This document summarizes the interaction between electromagnetic radiation and matter. It discusses how EMR is radiated from the sun and interacts with the atmosphere and Earth's surface. It interacts through absorption, scattering, reflection and transmission. The document outlines the different types of scattering that can occur in the atmosphere as well as atmospheric windows and absorption. It also discusses how EMR interacts with the Earth's surface through absorption, reflection and transmission and the different types of reflection. Finally, it provides examples of spectral reflectance properties of different materials like vegetation, soil and water.

1. Interaction between
Electromagnetic Radiation and
Matter
By:
Abdullah Khan
Center For Integrated Mountain Research Punjab
University

2. Electromagnetism
Electromagnetic Radiation
EMR__ Foundation Of Remote Sensing
EMR__ Interaction with Atmosphere
Atmospheric Windows
EMR__ Interaction with Earth Surface Features
Types of Reflection
Spectral Reflectance Properties
Contents

3.  It is the science of charge and of the forces and fields
associated with charge. Electricity and magnetism are
two aspects of electromagnetism.
 It is the phenomena associated with electric and
magnetic fields and their interactions with each other
and with electric charges and currents.
Electromagnetism

4. is radiated by atomic particles at the source (the Sun)
propagates through the vacuum of space at the speed
of light
interacts with the Earth's atmosphere
interacts with the Earth's surface
interacts with the Earth's atmosphere once again, and
finally reaches the remote sensors where it interacts
with various optical systems and detectors
Electromagnetic Radiation

6.  The foundation of remote sensing technology is based on the
measurement and interpretation of the patterns of EMR.
 necessary for remote sensing: energy source to illuminate the target
 consists of perpendicular fields travelling at the speed of light (c)
electrical field and magnetic field.
 The whole range of EMR is called spectrum.
 EMR is characterized by wavelength and frequency. Different
wavelengths or frequencies indicates different portion of EMR.
 EMR interact with atmosphere. The atmosphere causes significant
absorption and scattering of the wavelength.
 EMR also interact with the surface materials in the form of
absorption, reflection, and transmission.
EMR__Foundation of Remote Sensing Technology

8.  As the energy travels through the Earth’s atmosphere it is either:-
a) Scattered
b) Absorbed
 Scattering: causes EM radiation to be redirected from its original
path.
Rayleigh Scattering
Mie Scattering
Non-selective Scattering
 Absorption: molecules in the atmosphere absorb energy.
EMR__Interaction with the Atmosphere

10. Rayleigh Scattering
o interaction of particles smaller in diameter than the
wavelengths of the radiation.
o preferential scattering of shorter wavelengths (e.g.
ultraviolet and blue).
o caused by oxygen and nitrogen molecules in the upper
atmosphere.
EMR__ Interaction with the Atmosphere

11. Mie Scattering
 interaction of particles about the same diameter as the
wavelengths of the radiation.
 tends to affect longer wavelengths than Rayleigh
scatter.
 caused by water vapor and dust particles in the lower
atmosphere.
EMR__ Interaction with the Atmosphere

12. Non-Selective Scattering
 interaction of particles of larger diameter than the
wavelengths of the radiation
 scatters visible wavelengths equally
 caused by water droplets (in fog and clouds)
EMR__ Interaction with the Atmosphere

13.  Ozone:-absorbs ultraviolet radiation from the sun.
 Carbon dioxide:-absorbs in the far infrared portion of
the spectrum.
 Water vapor:-absorbs long wave infrared and shortwave
microwave radiations.
 atmospheric absorption has maximum affect on shorter
wavelengths (gamma, x-ray, UV)
 atmospheric absorption has little to no affect on
microwave radiation (longer wavelengths).
Atmospheric absorption

14. Atmospheric Windows
 those areas of the spectrum which are not severely
influenced by atmospheric absorption and thus, are
useful to remote sensors, are called atmospheric
windows.
 can pass through the atmosphere.
Atmospheric Blinds
 wavelengths which are blocked by the atmosphere.
EMR__Interaction with the Atmosphere

16.  three forms of interaction take place where energy is
incident upon the surface:
i. Absorption
ii. Transmission
iii. Reflection
 In remote sensing, are most interested in measuring the
radiation reflected from targets.
 The reflection of the energy depends on the degree of
surface roughness of the target relative to the
wavelength of the energy incident on it.
EMR__ Interaction with Earth’s Surface

17. Spectral Reflectance:
 the proportion of incident energy (I) of a given
wavelength interval that is reflected (R) by a particular
feature is referred to as the spectral reflectance (or
albedo) of that object.
Spectral Signature:
 the range of spectral reflectance of a particular feature at
different wavelengths is called the spectral signature (or
spectral reflectance curve) of the object.
EMR__Interaction with Earth Surface Features

18.  We refer to two types of reflection, which represent the two extreme
ends of the way in which energy is reflected from a target: specular
reflection and diffuse reflection.
 Whether a particular target reflects specularly or diffusely, or
somewhere in between, depends on the surface roughness of the
feature in comparison to the wavelength of the incoming radiation.
 If the wavelengths are much smaller than the surface variations or
the particle sizes that make up the surface, diffuse reflection will
dominate.
 For example, fine-grained sand would appear fairly smooth to long
wavelength microwaves but would appear quite rough to the visible
wavelengths.
Types of Reflection

19.  Reflection off of smooth surfaces such as mirrors or a
calm body of water leads to a type of reflection known
as specular reflection.
Spectral reflectance

20.  Reflection off of rough surfaces such as clothing, paper,
and the asphalt roadway leads to a type of reflection
known as diffuse reflection.
Diffused reflectance

21.  How much of EMR will be reflected depends on the nature of the
materials and which portion of the EMR is being measured.
 The nature of this reflected component over a range of wavelengths is
called spectral response patterns.
 Spectral patterns are descriptions of the degree to which energy is
reflected in different regions of the spectrum. Spectral Signature
 Every natural and artificial object reflects and emits EMR over a range
of wavelengths in its own chemical composition and physical state.
 Within some limited wavelength region, a particular object will usually
exhibit a diagnostic spectral response patterns that differs from other
objects.
Spectral Reflectance Properties

22.  beyond 1.3 μm energy incident upon vegetation is
essentially absorbed or reflected with little to no
transmittance of energy
 dips in reflectance occur at 1.4, 1.9 and 2.7 μm because
water in the leaf absorbs strongly at these wavelengths
 reflectance peaks occur at about 1.6 μm and 2.2 μm,
between the absorption bands
Spectral reflectance of Vegetation

23. • the factors that influence soil reflectance act over less
specified spectral bands
• factors affecting soil reflectance are moisture content,
soil texture (proportion of sand, silt and clay), surface
roughness, presence of iron oxide and organic matter
content
• the presence of moisture in soil will decrease its
reflectance
 absorption bands at about 1.4, 1.9, 2.2 and 2.7 μm
Spectral reflectance of Soil

24.  Water absorbs radiation at near-IR wavelengths and
beyond (strong absorption bands at about 1.4, 1.9 and
2.7 μm)
 Clear water absorbs relatively little energy with
wavelengths < 0.6 μm, resulting in high transmittance in
the blue-green portion of the spectrum •
 • Increases in chlorophyll concentration tend to decrease
reflectance in blue wavelengths and increase it in green
wavelengths.
Spectral reflectance of Water

26.  www.wikipedia.com
 support.esri.com
 www.oceanoptics.com
 www.colorado.edu
 oregonstate.edu
 www.ntd-ed.org
 resources.yesican-science
References