Convection

Back 47

Limits the thickening of the layer of very hot air in contact with the ground on a sunny , hot day

Front 48

Positive bouyancy

Back 48

Things that float on water have a positive bouancy

Front 49

Negative bouyancy

Back 49

Things that sink

Front 50

Density

Back 50

The mass/weight of an object divided by its volume

Front 51

Temperature is the primary control of

Back 51

Air density (as temp increases molecules move faster and naturally occupy a greater space or volume so the density of the warmer air is less than the density of the cooler air)

Front 52

On a summer day, the sun heats the ground and the thin layer of air above it, some spots greater than others. Over the hotter area the air is more

Back 52

Positively bouyancy, rising and giving way to convection

Front 53

Manifestations of convection include very tall cumulonimbus clouds that produce lightning and thunder

Back 53

To the invisible thermals that Hawks and hang-gliders routinely ride on

Front 54

Convection is responsible for

Back 54

Cloud formation by bouyant parcels of rising air

Front 55

Schlieren photography

Back 55

Captures invisible thermal convection

Front 56

Clouds at night act more like

Back 56

Space heaters, emitting much more infrared radiation than a clear sky emits (surface temps tend to be higher on cloudy nights)

Front 57

Clouds at night act more like

Back 57

Space heaters, emitting much more infrared radiation than a clear sky emits (surface temps tend to be higher on cloudy nights)

Front 58

Eddies

Back 58

Turbulent swirls of air (an ideal eddy circulates warm air upward and cooler air downward, relaxing large temperature gradients near the ground/mixing the air)

Front 59

Eddies can develop simply when

Back 59

The wind blows over the earth's rough surface, creating a different form of convection in which the catalyst is not the warm ground

Front 60

Eddies can develop simply when

Back 60

The wind blows over the earth's rough surface, creating a different form of convection in which the catalyst is not the warm ground

Front 61

Mechanical convection

Back 61

With faster winds blowing over slower winds due to less friction further from the earth's surface, eddies develop in a mechanical way

Front 62

On a windy night, the downward circulation by mechanical eddies transports relatively warmer air toward the ground, preventing a big nocturnal chill from forming

Back 62

On a windy sunny day, mechanical eddies help to lessen the temperature gradient near the surface by circulating warm air rapidly away from the ground just like eddies driven by thermal convection

Front 63

The atmosphere is warmed more by

Back 63

The ground than the sun

Front 64

The earth's surface received nearly double the energy from our atmosphere than it does from the sun

Back 64

Without clouds and greenhouse gases to trap the energy the earth's temperature would be drastically lower

Front 65

Because of their small size, air molecules scatter shorter wavelengths more than longer wavelengths

Back 65

Which our brain interprets as sky blue