Skip to main content

EMR Spectrum Remote Sensing

The Electromagnetic Radiation (EMR) Spectrum is like a set of invisible waves that carry energy. In remote sensing, satellites and sensors use these waves to collect information about the Earth—like forests, water, cities, clouds, temperature, and more.

Just like how our eyes can only see visible light (like colors in a rainbow), sensors in remote sensing can "see" many more types of waves that humans can't.

 Types of EMR Used in Remote Sensing:

Type of WaveWavelengthWhat It's Used ForExample
Visible Light0.4 – 0.7 micrometersTo take normal satellite imagesGoogle Earth pictures
Near-Infrared0.7 – 1.0 µmTo check plant healthGreen areas, farming
Shortwave Infrared (SWIR)1.0 – 3.0 µmTo see moisture in soil and vegetationDrought or wetness studies
Thermal Infrared (TIR)8.0 – 14.0 µmTo measure surface temperatureHeat from buildings, forest fires
Microwaves1 mm – 1 meterTo see through clouds and at night (radar)Flood detection, weather, disasters

 How Does It Work?

  • The Sun sends out energy waves.

  • These waves hit the Earth and reflect back.

  • Satellites or sensors in space or airplanes catch these waves.

  • Scientists study these waves to understand what is on the Earth—like whether an area has trees, water, buildings, or is too hot or cold.

What We See vs. What Sensors See

  • Our eyes can only see visible light.

  • But remote sensing sensors can "see" infrared, thermal, and microwaves—this helps us see things that are invisible to the human eye!

 Key Points to Remember

✅ EMR spectrum has different types of waves—some short, some long.
✅ Each type of wave gives different information about the Earth.
✅ Remote sensing uses these waves to study our planet safely from space.
✅ It helps in weather prediction, disaster monitoring, farming, forest health, and city planning.

Comments

Popular posts from this blog

Natural Disasters

A natural disaster is a catastrophic event caused by natural processes of the Earth that results in significant loss of life, property, and environmental resources. It occurs when a hazard (potentially damaging physical event) interacts with a vulnerable population and leads to disruption of normal life . Key terms: Hazard → A potential natural event (e.g., cyclone, earthquake). Disaster → When the hazard causes widespread damage due to vulnerability. Risk → Probability of harmful consequences from interaction of hazard and vulnerability. Vulnerability → Degree to which a community or system is exposed and unable to cope with the hazard. Resilience → Ability of a system or society to recover from the disaster impact. 👉 Example: An earthquake in an uninhabited desert is a hazard , but not a disaster unless people or infrastructure are affected. Types Natural disasters can be classified into geophysical, hydrological, meteorological, clim...

Types of Remote Sensing

Remote Sensing means collecting information about the Earth's surface without touching it , usually using satellites, aircraft, or drones . There are different types of remote sensing based on the energy source and the wavelength region used. 🛰️ 1. Active Remote Sensing 📘 Concept: In active remote sensing , the sensor sends out its own energy (like a signal or pulse) to the Earth's surface. The sensor then records the reflected or backscattered energy that comes back from the surface. ⚙️ Key Terminology: Transmitter: sends energy (like a radar pulse or laser beam). Receiver: detects the energy that bounces back. Backscatter: energy that is reflected back to the sensor. 📊 Examples of Active Sensors: RADAR (Radio Detection and Ranging): Uses microwave signals to detect surface roughness, soil moisture, or ocean waves. LiDAR (Light Detection and Ranging): Uses laser light (near-infrared) to measure elevation, vegetation...

geostationary and sun-synchronous

Orbital characteristics of Remote sensing satellite geostationary and sun-synchronous  Orbits in Remote Sensing Orbit = the path a satellite follows around the Earth. The orbit determines what part of Earth the satellite can see , how often it revisits , and what applications it is good for . Remote sensing satellites mainly use two standard orbits : Geostationary Orbit (GEO) Sun-Synchronous Orbit (SSO)  Geostationary Satellites (GEO) Characteristics Altitude : ~35,786 km above the equator. Period : 24 hours → same as Earth's rotation. Orbit type : Circular, directly above the equator . Appears "stationary" over one fixed point on Earth. Concepts & Terminologies Geosynchronous = orbit period matches Earth's rotation (24h). Geostationary = special type of geosynchronous orbit directly above equator → looks fixed. Continuous coverage : Can monitor the same area all the time. Applications Weather...

Linear Arrays Along-Track Scanners or Pushbroom Scanners

Multispectral Imaging Using Linear Arrays (Along-Track Scanners or Pushbroom Scanners) Multispectral Imaging: As previously defined, this involves capturing images using multiple sensors that are sensitive to different wavelengths of electromagnetic radiation. Linear Array of Detectors (A): This refers to a row of discrete detectors arranged in a straight line. Each detector is responsible for measuring the radiation within a specific wavelength band. Focal Plane (B): This is the plane where the image is formed by the lens system. It is the location where the detectors are placed to capture the focused image. Formed by Lens Systems (C): The lens system is responsible for collecting and focusing the incoming radiation onto the focal plane. It acts like a camera lens, creating a sharp image of the scene. Ground Resolution Cell (D): As previously defined, this is the smallest area on the ground that can be resolved by a remote sensing sensor. In the case of linear array scanne...

India remote sensing

1. Foundational Phase (Early 1970s – Early 1980s) Objective: To explore the potential of space-based observation for national development. 1972: The Space Applications Programme (SAP) was initiated by the Indian Space Research Organisation (ISRO), focusing on applying space technology for societal benefits. 1975: The Department of Space (DoS) was established, providing an institutional base for space applications, including remote sensing. 1977: India began aerial and balloon-borne experiments to study Earth resources and assess how remote sensing data could aid in agriculture, forestry, and hydrology. 1978 (June 7): Bhaskara-I launched by the Soviet Union — India's first experimental Earth Observation satellite . Payloads: TV cameras (for land and ocean surface observation) and a Microwave Radiometer. Significance: Proved that satellite-based Earth observation was feasible for India's needs. 1981 (November 20): Bhaskara-II launche...