PRESENTED BY

SUCHISMITA MUKHERJEE

TODAY’ S TOPIC

DEFINITION OF ELECTROMAGNETIC ENERGY CLASSIFICATION OF ENERGY INTERACTION ENERGY BALANCE RELATIONSHIP FACTORS CONTROLLING ENERGY INTERACTION WITH EARTH SURFACE FEATURES MATERIALS CONSTITUTING EARTH SURFACE WAVELENGTH OF ENERGY CONDITION OF FEATURES

a form of energy that is reflected or emitted from objects in the

form of electrical and magnetic waves that can travel through space.

can be detected only when it interacts with matters

There are many forms of electromagnetic energy including gamma

rays, x rays, ultraviolet radiation, visible light, infrared radiation,

microwaves and radio waves.

DEFINITION OF ELECTROMAGNETIC ENERGY

Electromagnetic energy is incident on any earth Surface feature

Three fundamental energy interactions with the feature are possible

Absorption (A) occurs when radiation (energy) is absorbed into the target

transmission (T) occurs when radiation passes through a target

Reflection (R) occurs when radiation "bounces" off the target and is redirected.

WATER SURFACE

REFLECTED ENERGY

INCIDENT ENERGY (EI)

ABSORBED

ENERGY TRANSMITTED ENERGY

BASIC INTERACTIONS BETWEEN ELECTROMAGNETIC ENERGY AND AN EARTH SURFACE FEATURE ( WATER BODY )

(ER)

(EA)(ET)

Proportion of the energy is

absorbed, transmitted or reflected by a material will depend upon

IN REMOTE SENSING, WE ARE

MOST INTERESTED IN

MEASURING THE RADIATION

REFLECTED FROM TARGETS.

Reflection from surfaces occurs in two

ways:

SPECULAR REFLECTORS

SPECULAR REFLECTORS

gives the mirror-like reflection of light (or of other kinds of wave) from a surface. in which light from a single incoming direction (a ray) is reflected into a single outgoing direction. the angle of incidence equals the angle of reflection (θi = θr in the figure),

Reflections on still water are an example of specular reflection

DIFFUSE REFLECTORS

DIFFUSE REFLECTORS

gives the reflection of light from a surface such that an incident ray is reflected at many angles rough surface does not give rise to images.

The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object. provides an illustrated method to show the types of electromagnetic radiation in terms of wavelength and frequency.

ELECTROMAGNETIC SPECTRUM

Here are the different types of radiation in the EM spectrum, in order from lowest energy to highest:

kind of energy that radio stations emit into the air. emitted by other things,such as stars and gases in space.

RADIO WAVE :

MICRO WAVE : in space are used by astronomers to learn about the

structure of nearby galaxies, and our own Milky Way cook your popcorn in just a few minutes!

INFRARED :Our skin emits infrared light, which is why we can be

seen in the dark by someone using night vision goggles IR light maps the dust between stars.

VESIBLE : this is the part that our eyes see emitted by everything from fireflies to light bulbs to stars

also by fast-moving particles hitting other particles.

ULTRA-VIOLET : Stars and other "hot" objects in space emit UV

radiation. cause our skin to burnX-RAY: Your doctor uses them to look at your bones and

your dentist to look at your teethGAMMA-RAY :

Radioactive materials (some natural and others made by man in things like nuclear power plants) can emit gamma-rays

Characterizes any given surface is dictated by the surface’s roughness in comparison to the wavelength of the energy incident upon it

Sandy beach

SPECTRAL REFLECTANCE (Rλ)

Rλ =ER(λ)EI(λ)

=Energy of wavelength reflected from the objectλ

Energy of wavelength incident upon the objectλx 100

reflected energy from earth surface is measured as function of wavelength

SPECTRAL REFLECTANCE

A graph of spectral reflectance of an object as a function of wavelengthClear water: Clear water has a low spectral reflectance (< 10%) in the visible regionAt wavelengths longer than 0.75 µm, water absorbs almost all the incoming energy Vegetation : generally has three reflectance valleys. one at the red spectral wavelength region (0.65 µm) is caused by high absorptance of energy by chlorophyll a and b in the leaves. other two at 1.45-1.55 µm and 1.90-1.95 µm are caused by high absorptance of energy by water in the leaves Dry soil : has a relatively flat reflectance curveWhen it is wet, its spectral reflectance drops due to water absorption

Body of the feature is HOTTER than its surroundings

Body of the feature is COOLER than its surroundings

emits more radiation Absorbs less radiation

tends to cool

emits less radiation Absorbs more radiation

tends to warm