L2 EM Spectrum

Question 1

What is ‘Plancks Spectrum’?

Answer 1

All matter emits electromagnetic radiation when it has a temperature above absolute zero” [most things are assumed to be above this point so everything is emitting radiation

Question 2

What factor affects the wavelength of the radiation emitted?

Answer 2

Temperature

Question 3

What is Wien’s Law?

Answer 3

Peak wavelength = 3000/temperature

Question 4

What does Wien’s Law enable?

Answer 4

it allows us to define a relationship between temperature and wavelength

Question 5

What is wave theory?

Answer 5

Electromagnetic radiation consists of 2 component (magnetic and electric).

Question 6

What is electrical radiation component of wave theory?

Answer 6

varies in magnitude in a direction perpendicular to the direction in which radiation is travelling

Question 7

What is magnetic radiation component of wave theory?

Answer 7

Orientated at right angles to the electrical field.

Question 8

What speed do both the electrical and magnetic components of wave theory operate at?

Answer 8

Speed of light

Question 9

What is the wavelength, frequency and amplitude of a wave?

Answer 9

Wavelength = distance between peaks of two waves
Frequency = the number of waveforms passing through a point in time
Amplitude = the height of a waveform

Question 10

What equation derives from wave theory?

Answer 10

Speed of electromagnetic wave = frequency x wavelength

Question 11

What is the quantum theory equation?

Answer 11

energy of quantum = Plank Einstein relation (planck’s constant x frequency)

Question 12

What is wave-particle duality?

Answer 12

Combination of wave theory and wave-particle duality operated by Einstein

Question 13

What equation derived from wave-particle duality theory?

Answer 13

energy of quantum is inversely proportional to wavelength

Question 14

What are the implications for remote sensing of wave theory and all that?

Answer 14

The longer the wavelength of a subject, the less energy it emits and the harder it is for us to remotely sense. Therefore systems operating at long wavelengths must view larger images of the earth in order to obtain a detectable signal. Spatial and spectral resolution relationship.

Question 15

What are atmospheric windows?

Answer 15

They determine how much of the radiation being emitted by the earth or sun is re-emitted back or reaches the other side of the atmosphere.

Question 16

Why is it important to know about atmospheric windows?

Answer 16

Because it will then determine our decision regarding where to locate the remote sensing device (i.e. will enough energy be able to penetrate the atmosphere?)

Question 17

What is Rayleigh scattering?

Answer 17

Atmospheric particles scatter the radiation that it comes in to contact with.

Question 18

What is the relationship between wavelength and Rayleigh scattering?

Answer 18

Scatter increases with wavelength of radiation

Question 19

What is non-selective scattering?

Answer 19

Scattering caused by particles much larger in the atmosphere that scatter RGB light in equal amounts to each other thereby creating the appearance of white - that is why clouds are white

Question 20

What are the 2 forms of reflected radiation?

Answer 20

Specular - smooth surfaces cause almost all radiation to be redirected back towards the incident angle it arrived at
Diffusive - rough surfaces cause a random wild scattering of energy in all directions

Question 21

What is spectral reflectance?

Answer 21

The name given to the balancing of radiation that an object reflects, and absorbs, of different RGB visible wavelengths

Question 22

What defines what a colour is?

Answer 22

The balance of reflected radiation in the visible light of wavelengths

Question 23

What do satellites have that allows them to see the different wavelengths that are being reflected?

Answer 23

Bands

Question 24

What is Landsat 8’s band 8?

Answer 24

Panchromatic

Question 25

What is the panchromatic band?

Answer 25

A band that surveys a wider range of the EM spectrum that allows it to therefore take in more energy.

Question 26

What does the panchromatic band allow for in terms of spatial resolution?

Answer 26

Because the band lets in more light, it can decrease the spatial resolution and view things in more detail

Question 27

What can we do in ERDAS imagine that allows us to see what are normally non-visible wavelengths?

Answer 27

We can switch the wavelengths that appear in the computer’s primary colour bands (RGB).

Question 28

What can we determine by being able to view NIR?

Answer 28

Vegetation

Question 29

What is pan sharpening?

Answer 29

Using the Panchromatic band in Landsat 8 to enhance the satellite mage of the visible true colour image