Radiation

Question 1

name 3 things that happens to the solar radiation as its transmitted through earths atmosphere between the atmosphere and ground?

Answer 1

scattering

reflection and absoption of short wave radiation

emittance of long wave radiation

Question 2

what is solar energy?

Answer 2

radiant light and heat energy emitted by the sun

Question 3

What is short wave radiation?

Answer 3

UV - visible light

shorter wavelength

Question 4

how much energy does SWL have?

Answer 4

lots

Question 5

where does SWL come from?

Answer 5

The sun emits SWL radiation which is directly diffused/ scattered , reflected or absorbed

Question 6

What is Long wave radiation?

Answer 6

infrared

longer wavelength

Question 7

how much energy does LW radiation have?

Answer 7

less energy than SW

Question 8

Where does LW radiation come from?

Answer 8

the ground heats up and re emits as long wave radiation as infrared

Question 9

define albedo

Answer 9

the reflectivity of a material

Question 10

how can albedo be calculated?

Answer 10

ratio of outgoing radiation and incoming SW radiation

Question 11

what does it mean by reflected?

Answer 11

bounces off something and goes in another direction eg a tree

everything we see has light reflecting off it - thats why we cant see very well in dark room

Question 12

what things cause reflection

Answer 12

reflection by ground surface

reflected by clouds

diffuse reflection

Question 13

what type of reflection do natural surfaces get?

Answer 13

diffuse reflection as they are rough and energy scattered away from surface

(smooth surfaces have purer reflection when angle of incidence approaches angle of reflection)

Question 14

what is the albdeo of a perfectly black surface?

Answer 14

zero
no reflection
absorbing

Question 15

what is the albedo of a perfectly white surface?

Answer 15

1
complete reflection
no absorbing

Question 16

do smooth surfaces increase or decrease albedo ?

Answer 16

increase albedo
(rough surfaces decrease albedo)

Question 17

how many grey tones can the eye detect?

Answer 17

20

Question 18

When will liquid water have a high albedo?

Answer 18

when suns angle is very low eg sunrise
the angle is low and radiation will be reflected by water
this is why high latiudes reflect more sola radiation (also due to albedo)

Question 19

When will liquid water have a low albedo?

Answer 19

when sun is above horizon

it absorbs SR

Question 20

snow and cloud albedo??

Answer 20

high albedo as white and smooth (clouds vary)

0.4-0.9

Question 21

sand, dry soil and ice albedi???

Answer 21

darker surface and less smooth so lower albedo than snow

0.3-0.4

Question 22

vegetation and water albedo???

Answer 22

darker and rough surfaces so have low albedo

0.0 - 0.25

Question 23

what places have the highest albedo?

Answer 23

snow covered areas like antarctica

cloud cover

(high albedo correlates to places with highest Sw radiation being reflected back to space)

Question 24

what could scatter radiation into atmosphere ?

Answer 24

gases
particulates - dust
water droplets - clouds

Question 25

what is diffuse insolation?

Answer 25

shortwave radiation that has been scattered without altering wave length

Question 26

what % of reflectivity or albedo does scattering account for?

Answer 26

7% | depends on size of molecules being scattered

Question 27

what determines the colour of light?

Answer 27

the wavelength

Question 28

Define scattering

Answer 28

the process which electromagnetic radiation or particles are deflected or diffused it depends upon the size of molecules/particles it encounters

Question 29

what happends when light encounters molecules in atmosphere ?

Answer 29

``` Shorter WL (blue) - more scattering Longer WL (red) - less scattering ``` this is called rayleigh scattering

Question 30

define rayleigh scattering?

Answer 30

when particle sizes are smaller than the wavelength of incident energy scattering by small particles

Question 31

define mie scattering?

Answer 31

particles and wavelengths around the same size larger particles >0.5 um eg smoke paricles/ very fine dust scattered equally though in a more forward direction atmosphere appears white

Question 32

define non-selective scattering

Answer 32

associated with large particles all wavelengths affected equally eg raindrops/cloud droplets/ice

Question 33

what wavelength is scatterred more? red or blue?

Answer 33

shorter blue wavelength scattered more than long red wavelength (alost 10 times more) scattering creates blue skies and red sunsets

Question 34

what 2 things absorbs solar output?

Answer 34

clouds gases and dust in atmosphere

Question 35

what makes up a hazy sunshine?

Answer 35

mie scattering - white around sun rayleigh scattering - blue sky away from sun

Question 36

what happens to the fraction of energy that makes it to the surface?

Answer 36

its radiated back to space (longwave radiation) if it wasnt radiated back to space then the earth would warm energy balance important but earth is warming now so energy isnt balanced

Question 37

how much insolation is lost back to space as shortwave radiation?

Answer 37

~31% reflected meaning ~69% absorbed

Question 38

what is the average planetary albedo?

Answer 38

~31% | this is high as moons albedo is 8%

Question 39

how much LW energy is radiated back to space?

Answer 39

~69%

Question 40

Name 3 ways insolation is remitted?

Answer 40

absorbed by ground and reemitted as longwave radiation emitted from ground directly to space emitted from ground and absorbed by atmosphere, then remmitted by atmosphere to space or the ground

Question 41

what regions radiate the most longwave radiation??

Answer 41

hot locations | they receive higher input of SW radiation

Question 42

describe 3 latitudinal variations in the energy balance?

Answer 42

more energy absorbed in tropics more reflection emitted in polar regions energy into earths surface balances energy out of earth ~36%

Question 43

what location receives the most energy?

Answer 43

tropics desert areas have less cloud so less scattering and lots of radiation reaches the surface over jungle theres clouds so more scattering and less radiation reaches the ground

Question 44

what location receives the least energy?

Answer 44

poles greater sun angle, greater distance through atmosphere, more scattering, greater seasonal variations insolation.